Economically Useful Plants And Entrepreneurial Botany

Class 12 | Biology — Botany | Chapter 10

Class 12 Unit 10 Biology

Learning Objectives

The learner will be able to:

• Acquire knowledge about origin, area of cultivation and uses of various food yielding plants.
• Describe the different spices and condiments and their uses.
• Elicit the uses of fibre, timbers, paper and dye yielding plants.
• Acquire knowledge about the active principles, chemical composition and medicinal uses of plants.
• Gain knowledge of organic farming – bio fertilisers and bio pest repellants.

Chapter Outline

• 10.1 Food Plants
• 10.2 Spices and Condiments
• 10.3 Fibre
• 10.4 Timber
• 10.5 Latex
• 10.6 Pulp wood
• 10.7 Dye
• 10.8 Cosmetics
• 10.9 Traditional system of medicines
• 10.10 Medicinal plants
• 10.11 Entrepreneurial Botany

The land and water of the earth sustain a vast assemblage of plants upon which all other living forms are directly or indirectly dependent. Pre-historic humans lived on berries, tubers, herbage, and the wild game which they collected and hunted that occupied whole of their time. Domestication of plants and animals has led to the production of surplus food which formed the basis for civilizations. Early civilization in different parts of the world has domesticated different species of plants for various purposes. Based on their utility, the economically useful plants are classified into food plants, fodder plants, fibre plants, timber plants, medicinal plants, and plants used in paper industries, dyes and cosmetics. Selected examples of economically important plants for each category are discussed in this chapter.

10.1 Food Plants

Currently about 10,000 food plants are being used of which only around 1,500 species were brought under cultivation. However, food base of majority of the population depends only on three grass species namely rice, wheat and maize.

10.1.1 Cereals

The word cereal is derived from Ceres, which according to the Roman mythology denotes "Goddess of agriculture". All cereals are members of grass family (Poaceae) that are grown for their edible starchy seeds. The prominence of cereals as food plants is due to the following attributes:

1. Greater adaptability and successful colonisation on every type of habitat.
2. The relative ease of cultivation.
3. Tillering property that produce more branches which results in higher yield per unit area.
4. Compact and dry grains that they can be easily handled, transported and stored without undergoing spoilage.
5. High caloric value that provides energy.

The nutrients provided by cereals include carbohydrates, proteins, fibres and a wide range of vitamins and minerals. Cereals can be classified into two different types based on their size namely Major Cereals and Minor Cereals.

Major Cereals

Rice or Paddy

Botanical name: Oryza sativa

Paddy is a semi-aquatic crop and is grown in standing water. It is an important food crop of the world, occupying the second position in terms of area under cultivation and production, next to wheat. Rice is the chief source of carbohydrate.

Origin and Area of cultivation: South East Asia is considered as the center of origin of rice. Earliest evidences of rice cultivation have been found in China, India and Thailand. It is mainly cultivated in Delta and irrigated regions of Tamil Nadu.

Uses:

• Rice is the easily digestible calorie rich cereal food which is used as a staple food in Southern and North East India.
• Various rice products such as Flaked rice (Aval), Puffed rice/parched rice (Pori) are used as breakfast cereal or as snack food in different parts of India.
• Rice bran oil obtained from the rice bran is used in culinary and industrial purposes.
• Husks are used as fuel, and in the manufacture of packing material and fertilizer.

Wheat

Botanical name: Triticum aestivum

Origin and Area of cultivation: Earliest evidence for wheat cultivation comes from Fertile Crescent region. The common cultivated wheat, Triticum aestivum is cultivated for about 7,500 years. Wheat is mostly cultivated in the North Indian states such as Uttar Pradesh, Punjab, Haryana, Rajasthan, Madhya Pradesh and Bihar.

Uses:

• Wheat is the staple food in Northern India.
• Wheat flour is suitable to make bread and other bakery products.
• Processed wheat flour, that has little fibre, is called Maida which is used extensively in making parota, naan and bakery products.
• Malted wheat is a major raw material for producing alcoholic beverages and nutritive drinks.

Do You Know?

Pseudo Cereal – Chenopodium quinoa

The term pseudo-cereal is used to describe foods that are prepared and eaten as a whole grain, but are botanical outliers from grasses. Example: quinoa. It is actually a seed from the Chenopodium quinoa plant which belongs to the family Amaranthaceae. It is a gluten-free, whole-grain carbohydrate, as well as a whole protein (meaning it contains all nine essential amino acids) and have been eaten for 6000 years in Andes hill region.

Maize – Uses

• Most of the corn produced is used as fodder than food.
• Corn syrup is used in the manufacture of infant foods.
• Corn is a raw material in the industrial production of alcohol and alcoholic beverages.

10.1.2 Millets (Siru Thaniyangal)

The term millet is applied to a variety of very small seeds originally cultivated by ancient people in Africa and Asia. They are gluten free and have less glycemic index.

Finger Millet – Ragi

Botanical name: Eleusine coracana

Finger millet is the crop of early introduction from East Africa into India. Ragi is rich in calcium.

Uses:

• It is used as a staple food in many southern hilly regions of India.
• Ragi grains are made into porridge and gruel.
• Ragi malt is the popular nutrient drink.
• It is used as a source of fermented beverages.

Sorghum

Botanical name: Sorghum vulgare

Sorghum is native to Africa. It is one of the major millets in the world and is rich in calcium and iron.

Uses:

• It is fed to poultry, birds, pigs and cattle.
• It is a source of fermented alcoholic beverage.

10.1.3 Minor Millets

Foxtail Millet

Botanical name: Setaria italica

This is one of the oldest millet used traditionally in India, which is domesticated first in China about 6000 years ago. Rich in protein, carbohydrate, vitamin B and C, Potassium and Calcium.

Uses:

• It supports in strengthening of heart and improves eye sight.
• Thinai porridge is given to lactating mother.

Kodo Millet

Botanical name: Paspalum scrobiculatum

Kodo millet is originated from West Africa, which is rich in fibre, protein and minerals.

Uses:

• Kodo millet is ground into flour and used to make pudding.
• Good diuretic and cures constipation.
• Helps to reduce obesity, blood sugar and blood pressure.

10.1.4 Pulses

The word Pulse is derived from the Latin words 'puls' or 'pultis' meaning "thick soup". Pulses are the edible seeds that are harvested from the fruits of Fabaceae. They provide vital source of plant-based protein, vitamins and minerals for people around the globe.

Black Gram

Botanical name: Vigna mungo

Origin and Area of cultivation: Black gram is native to India. Earliest archeobotanical evidences record the presence of black gram about 3,500 years ago. It is cultivated as a rain fed crop in drier parts of India. India contributes to 80% of the global production of black gram. Important states growing black gram in India are Uttar Pradesh, Chattisgarh and Karnataka.

Uses:

• Black gram is eaten whole or split, boiled or roasted or ground into flour.
• Black gram batter is a major ingredient for the preparation of popular Southern Indian breakfast dishes.
• Split pulse is used in seasoning Indian curries.

Red Gram / Pigeon Pea

Botanical name: Cajanus cajan

Origin and Area of cultivation: It is the only pulse native to Southern India. It is mainly grown in the states of Maharashtra, Andhra Pradesh, Madhya Pradesh, Karnataka and Gujarat.

Uses:

• Red gram is a major ingredient of sambar, a characteristic dish of Southern India.
• Roasted seeds are consumed either salted or unsalted as a popular snack.
• Young pods are cooked and consumed.

Green Gram

Botanical name: Vigna radiata

Origin and Area of cultivation: Green gram is a native of India and the earliest archaeological evidences are found in the state of Maharashtra. It is cultivated in the states of Madhya Pradesh, Karnataka and Tamil Nadu.

Uses:

• It can be used as roasted, cooked and sprouted pulse.
• Green gram is one of the ingredients of pongal, a popular breakfast dish in Tamil Nadu.
• Fried dehulled and broken or whole green gram is used as popular snack.
• The flour is traditionally used as a cosmetic, especially for the skin.

10.1.5 Vegetables

While walking through a market filled with fresh vegetables like stacks of lady's finger, mountains of potatoes, pyramids of brinjal, tomatoes, cucurbits, we learn to choose the vegetables that is fresh, tender, ripe and those suit the family taste through experience and cultural practices. Vegetables are the important part of healthy eating and provide many nutrients, including potassium, fiber, folic acid and vitamins A, E and C. The nutrients in vegetables are vital for maintenance of our health.

Lady's Finger / Okra

Botanical name: Abelmoschus esculentus

Family: Malvaceae

Origin and Area of cultivation: Lady's finger is a native of the Tropical Africa. Assam, Maharashtra and Gujarat are the important states where Lady's finger is grown in abundance. Coimbatore, Dharmapuri and Vellore are the major cultivating regions of Tamil Nadu.

Uses:

• The fresh and green tender fruits are used as a vegetable.
• Often they are sliced and dehydrated to conserve them for later use.
• It has most important nutrients.

10.1.6 Fruits

Edible fruits are fleshy structures with a pleasant aroma and flavours. Fruits are sources of many nutrients including potassium, dietary fiber, folic acid and vitamins. Depending on the climatic region in which fruit crops grow, they can be classified into temperate (apple, pear, plum) and tropical fruits (mango, jack, banana).

Mango (National fruit of India)

Botanical name: Mangifera indica

Family: Anacardiaceae

Origin and Area of cultivation: The mango is the native to Southern Asia, especially Burma and Eastern India. It is the National fruit of India. Major mango producing States are Andhra Pradesh, Bihar, Gujarat and Karnataka. Salem, Krishnagiri, Dharmapuri are the major mango producing districts of Tamil Nadu. Some of the major cultivars of mango in India are Alphonsa, Banganapalli, Neelam and Malgova.

Uses:

• Mango is the major table fruit of India, which is rich in beta carotenes.
• It is utilized in many ways, as dessert, canned, dried and preserves in Indian cuisine.
• Sour, unripe mangoes are used in chutneys, pickles, side dishes, or may be eaten raw with salt and chili.
• Mango pulp is made into jelly.
• Aerated and non-aerated fruit juice is a popular soft drink.

10.1.7 Nuts

Nuts are simple dry fruits composed of a hard shell and an edible kernel. They are packed with a good source of healthy fats, fibre, protein, vitamins, minerals and antioxidants.

Cashew Nut

Botanical name: Anacardium occidentale

Family: Anacardiaceae

Origin and Area of cultivation: Cashew has originated in Brazil and made its way to India in the 16th century through Portuguese sailors. Cashew is grown in Kerala, Karnataka, Goa, Maharashtra, Tamil Nadu, and Orissa.

Uses:

• Cashews are commonly used for garnishing sweets or curries, or ground into a paste that forms a base of sauces for curries or some sweets.
• Roasted and raw kernels are used as snacks.

10.1.8 Sugars

We experienced sweetness while eating the stems of sugarcane, roots of sugar beet, fruits of apple and while drinking palmyra sap. This is due to the different proportions of sugars found in it. Sugar is the generic name for sweet tasting soluble carbohydrate, which are used in foods and beverages. Sugars found in sugarcane and palmyra make them ideal for efficient extraction to make commercial sugar.

Sugarcane

Botanical name: Saccharum officinarum

Family: Poaceae

Origin and Area of cultivation: The cultivated Saccharum officinarum has evolved by repeated back crossing of S. officinarum of New Guinea with wild S. spontaneum of India to improve the quality. All districts except Kanyakumari and Nilgiris of Tamil Nadu cultivate Sugarcane.

Uses:

• Sugar cane is the raw material for extracting white sugar.
• Sugarcane supports large number of industries like sugar mills producing refined sugars, distilleries producing liquor grade ethanol and millions of jaggery manufacturing units.
• Fresh sugarcane juice is a refreshing drink.
• Molasses is the raw material for the production of ethyl alcohol.

Palmyra (State tree of Tamil Nadu)

Botanical name: Borassus flabellifer

Family: Arecaceae

Origin and Area of cultivation: Palmyra is native to tropical regions of Africa, Asia and New Guinea. Palmyra grows all over Tamil Nadu, especially in coastal districts.

Uses:

• Exudate from inflorescence axis is collected for preparing palm sugar.
• Inflorescence is tapped for its sap which is used as health drink.
• Sap is processed to get palm jaggery or fermented to give toddy.
• Endosperm is used as a refreshing summer food.
• Germinated seeds have an elongated embryo surrounded by fleshy scale leaf which is edible.

10.1.9 Oil Seeds

There are two kinds of oils namely, essential oils and vegetable oils or fatty oils. The essential oils or volatile oils which possess aroma evaporate or volatilize in contact with air. Any organ of a plant may be the source of essential oil. For example, flowers of Jasmine, fruits of orange and roots of ginger. The vegetable oils or non-volatile oils or fixed oils do not evaporate. Whole seeds or endosperm form the sources of vegetable oils.

Groundnut / Peanut

Botanical name: Arachis hypogaea

Family: Fabaceae

Origin and Area of Cultivation: Groundnut is native of Brazil. Portuguese introduced groundnut into Africa. The Spanish took it to the South East Asia and India via Philippines. In India Gujarat, Andhra Pradesh and Rajasthan are top producers.

Uses:

• Nuts contain about 45% oil. The kernels are also rich sources of phosphorous and vitamins, particularly thiamine, riboflavin and niacin.
• It is premium cooking oil because it does not smoke.
• Lower grade oil is used in manufacture of soaps and lubricants.

Sesame / Gingelly

Botanical name: Sesamum indicum

Family: Pedaliaceae

Origin and Area of cultivation: Sesamum indicum has originated from Africa. Sesame is cultivated as a dry land crop. West Bengal and Madhya Pradesh are the top producers in India during 2017-18. It is considered as a healthy oil in Southern Indian culture.

Uses:

• Sesame oil is used for mostly culinary purposes in India.
• Lower grades are used in manufacture of soaps, in paint industries, as a lubricant and as an illuminant.
• In India, the oil is the basis of most of the scented oils used in perfumes.
• Sesame seed snacks are popular throughout India.

10.1.10 Beverages

All non-alcoholic beverages contain alkaloids that stimulate central nervous system and also possess mild diuretic properties.

Coffee

Botanical name: Coffea arabica

Family: Rubiaceae

Origin and Area of cultivation: Coffea arabica is the prime source of commercial coffee which is native to the tropical Ethiopia. An Indian Muslim saint, Baba Budan introduced coffee from Yemen to Mysore. Karnataka is the largest coffee producing state in India followed by Tamil Nadu and Kerala. Tamil Nadu is the largest consumer of coffee in India.

Uses: Drinking coffee in moderation provides the following health benefits:

• Caffeine enhances release of acetylcholine in brain, which in turn enhances efficiency.
• It can lower the incidence of fatty liver diseases, cirrhosis and cancer.
• It may reduce the risk of type 2 diabetes.

10.2 Spices and Condiments

"Aroma attracts everyone"

History: Spices were used extensively throughout the world for several thousands of years. Records of use of garlic and onion dates back 2500 years. Majority of the spices are native to Mediterranean region, India and South East Asian countries. Spices, especially pepper triggered the search for sea route to India and paved way for the exploratory voyages by Spanish and Portuguese.

Spices are accessory foods mainly used for flavouring during food preparation to improve their palatability. Spices are aromatic plant products and are characterized by sweet or bitter taste. Spices are added in minimal quantities during the cooking process. For example, black pepper.

Condiments, on the other hand, are flavouring substances having a sharp taste and are usually added to food after cooking. For example, curry leaves.

Cardamom

Botanical name: Elettaria cardamomum

Family: Zingiberaceae

Origin and Area of cultivation: It is indigenous to Southern India and Sri Lanka. Cardamom is called as "Queen of Spices". In India it is one of the main cash crops cultivated in the Western Ghats, and North Eastern India.

Uses:

• The seeds have a pleasing aroma and a characteristic warm, slightly pungent taste.
• It is used for flavouring confectionaries, bakery products and beverages.
• The seeds are used in the preparation of curry powder, pickles and cakes.
• Medicinally, it is employed as a stimulant and carminative.
• It is also chewed as a mouth freshener.

Black Pepper

Botanical name: Piper nigrum

Family: Piperaceae

Origin and Area of cultivation: It is indigenous to Western Ghats of India. Pepper is one of the most important Indian spices referred to as the "King of Spices" and also termed as "Black Gold of India". Kerala, Karnataka and Tamil Nadu are the top producers in India. The characteristic pungency of the pepper is due to the presence of alkaloid Piperine. There are two types of pepper available in the market namely black and white pepper.

Uses:

• It is used for flavouring in the preparation of sauces, soups, curry powder and pickles.
• It is used in medicine as an aromatic stimulant for enhancing salivary and gastric secretions and also as a stomachic.
• Pepper also enhances the bio-absorption of medicines.

Turmeric

Botanical name: Curcuma longa

Family: Zingiberaceae

Origin and Area of cultivation: It is indigenous to Southern Asia. India is the largest producer, consumer and exporter of turmeric. Erode in Tamil Nadu is the World's largest wholesale turmeric market.

Uses:

• Turmeric is one of the most important and ancient Indian spices and used traditionally over thousands of years for culinary, cosmetic, dyeing and for medicinal purposes.
• It is an important constituent of curry powders.
• Turmeric is used as a colouring agent in pharmacy, confectionery and food industry.
• Rice coloured with turmeric (yellow) is considered sacred and auspicious which is used in ceremonies.
• It is also used for dyeing leather, fibre, paper and toys.
• Curcumin extracted from turmeric is responsible for the yellow colour.
• Curcumin is a very good anti-oxidant which may help fight various kinds of cancer.
• It has anti-inflammatory, anti-diabetic, anti-bacterial, anti-fungal and antiviral activities.
• It stops platelets from clotting in arteries, which leads to heart attack.

Chillies or Red Pepper

Botanical name: Capsicum annuum, C. frutescens

Family: Solanaceae

Origin and Area of cultivation: Capsicum is native to South America and is popularly known as chillies or red pepper in English. India is leading producer and exporter. C. annuum and C. frutescens are important cultivated species of chillies.

Uses:

• The fruits of C. annuum are less pungent than the fruits of C. frutescens. C. annuum includes large, sweet bell peppers.
• Long fruit cultivars of this species are commercially known as 'Cayenne pepper' which are crushed, powdered and used as condiment.
• Chillies are used in manufacture of sauces, curry powders and preparation of pickles.
• Capsaicin is an active component of chillies. It has pain relieving properties and used in pain relieving balms.
• Chillies are a good source of Vitamin C, A and E.

Do You Know?

Capsaicin is responsible for the pungency or spicy taste of chillies. Pungency of Chillies is measured in Scoville Heat Units (SHU). World's hottest chilli, Carolina reaper pepper measures 2200000 SHU. Naga viper chilli is the hottest in India that measures 1349000 SHU. Commonly used cayenne pepper measures 30000 to 50000 SHU.

Condiment – Tamarind

Botanical name: Tamarindus indica

Family: Fabaceae – Caesalpinioideae

Origin and Area of cultivation: Tamarind is native of tropical African region and was introduced into India several thousand years before. It is cultivated in India, Myanmar, south Asian countries and several African and Central American countries. Tamarind has long been used in Africa and in Southern Asia. The name tamarindus is of Arabian origin, which means "dates of India" (tamar – dates; Indus – India).

Uses:

• It is used in flavouring sauces in the United States and Mexico.
• In India, the fruit pulp is major ingredient for many culinary preparations.
• Sweet tamarinds are sold as table fruits in India imported from Thailand and Malaysia.

10.3 Fibres

Botanically a fiber is a long narrow and thick walled cell.

Cotton

Botanical name: Gossypium spp.

Family: Malvaceae

Cotton is the world's most important nonfood commercial crop.

Origin and Area of cultivation: It is one of the oldest cultivated crops of the world. It has been cultivated for about 8000 years both in new world and in old world. Commercial cotton comes from four cotton species: two from the new world and two from the old world. (1) G. hirsutum (2) G. barbadense are the New world species and (3) G. arboretum (4) G. herbaceum are the old world species. In India cotton is cultivated in Gujarat, Maharashtra, Andhra Pradesh and Tamil Nadu.

Uses: It is mainly used in the manufacturing of various textile, hosiery products, toys and is also used in hospitals.

Jute

Botanical name: Corchorus species

Family: Malvaceae

Origin and Area of cultivation: Jute is derived from the two cultivated species (1) Corchorus capsularis and (2) C. olitorius is of African origin whereas C. capsularis is believed to be Indo-Burmese origin. It is an important cultivated commercial crop in Gangetic plains of India and Bangladesh.

Uses:

• It is one of the largest exported fibre material of India.
• The jute industry occupies an important place in the national economy of India.
• Jute is used for 'safe' packaging in view of being natural, renewable, bio-degradable and eco-friendly product.
• It is used in bagging and wrapping textile.
• About 75% of the jute produced is used for manufacturing sacks and bags.
• It is also used in manufacture of blankets, rags, curtains etc.
• It is also being used as a textile fibre in recent years.

10.4 Timber

The basic need of shelter is obtained from the timber trees.

Teak

Botanical name: Tectona grandis

Family: Lamiaceae

Origin and Area of cultivation: This is native to South east Asia. It is observed wild in Assam. But cultivated in Bengal, Assam, Kerala, Tamil Nadu and North-West India.

Uses:

• It is one of best timbers of the world.
• The heartwood is golden yellow to golden brown when freshly sawn, turning darker when exposed to light.
• Known for its durability as it is immune to the attack of termites and fungi.
• The wood does not split or crack and is a carpenter friendly wood.
• It was the chief railway carriage and wagon wood in India.
• Ship building and bridge-building depends on teakwood.
• It is also used in making boats, toys, plywood, door frames and doors.

10.5 Latex

Rubber

Botanical name: Hevea brasiliensis

Family: Euphorbiaceae

Origin and Area of cultivation: It is a native of Brazil and was introduced outside its native range during the colonial period and has become an important cash crop. Asia contributed 90% of the world production. Kerala is the largest producer in India followed by Tamil Nadu.

Uses:

• Tyre and other automobile parts manufacturing industries consume 70% of the rubber production.
• Rubber is used in manufacturing footwear, wire and cable insulations, raincoats, household and hospital goods, shock absorbers, belts, sports goods, erasers, adhesives, and rubber-bands.
• Hard rubber is used in the electrical and radio engineering industries.
• Concentrated latex is used for making gloves, balloons and condoms.
• Foamed latex is used in the manufacture of cushions, pillows and lifebelts.

Do You Know?

Rubber – Vulcanization: Charles Goodyear invented vulcanization in 1839. He found that the defects in rubber articles could be overcome by heating rubber with sulphur under pressure at 150°C. The process was called vulcanization. The name was given from the Roman God of Fire, Vulcan. Because of this, solid rubber tyres were used for first time in 1867.

10.6 Pulp Wood

The term paper is derived from the word 'papyrus' a plant (Cyperus papyrus) that was used by Egyptians to make paper-like materials. Paper production is a Chinese invention. The Chinese discovered the paper that was prepared from the inner bark of paper mulberry in 105 A.D. For a long time, the art of paper making remained a monopoly of the Chinese until Arabs learned the technique and improved it around 750 A.D. Invention of printing increased the demand for paper.

Manufacture of Wood pulp: Wood is converted into pulp by mechanical, and chemical processes. Wood of Melia azadirachta, Neolamarkia chinensis, Casuarina spp., Eucalyptus spp. are used for making paper pulp.

Do You Know?

Purified dissolving pulp is used as a basic material in the manufacture of rayon or artificial silk, fabrics, transparent films (cellophane, cellulose acetate films), plastics. The viscose process of making rayon is the most common process.

10.7 Dyes

The ability to perceive colour is a wonderful aspect of human eyes and dyes add colour to the goods we use. They have been in use since the ancient times. The earliest authentic records of dyeing were found in the tomb painting of ancient Egypt. Colourings on mummy cements (wrapping) included saffron and indigo. They can also be seen in rock paintings in India.

Henna

Botanical name: Lawsonia inermis

Family: Lythraceae

Origin and Area of cultivation: It is indigenous to North Africa and South-west Asia. It is grown mostly throughout India, especially in Gujarat, Madhya Pradesh and Rajasthan.

Uses:

• An orange dye 'Henna' is obtained from the leaves and young shoots of Lawsonia inermis.
• The principal colouring matter of leaves 'lacosone' is harmless and causes no irritation to the skin.
• This dye has long been used to dye skin, hair and finger nails.
• It is used for colouring leather, for the tails of horses and in hair-dyes.

10.8 Cosmetics

Traditionally in Southern India, people have been using turmeric, green gram powder, henna, sigaikai and usilai for their skin and hair care. These were mostly home prepared products that are used for grooming. Today, cosmetics have a high commercial value and have become chemical based industrial products. Providing personal care services has become a major industry. In recent years, people have realized the hazards of chemical-based cosmetics and are turning back to natural products.

Aloe

Botanical name: Aloe vera

Family: Asphodelaceae (formerly Liliaceae)

Origin and Area of cultivation: It is a native of Sudan. It is cultivated on a large scale in Rajasthan, Gujarat, Maharashtra, Andhra Pradesh and Tamil Nadu.

Uses:

• 'Aloin' (a mixture of glucosides) and its gel are used as skin tonic.
• It has a cooling effect and moisturizing characteristics and hence used in preparation of creams, lotions, shampoos, shaving creams, after shave lotions and allied products.
• It is used in gerontological applications for rejuvenation of aging skin.
• Products prepared from aloe leaves have multiple properties such as emollient, antibacterial, antioxidant, antifungal and antiseptic.
• Aloe vera gel is used in skin care cosmetics.

10.8.1 Perfumes

The word perfume is derived from the Latin word Per (through) and fumus (to smoke), meaning through smoke. It refers to the age-old tradition of burning scented woods at religious ceremonies. In early days, when people were less conscious of personal hygiene, essential oils not only masked offensive odours, but also may have acted as antiseptics. Perfumes are added to baths and used for anointing the body. Perfumes are manufactured from essential oil which are volatile and aromatic. Essential oils are found at different parts of the plant such as leaves (curry leaf, mint), flowers (rose, jasmine), fruits (citrus, strawberry) and wood (sandal, eucalyptus).

Madurai Malli

'Madurai Malli' is the pride of Madurai and has a distinct reputation universally because of its uniqueness and has been given the Geographical Indications (GI) mark by the Geographical indication Registry of India. Madurai Malli has thick petals with long stalk equal to that of petals and the distinct fragrance is due to the presence of chemicals such as jasmine and alpha terpineol. This makes it easy to distinguish Madurai Malli from other places. This is the second GI tag for Jasmine after 'Mysore Malli'.

Jasmine

Botanical name: Jasminum grandiflorum

Family: Oleaceae

Jasmine, as a floral perfume, ranks next to the rose oil. Major species cultivated on the commercial scale is Jasminum grandiflorum, a native of the north-western Himalayas. In Tamil Nadu, the major jasmine cultivation centres are Madurai and Thovalai of Kanyakumari District. The essential oil is present in the epidermal cells of the inner and outer surfaces of both the sepals and petals. One ton of Jasmine blossom yields about 2.5 to 3 kg of essential oil, comprising 0.25 to 3% of the weight of the fresh flower.

Uses:

• Jasmine flowers have been used since ancient times in India for worship, ceremonial purposes, incense and fumigants, as well as for making perfumed hair oils, cosmetics and soaps.
• Jasmine oil is an essential oil that is valued for its soothing, relaxing, antidepressant qualities.
• Jasmine blends well with other perfumes.
• It is much used in modern perfumery and cosmetics and has become popular in air fresheners, anti-perspirants, talcum powders, shampoos and deodorants.

10.9 Traditional Systems of Medicines

India has a rich medicinal heritage. A number of Traditional Systems of Medicine (TSM) are practiced in India some of which come from outside India. TSM in India can be broadly classified into institutionalized or documented and non-institutionalized or oral traditions. Institutionalized Indian systems include Siddha and Ayurveda which are practiced for about two thousand years. These systems have prescribed texts in which the symptoms, disease diagnosis, drugs to cure, preparation of drugs, dosage and diet regimes, daily and seasonal regimens are documented. Non-institutional systems, whereas, do not have such records and are practiced by rural and tribal peoples across India. The knowledge is mostly held in oral form. The TSM focus on healthy lifestyle and healthy diet for maintaining good health and disease reversal.

Siddha System of Medicine

Siddha is the most popular, widely practiced and culturally accepted system in Tamil Nadu. It is based on the texts written by 18 Siddhars. There are different opinions on the constitution of 18 Siddhars. The Siddhars are not only from Tamil Nadu, but have also come from other countries. The entire knowledge is documented in the form of poems in Tamil. Siddha is principally based on the Pancabūta philosophy. According to this system three humors namely Vātam, Pittam and Kapam that are responsible for the health of human beings and any disturbance in the equilibrium of these humors result in ill health. The drug sources of Siddha include plants, animal parts, marine products and minerals. This system specializes in using minerals for preparing drugs with the long shelf-life. This system uses about 800 herbs as source of drugs. Great stress is laid on disease prevention, health promotion, rejuvenation and cure.

Ayurveda System of Medicine

Ayurveda is supposed to have originated from Brahma. The core knowledge is documented by Charaka, Sushruta and Vagbhata in compendiums written by them. This system is also based on three humor principles namely, Vatha, Pitha and Kapha which would exist in equilibrium for a healthy living. This system uses more of herbs and few animal parts as drug sources. Plant sources include a good proportion of Himalayan plants. The Ayurvedic Pharmacopoeia of India lists about 500 plants used as source of drugs.

Folk System of Medicine

Folk systems survive as an oral tradition among innumerable rural and tribal communities of India. A consolidated study to document the plants used by ethnic communities was launched by the Ministry of Environment and Forests, Government of India in the form of All India Coordinated Research Project on Ethnobiology. As a result about 8000 plant species have been documented which are used for medicinal purposes. The efforts to document in several under-explored and unexplored pockets of India still continue. Major tribal communities in Tamil Nadu who are known for their medicinal knowledge include Irulas, Malayalis, Kurumbas, Paliyans and Kaanis.

10.10 Medicinal Plants

India is a treasure house of medicinal plants. They are linked to local heritage as well as to global-trade. All institutional systems in India primarily use medicinal plants as drug sources. At present, 90% collection of medicinal plants is from the non-cultivated sources. Growing demand for herbal products has led to quantum jump in volume of plant materials traded within and across the countries. Increasing demand exerts a heavy strain on the existing resources. Now efforts are being made to introduce cultivation techniques of medicinal plants to the farmers. Medicinal plants play a significant role in providing primary health care services to rural and tribal people. They serve as therapeutic agents as well as important raw materials for the manufacture of traditional and modern medicines. Medicinally useful molecules obtained from plants that are marketed as drugs are called Biomedicines. Medicinal plants which are marketed as powders or in other modified forms are known as Botanical medicines.

Keelaanelli

Botanical name: Phyllanthus amarus

Family: Euphorbiaceae (Now in Phyllanthaceae)

Origin and Area of cultivation: The plant is a native of Tropical American region and is naturalised in India and other tropical countries. It is not cultivated and is collected from moist places in plains. Phyllanthus maderspatensis is also commonly sold in the medicinal plant markets collected from non-forest areas as keelaanelli.

Active principle: Phyllanthin is the major chemical component.

Medicinal importance: Phyllanthus is a well-known hepato-protective plant generally used in Tamil Nadu for the treatment of Jaundice. Research carried out by Dr. S P Thyagarajan and his team from University of Madras has scientifically proved that the extract of P. amarus is effective against hepatitis B virus.

Nilavembu

Botanical name: Andrographis paniculata

Family: Acanthaceae

Andrographis paniculata, known as the King of Bitters is traditionally used in Indian systems of medicines.

Active principle: Andrographolides.

Medicinal importance: Andrographis is a potent hepatoprotective and is widely used to treat liver disorders. Concoction of Andrographis paniculata and eight other herbs (Nilavembu Kudineer) is effectively used to treat malaria and dengue.

Psychoactive Drugs

Phytochemicals/drugs from some of the plants alter an individual's perceptions of mind by producing hallucination are known as psychoactive drugs. These drugs are used in all ancient culture especially by Shamans and by traditional healers.

Opium Poppy

Botanical name: Papaver somniferum

Family: Papaveraceae

Origin and Area of cultivation: Opium poppy is native to South Eastern Europe and Western Asia. Madhya Pradesh, Rajasthan and Uttar Pradesh are the licenced states to cultivate opium poppy. Opium is derived from the exudates of fruits of poppy plants. It was traditionally used to induce sleep and for relieving pain. Opium yields Morphine, a strong analgesic which is used in surgery. However, opium is an addiction forming drug.

Cannabis or Marijuana

Botanical name: Cannabis sativa

Family: Cannabiaceae

Origin and Area of Cultivation: Marijuana is native to China. States such as Gujarat, Himachal Pradesh, Uttarkand, Uttarpradesh and Madhya Pradesh have legally permitted to cultivate industrial hemp/Marijuana.

The active principle in Marijuana is trans-tetrahydrocanabinal (THC). It possesses a number of medicinal properties:

• It is an effective pain reliever and reduces hypertension.
• THC is used in treating Glaucoma, a condition in which pressure develops in the eyes.
• THC is also used in reducing nausea of cancer patients undergoing radiation and chemotherapy.
• THC provides relief to bronchial disorders, especially asthma as it dilates bronchial vessels.

Because of these medicinal properties, cultivation of cannabis is legalized in some countries. However, prolonged use causes addiction and has an effect on individual's health and society. Hence most of the countries have banned its cultivation and use.

Table 1: Other Common Medicinal Plants

S.No.	Common Name	Tamil Name	Botanical Name	Family	Plant Part Used	Medicinal Uses
1.	Holy basil	Thulasi	Ocimum sanctum	Lamiaceae	Leaves and Roots	The leaves are stimulant, antiseptic, antihypertensive and anti-bacterial and expectorant used in bronchitis. Decoction of roots is given as a diaphoretic in malarial fever.
2.	Indian gooseberry	Nelli	Phyllanthus emblica	Phyllanthaceae	Fruit	It is a potent rejuvenator and immune modulator. It has anti-ageing properties. It helps to promote longevity, enhance digestion, treat constipation and reduce fever and cough.
3.	Indian Acalypha	Kupaimeni	Acalypha indica	Euphorbiaceae	Leaves	Used to cure skin diseases caused by ringworms. Powdered leaves are used to cure bedsores and infected wounds.
4.	Vilvam	Vilvam	Aegle marmelos	Rutaceae	Fruit	The unripe fruit is used to treat problems of stomach indigestion. It kills intestinal parasites.
5.	Veldt grape	Pirrndai	Cissus quadrangularis	Vitaceae	Stem and root	Paste obtained from the powdered stem and root of this plant is used in bone fractures. Whole plant is useful to treat asthma and stomach troubles.

Do You Know?

Narcotics Control Bureau (NCB): Drugs come in various forms and can be taken in numerous ways. Some are legal and others are not. Drug abuse and misuse can cause numerous health problems and in serious cases death can occur. The Narcotics Control Bureau (NCB) is the nodal drug law enforcement and intelligence agency of India and is responsible for fighting drug trafficking and the abuse of illegal substances.

10.11 Entrepreneurial Botany

Entrepreneurial Botany is the study of how new businesses are created using plant resources as well as the actual process of starting a new business. An entrepreneur is someone who has an idea and who works to create a product or service that people will buy, by building an organization to support the sales. Entrepreneurship is now a popular topic for higher secondary students, with a focus on developing ideas to create new ventures among the young people.

Vast opportunities are there for the students of Botany. In the present scenario students should acquire ability to merge skills and knowledge in a meaningful way. Converting botanical knowledge into a business idea that can be put into practice for earning a livelihood is the much-needed training for the students. Few examples for activities of entrepreneurship are: Mushroom cultivation, Single cell protein (SCP) production, Seaweed liquid fertilizer, Organic farming, Terrarium, Bonsai and Cultivation of medicinal and aromatic plants.

10.11.1 Organic Farming

Organic farming is an alternative agricultural system in which plants/crops are cultivated in natural ways by using biological inputs to maintain soil fertility and ecological balance thereby minimizing pollution and wastage. Indians were organic farmers by default until the green revolution came into practice. Use of biofertilizers is one of the important components of integrated organic farm management, as they are cost effective and renewable source of plant nutrients to supplement the chemical fertilizers for sustainable agriculture. Several microorganisms and their association with crop plants are being exploited in the production of biofertilizers. Organic farming is thus considered as the movement directed towards the philosophy of Back to Nature.

1. Organic Pesticide

Pest like aphids, spider and mites can cause serious damage to flowers, fruits, and vegetables. These creatures attack the garden in swarms, and drain the life of the crop and often invite disease in the process. Many chemical pesticides prove unsafe for human and the environment. It turns fruits and vegetables unsafe for consumption. Thankfully, there are many homemade, organic options to turn to war against pests.

2. Bio-pest Repellent

Botanical pest repellent and insecticide made with the dried leaves of Azadirachta indica.

Preparation of Bio-pest repellent:

1. Pluck leaves from the neem tree and chop the leaves finely.
2. The chopped up leaves were put in a 50-liter container and fill to half with water; put the lid on and leave it for 3 days to brew.
3. Using another container, strain the mixture which has brewed for 3 days to remove the leaves, through fine mesh sieve.
4. The filtrate can be sprayed on the plants to repel pests.
5. To make sure that the pest repellent sticks to the plants, add 100 ml of cooking oil and the same amount of soap water. (The role of the soap water is to break down the oil, and the role of the oil is to make it stick to the leaves.)
6. The stewed leaves from the mixture can be used in the compost heap or around the base of the plants.

Summary

• Early civilization in different parts of the world has domesticated different species of plants for various purposes. Based on their utility, the economically useful plants are classified into food plants, fibre plants, timber plants, medicinal plants, and plants used in paper industries, dyes and cosmetics.
• Food base of majority of the population depends on very few Cereals, Millets, Pulses, Vegetables, Fruits, Nuts, Sugars, Oil seeds, Beverages, Spices and Condiments.
• Oils can be classified into two types namely, essential oils and vegetable oils.
• The oil yielding plants are groundnut and sesame. The oils are used in cooking, making soaps and other purposes.
• Beverages contain alkaloids that stimulate central nervous system.
• Spices were used throughout the world for several years. Cardamom is 'Queen of Spices' used for flavouring confectionaries and beverages. Black pepper is King of Spices.
• Botanically a fibre is a long, narrow, thick walled cell. Cotton and Jute are fibre yielding plants.
• Teak is wood used for making furniture.
• Rubber is produced from the latex of Hevea brasiliensis.
• Paper production is a Chinese invention.
• Dyes have been used since ancient times. The orange dye henna is from the leaves of Lawsonia.
• Perfumes are volatile and aromatic in nature, manufactured from essential oils which are found at different parts of the plant.
• Medicinal plants serve as therapeutic agents. Medicinally useful molecules obtained from these plants that are marketed as drugs are called Biomedicines. Whereas phytochemicals from some of the plants which alter an individual's perceptions of mind by producing hallucination are known as psychoactive drugs.
• Entrepreneurial Botany is the study of how new businesses are created using plant resources as well as the actual process of starting a new business.

Evaluation

Exercise 1. MCQ – Consider the following statements

1. Consider the following statements and choose the right option.
(1) Cereals are members of grass family.
(2) Most of the food grains come from monocotyledon.

a. (1) is correct and (2) is wrong b. Both (1) and (2) are correct c. (1) is wrong and (2) is correct d. Both (1) and (2) are wrong

2. Assertion: Vegetables are important part of healthy eating.
Reason: Vegetables are succulent structures of plants with pleasant aroma and flavours.

a. Assertion is correct, Reason is wrong b. Assertion is wrong, Reason is correct c. Both are correct and reason is the correct explanation for assertion. d. Both are correct and reason is not the correct explanation for assertion.

3. Groundnut is native of ___

a. Philippines b. India c. North America d. Brazil

4. Statement A: Coffee contains caffeine.
Statement B: Drinking coffee enhances cancer.

a. A is correct, B is wrong b. A and B – Both are correct c. A is wrong, B is correct d. A and B – Both are wrong

5. Tectona grandis is coming under family

a. Lamiaceae b. Fabaceae c. Dipterocarpaceae d. Ebenaceae

6. Tamarindus indica is indigenous to

a. Tropical African region b. South India, Sri Lanka c. South America, Greece d. India alone

7. New world species of cotton

a. Gossypium arboretum b. G. herbaceum c. Both a and b d. G. barbadense

8. Assertion: Turmeric fights various kinds of cancer.
Reason: Curcumin is an anti-oxidant present in turmeric.

a. Assertion is correct, Reason is wrong b. Assertion is wrong, Reason is correct c. Both are correct d. Both are wrong

9. Find out the correctly matched pair.

a. Rubber – Shorea robusta b. Dye – Lawsonia inermis c. Timber – Cyperus papyrus d. Pulp – Hevea brasiliensis

10. Observe the following statements and pick out the right option:
Statement 1 – Perfumes are manufactured from essential oils.
Statement 2 – Essential oils are formed at different parts of the plants.

a. Statement 1 is correct b. Statement 2 is correct c. Both statements are correct d. Both statements are wrong

11. Observe the following statements and pick out the right option:
Statement 1: The drug sources of Siddha include plants, animal parts, ores and minerals.
Statement 2: Minerals are used for preparing drugs with long shelf-life.

a. Statement 1 is correct b. Statement 2 is correct c. Both statements are correct d. Both statements are wrong

12. The active principle trans-tetra hydro canabial is present in

a. Opium b. Curcuma c. Marijuana d. Andrographis

13. Which one of the following matches is correct?

a. Palmyra - Native of Brazil b. Saccharum - Abundant in Kanyakumari c. Stevioside - Natural sweetener d. Palmyra sap - Fermented to give ethanol Exercise 14. Short Answer

14. Write the cosmetic uses of Aloe.

15. What is pseudo cereal? Give an example.

16. A person got irritation while applying chemical dye. What would be your suggestion for alternative?

17. Discuss which wood is better for making furniture.

17. Name the humors that are responsible for the health of human beings.

18. Give definitions for organic farming.

19. Which is called as the "King of Bitters"? Mention their medicinal importance.

20. Differentiate bio-medicines and botanical medicines.

Exercise Long Answer Questions

21. Write the origin and area of cultivation of green gram and red gram.

22. What are millets? What are its types? Give example for each type.

24. If a person drinks a cup of coffee daily it will help him for his health. Is this correct? If it is correct, list out the benefits.

25. Enumerate the uses of turmeric.

26. What is TSM? How is it classified and what does it focus on?

27. Write the uses of nuts you have studied.

28. Give an account on the role of Jasminum in perfuming.

29. Give an account of active principle and medicinal values of any two plants you have studied.

30. Write the economic importance of rice.

31. Which TSM is widely practiced and culturally accepted in Tamil Nadu? Explain.

32. What are psychoactive drugs? Add a note on Marijuana and Opium.

33. What are the King and Queen of spices? Explain about them and their uses.

34. How will you prepare an organic pesticide for your home garden with the vegetables available from your kitchen?

Glossary

Alzheimer's disease A type of dementia that causes problems with memory, thinking and behavior. Antiperspirant Products whose primary function is to inhibit perspiration/sweat. Anti-inflammatory The property of a substance or treatment that reduces swelling. Antioxidant A substance that scavenges free radicals. Carminative A drug causing expulsion of gas from the stomach or bowel. Cirrhosis A chronic liver disease typically caused by alcoholism or hepatitis. Confectionary A place where confections/sweets are kept or made. Cosmetics Substances or products used for personal grooming. Diuretic Substance that promote urine production. Ethnobiology Ethnobiology is the study of relationships between peoples and plants. Fixative A substance used to reduce the evaporation rate and improve stability when added to more volatile components. Lubricant Oily substance that reduces friction. Malnutrition Deficiencies, excesses or imbalances in a person's intake of energy and/or nutrients. Odour Smell (pleasant or unpleasant). Perfumery The art or process of making perfume. Pharmacopoeia Is a book containing directions for the identification of compound medicines, and published by the authority of a government or a medical or pharmaceutical society. Seasoning The processing of food with spices and condiments to enhance the flavour.

ICT Corner – Economically Useful Plants

Activity 1: Let us know about agriculture in detail

Steps:

1. Type the URL or scan the QR code to open the activity page then Introduction page will open.
2. Select Package of Practices to know the various methods of agricultural crops breeding system.
3. Click on Chat with expert – helps the farmers to clarify their doubts.
4. Click on Videos to know about the agricultural methods visually through videos.

URL: https://play.google.com/store/apps/details?id=com.criyagen

Activity 2: Let us know about the Agri book in detail

Steps:

1. Type the URL or scan the QR code to open the activity page then Introduction page will open.
2. Click on Agriculture – it will display the approaches to cultivate the planted paddy, cotton and sugarcane.
3. Click on Horticulture – it will display the approaches to cultivate the agricultural crops like tea, coffee.
4. Click on Organic Farming – it will explain the Traditional method of farming and Traditional Fertilizers.
5. Click on Forestry – it will explain the gardening methods about plants.

URL: https://play.google.com/store/apps/details?id=com.agribook.venkatmc.agri

Biology Botany Practicals

General Instructions

Laboratory is a place where ideas and concepts can be tested through experiments. Laboratory investigations in biology increase the reasoning abilities, brings scientific attitude in a learner and also helps in acquisition of skills of scientific processes.

The practical work includes:

• Study of permanent slides
• Microscopic preparation of slides
• Study of preserved and fresh specimens
• Section, cutting and mounting
• Analysing the problem and solving it
• Physiological experiments, etc.

In order to perform experiments successfully, a learner needs to go to the Biology Laboratory well prepared. This includes the following:

1. Laboratory record book
2. Dissection box
3. Laboratory manual
4. A laboratory coat or apron
5. A hand towel
6. Drawing pencil (HB) and pencil eraser to record various experiments and to draw diagrams
7. Any item more as per the instructions of the teacher

While in the laboratory, a student should be very careful and methodical. One should listen carefully to the instructions given by the teacher/instructor before performing an experiment. Maintain a complete silence and working atmosphere in the laboratory. Record keeping is most important in practical. Diagrams should be correctly drawn and well labelled. Always get the signature of the teacher in the practical note book on each day after the practical class.

1 – Preparation and Demonstration of Slides

Exercise 1: T.S of Anther

Aim: To study and identify the given slide – T.S of Anther.

Principle: Androecium is made up of stamens. Each stamen possesses an anther and a filament. Anther bears pollen grains which represent the male gametophyte.

Requirements: Anther of Datura metel, glycerine, safranin, slide, cover slip, blade, brush, needle to prepare temporary slides, permanent slide of T.S. of mature anther and compound microscope.

Collect buds and opened flowers of Datura metel. Dissect the stamens, separate the anthers and take thin sections and observe the structure under the microscope. Record the various stages of anther from your observation.

Diagnostic Features:

• A mature anther is bilobed (dithecous) and the two lobes are joined by a connective.
• Each anther lobe has two pollen chambers in which pollen grains are produced.
• A microsporangium or pollen sac is surrounded by four wall layers. They are epidermis, endothecium, middle layers and tapetum.
• Centre of the microsporangium (pollen sac) is filled with haploid pollen grains.

Exercise 2: L.S of an Angiospermic Ovule

Aim: To study and identify the L.S. of an Angiospermic Ovule.

Principle: In female reproductive part of a flower, the basal swollen part is ovary. The ovules are present inside the ovary, later they develop to seed.

Requirement: Permanent slide of L.S. of Ovule, microscope.

Diagnostic Features:

• Ovule or megasporangium is protected by one/two coverings called integuments.
• The stalk of the ovule is called funicle.
• The point of attachment of funicle to the body of the ovule is known as hilum.
• The body of the ovule is made up of a central mass of parenchymatous tissue called nucellus.
• The integuments form a pore called micropyle and the region opposite to the micropyle is called as chalaza.
• The nucellus has a large, oval, sac like structure towards the micropylar end called embryo sac.
• A mature ovule has 8 nuclei in its embryo sac.

Exercise 3: T.S. of Nerium Leaf

Aim: To observe and understand the xerophytic adaptations found in Nerium leaves for living in dry or xeric habitat.

Principle: The plants which are living in dry or xeric condition are known as Xerophytes.

Requirements: Nerium leaf, few pieces of carrot/pith/styrofoam, blade, brush, needle, compound microscope, glycerine, coverslip, wash glass, microslide, safranin solution, petri dish, etc.

Diagnostic Features:

• Presence of multilayered epidermis with thick cuticle.
• Sunken stomata are present only in the lower epidermis.
• Mesophyll is well differentiated into palisade and spongy parenchyma.
• Mechanical tissues are well developed.

Procedure:

1. Start cutting transverse sections of Nerium leaf placing it in between a piece of carrot.
2. Select the thinnest section of the material with the help of a delicate brush.
3. Take a clean watch glass with water, transfer thin sections of the material.
4. Put a few drops of safranin stain in the watch glass with water. Leave it for 3-5 minutes.
5. Drain off stain and wash with water if necessary.
6. Put the thinnest section in the centre of the slide.
7. Put a drop of glycerine over the material.
8. Cover it with a coverslip with the help of needle.
9. Observe it under a compound microscope.

2 – Fresh or Preserved Specimens and Models/Photographs/Charts

Exercise 4: Adaptations of flowers for pollination by different agents

Aim: To study the adaptations in flowers for pollination by different agents (wind and insects).

Principle: The process of transfer of pollen grains from the anther to stigma of a flower is called pollination.

Requirements: Fresh flowers of maize or any other cereal/gram, any insect pollination flowers like Salvia, Calotropis, Ocimum and Asteraceae flowers.

Place the given flower on a slide and observe it with the help of hand lens. Note down the adaptations of the flowers meant for pollination by the external agents.

5A. Wind Pollinated Flowers – Anemophily

Diagnostic Features:

• The flowers are small, inconspicuous, colourless, odourless and nectarless.
• Anthers and stigmas are commonly exerted.
• Pollen grains are light, small, powdery and produced in large numbers.
• The stigmas are large, sometimes feathery and branched adapted to catch the pollens.

5B. Insect Pollinated Flowers – Entomophily

Diagnostic Features:

• The flowers are showy, brightly coloured and scented.
• The flowers produce nectar or edible pollen.
• Anthers and stigmas are commonly inserted.
• Stigmas are usually unbranched and flat or lobed.

Exercise 5: Dicot Seed

Aim: To study and identify the Dicot seed.

Principle: The fertilized ovule is called seed and possesses an embryo, endosperm and a protective coat. Seeds may be endospermous or non endospermous.

Requirements: Chick pea, bowl, water.

Procedure: Soak the seeds of chick pea or gram in water for 2–3 hours. Drain the water and place the seeds in a moist cotton cloth for 2–3 days. Observe for germination. Select some sprouted seeds, observe under a dissection microscope and record the parts.

Diagnostic Features:

• Seeds of gram have two cotyledons and an embryonal axis.
• Each seed is covered by two seed coats: (a) Testa – outer coat and (b) Tegmen – inner coat.
• The embryonal axis consists of radicle and plumule.
• The portion of the embryonal axis above the level of cotyledons is called epicotyl. It terminates into the plumule.
• The portion of the embryonal axis below the level of cotyledons is called hypocotyl. It terminates into the radicle or root tip.

Exercise 6: E. coli Cloning Vector (pBR 322)

Aim: To study and identify the features of cloning vector – pBR 322.

Principle: Vectors are used as carriers to deliver the desired foreign DNA into a host cell.

Requirements: Models/Photographs/Pictures of E. coli Cloning vector pBR 322.

Diagnostic Features:

• pBR 322 plasmid is a reconstructed plasmid containing 4361 base pairs and most widely used as cloning vector.
• In pBR, p denotes plasmid and B and R respectively denote the notes of scientists Boliver and Rodriguez who developed the plasmid.
• The number 322 is the number of plasmids developed from their laboratory.
• It contains two different antibiotic resistance genes and recognition site for several restriction enzymes (Hind III, Eco R I, Bam H I, Sal I, Pvu II, Pst I, Cla I), Ori and antibiotic resistance genes (ampR and tetR).
• Rop codes for the proteins involved in the replication of the plasmid.

Exercise 7: Plant Tissue Culture – Callus with Plantlets

Aim: To study and identify the Callus with plantlets.

Principle: Growing the plant cells, tissues and organs in an artificial, synthetic medium under controlled conditions is called plant tissue culture. The technique of cloning plant is easier than animals because plant cells are simple in structure and most plant cells show totipotency (i.e., ability to regenerate from cells).

Requirements: Model/Photograph/Picture of callus with plantlets.

Diagnostic Features:

• The callus is an unorganized mass of undifferentiated tissue.
• The mechanism of callus formation is that auxin induce cell elongation and cytokinin induces cell division as a result of which masses of cells are formed.
• Roots and shoots are differentiated from the callus.

Exercise 8: Types of Ecological Pyramid

Aim: To study and identify the different types of ecological pyramids.

Principle: The relationship between different trophic levels in an ecosystem when shown diagrammatically appear as 'ecological pyramids'. In these ecological pyramids, the successive tiers represent successive trophic levels towards the apex. The base of the pyramid is of producers, the next one above it is of herbivores and the top tiers are of carnivores. The top most or apex represents the tertiary or top level consumers.

Requirements: Models/Photographs/Pictures of different types of ecological pyramid.

8A. Pyramid of Numbers

The number of organisms that are present in successive trophic levels of an ecosystem is shown in the pyramid of numbers of a grassland ecosystem. There is a gradual decrease in the number of organisms in each trophic level from producers to primary consumers, then to secondary consumer, and finally to tertiary consumers. Therefore, pyramid of number in grassland ecosystem is always upright.

• T1 - Producers
• T2 - Herbivores
• T3 - Secondary consumers
• T4 - Tertiary consumers

8B. Pyramid of Biomass

Pyramid of biomass represents the total biomass or standing crop (dry weight) of organisms in each trophic level at a particular time. In aquatic ecosystem, the bottom of the pyramid is occupied by the producers, which comprises very small organisms (algae and phytoplanktons) possessing the least biomass and so the value gradually increases towards the tip of the pyramid. Therefore, here the pyramid of biomass is always inverted in shape.

• T1 - Producers
• T2 - Herbivores
• T3 - Secondary consumers

8C. Pyramid of Energy

Pyramid of energy represents the number of joules transferred from one trophic level to next. The bottom of the pyramid of energy is occupied by the producers. There is a gradual decrease in energy transfer at successive trophic levels from producers to the upper levels. Therefore pyramid of energy is always upright.

3 – Solving the Problems – Genetic and Ecology

Exercise 9: To verify Mendel's Monohybrid Cross

Note: Students have to work in pairs to perform this experiment and record the data in the observation and record note book with the help of the teacher. Need not consider this Monohybrid cross experiment for Board Practical Examination.

Aim: To verify Mendel's Monohybrid cross.

Principle: When two purelines with contrasting traits of a particular character (phenotype) are crossed to produce the next generation (F1 generation), all the members of the progeny are of only one phenotype, that is of one of the two parents. The phenotype that appears is called dominant and the one that does not appear is called recessive. When the F1 plants are selfed, the progeny (F2 generation) is in the ratio of 3 dominant : 1 recessive (75% : 25%). This reappearance of the recessive phenotype in F2 generation, verifies Mendel's Monohybrid cross.

Requirements: 64 yellow and 64 green plastic beads, all of exactly same shape and size. Plastic beakers, petri dish and a napkin/hand towel.

Procedure:

1. Put 64 yellow beads in one beaker and 64 green beads in the other to represent male and female gametes respectively. Let the yellow bead be indicated by 'Y' and the green bead by 'y'.
2. Take a bead from each container and place them together (it represents fertilization) on the hand towel spread before you on the table.
3. Just like the previous step, continue to pick beads and arrange them in pairs. Thus 64 pairs of beads are obtained representing the 64 heterozygous F1 progeny.
4. Put 32 F1 progeny in one petridish and the remaining 32 in another petridish (representing the F1 males and females).
5. To obtain the F2 generation, the student should withdraw one bead from one beaker labelled male and one from the other beaker labelled female keeping his/her eyes closed (to ensure randomness) and put them together on the hand towel spread over the table. Continue this process till all the beads are paired. Thus 64 offsprings of F2 progeny are obtained.
6. Note the genotype (YY or Yy or yy) of each pair and their possible phenotype.
7. Pool all the data and calculate the genotypic and phenotypic ratios.

Observation:

Generation	Phenotypic Ratio	Genotypic Ratio
F1
F2

Inference: The results are so because when the F1 individuals are crossed together to raise the F2 generation, each F1 individual produces two types of gametes: 50% having dominant allele and the remaining 50% having recessive allele. These gametes undergo random fusion during fertilization to produce the F2 generation. Among these, proportion of dominant phenotype would be YY + Yy = yellow and recessive phenotype yy = green, which occur in 3:1 or 75% : 25% ratio.

Precautions:

1. Take a sufficiently large number of seeds for analysis to minimise the error.
2. Observe the contrasting form of trait carefully.

Exercise 10: Analysis of Seed Sample to Study Mendelian Dihybrid Ratio

Aim: To analyse seed sample of pea for Mendelian dihybrid ratio of 9:3:3:1.

Principle: In a dihybrid cross, the segregation of one gene pair is independent of the segregation of the other pair. It means that when the factors (genes) for different characters inherited from parents do not remain linked in the offsprings, but their distribution in the gametes and in the progeny of subsequent generations is independent of each other.

Requirement: Plastic beakers, Pea seed samples or plastic beads, tray, petri dishes, notebook, pencil/pen.

Procedure:

1. Take a lot of about 160 Pea seeds or plastic beads in a tray.
2. Separate out yellow round, yellow wrinkled, green round and green wrinkled and put them in separate petridishes.
3. Note down the number of seeds in each plate and find out their approximate ratio.

Observation:

Total Number of Seeds	Yellow Round	Yellow Wrinkled	Green Round	Green Wrinkled	Approximate Ratio
160	90	30	30	10	9:3:3:1

Inference: The ratio of yellow round : yellow wrinkled : green round : green wrinkled is approximately 9:3:3:1 which is exactly the same as obtained by Mendel for a dihybrid cross. This indicates that the contrasting genes for seed colour and seed shape show an independent assortment in the population of pea seeds.

Exercise 11: Flow of Energy and Ten Percent Law

Aim: To understand the unidirectional flow of energy in an ecosystem and transfer of energy follows the 10% law.

Principle: The student studies about flow of energy and that only about 10% of energy is made available to the next trophic level. Large amount of energy about 90% is lost at each trophic level in a food chain.

Problem: Analyse the food chain given below and find out the amount of energy received by the organism in third trophic level.

Given: The amount of energy in the producers, i.e. grass = 30,000 J.

Solution:

• T1 – Grass (Producer) = 30,000 J of energy
• T2 – Rabbit (Primary Consumer) = ?
• T3 – Snake (Secondary Consumer) = ?

According to the ten percent law, during the transfer of energy, only about 10% of the energy flows from each trophic level to the next lower trophic level.

So T2 Rabbit (primary consumer) receives = 30,000 × 10/100 = 3,000 J

So T3 Snake (Secondary consumer) receives = 3,000 × 10/100 = 300 J

Answer: The third trophic level T3 – (Snake) receives 300 J of energy.

Exercise 12: Determination of Population Density and Percentage Frequency by Quadrat Method

Note: Teachers can take the students to open space and teach them how to construct plots/quadrats and to record the number of individuals of each plant species occurring in the quadrat. Examiner need not consider this experiment for Board Practical Examinations.

Aim: To study population density and percentage frequency of different plant species of a given area by quadrat method.

Principle: The number of individuals in a population never remains constant. It may increase or decrease due to many factors like birth rate, death rate, migration, etc. The number of individuals of a species present per unit area or space of a given time is called population density. The population density and percentage frequency of different plant species can be determined by laying quadrats/segments of suitable size and recording of the number of individuals of each species occurring in the quadrat.

Requirements: Metre scale, string or cord, hammer, nails, paper, pencil, etc.

Procedure:

1. In the selected site of study, hammer the nails firmly in the soil without damaging the vegetation.
2. Fix four nails to make a square plot.
3. Tie each end of the nails using a thread, to make 1m × 1m plot.
4. If the number of plants in the plot is large, the plot can be divided into quadrats.
5. Count the number of individuals of a species "A" present in the first quadrat and record the data in the table.
6. Similarly count the individuals of the species "A" in other quadrats respectively and record the data in the table.
7. Count the number of individuals of a species "B" present in all quadrats and record the data in the table.
8. Repeat the same procedure for other species and record the data in the table.

Precautions:

1. The measurement of quadrat should be accurate.
2. The string or cord used should not be very thick.

Exercise 13: Chromosomal Aberrations – Deletion, Duplication and Inversion

Aim: To understand the abnormality in the chromosomal structure in an organism.

Principle: To study about the chromosomal aberration which can occur due to ionizing radiations or chemicals. On the basis of breaks and reunions in the chromosomal segment different types of aberrations can be recognized.

Requirements: Copper wire, Alphabets marked (A to H) yellow colour beads denotes gene, and red colour bead without alphabet denote centromere.

Procedure:

1. Make a normal chromosome model using copper wire and yellow beads and place it on the table. In the model chromosome with gene sequence A to H, along with centromere (red bead).
2. For Deletion – Give yellow colour beads without one or more marked alphabets A to H (The lack of any one or more beads denotes deletion type of chromosomal aberration).
3. For Duplication – Give yellow colour beads with addition of one or more marked alphabets A to H (The repetition of one or more beads denotes duplication type of chromosomal aberration).
4. For Inversion – Give yellow colour beads which marked alphabets from A to H as in normal chromosome (There is no addition or deletion of beads, so the students can construct the inverted segment of the chromosome using the given beads).

13A. Chromosomal Aberration – Deletion

Reasons:

1. The deletion of the chromosomal segment A and D.
2. When there is a loss of a segment of the genetic material in a chromosome it is called deletion.

Significance: Most of the deletions lead to death of an organism.

13B. Chromosomal Aberration – Duplication

Reasons:

1. When a segment of a chromosome is present more than once in a chromosome, then it is called duplication (Tandem duplication).
2. The order of the genes in a chromosome is A, B, C, D, E, F, G, H and I. Due to aberration, the genes B and C are duplicated and the sequence of genes becomes A, B, C, B, C, D, E, F, G, H and I.

Significance: Some duplications are useful in the evolution of the organism.

13C. Chromosomal Aberration – Inversion

Identification: The given genetic problem is identified as inversion type of chromosomal aberration.

Reasons:

1. When the order of genes in a chromosomal segment is reversed due to rotation by an angle of 180°, it is called inversion.
2. The order of genes in a chromosome is A, B, C, D, E, F, G, H and I. Due to aberration, the sequence of genes become A, D, C, B, E, F, G, H and I.

Significance: Sometimes inversion is responsible for evolution of the organism.

Exercise 14: Genetic/Linkage Maps

Aim: To understand the frequency of recombination between the gene pairs on the same chromosome.

Principle: To analyse the relative distance between the various genes and map their position in the chromosome, which is called genetic or linkage maps.

Problem: There are three linked genes A, B and C in a chromosome. Percentage of crossing over (Recombination frequency) between A and B is 20, B and C is 28 and A and C is 8. What is the sequence of genes on the linkage map?

Given: Percentage of crossing over between the 3 linked genes: A–B = 20%, B–C = 28% and A–C = 8%.

Reasons:

1. The frequency of crossing over is directly proportional to the relative distance of the genes on the chromosomes.
2. More crossing over = More distance between two genes and Less crossing over = Less distance between the two genes.

Solution: In the above problem, the sequence of the genes on the linkage map is B, A, C.

4 – Experiments

Exercise 15: Study of Pollen Germination on a Slide

Note: Pollen germination can be studied by dusting some pollens from common flowers like Crotalaria, Hibiscus, Pisum, etc. on a glass slide containing a drop of 10% sugar solution or tender coconut water or any nutrient medium. Observe the slide after about 10 to 15 minutes under the low power of compound microscope.

Aim: To study the pollen germination on a slide.

Requirements: Fresh seasonal flowers, cavity slide, cover slip, compound microscope, sucrose, boric acid, distilled water, beakers, etc.

Procedure:

1. Prepare a nutrient solution by dissolving 1 gm. of sucrose / 1 gm. of boric acid in 100 ml. of distilled water.
2. Take a clean cavity slide and put a few drops of nutrient solution in the cavity of the slide.
3. Dust a few pollen grains from the stamen of a mature flower on it.
4. View the slide in the microscope after 5 minutes and then observe it regularly for about half an hour.

Observation: In nutrient medium, the pollen grains germinate. The tube cell enlarges and comes out of the pollen grain through one of the germ pores to form a pollen tube. The tube nucleus descends to the tip of the pollen tube. The generative cell also passes into it. It soon divides into two male gametes.

Inference: Different stages of germinating pollens are observed. Some pollens are in their initial stage of germination while others have quite long pollen tube containing tube nucleus and two male gametes.

Precautions:

1. Flowers should be freshly plucked.
2. Use clean cavity slide to observe the pollen grains.
3. The slides should not be disturbed, otherwise position of pollen grains will get changed.

Exercise 16: Study of pH of Different Types of Soil

Some nutrients become toxic in higher concentration. Therefore pH of the soil is an important chemical property of the soil. Plants thrive well in neutral or slightly acidic soils. The pH of the soil determines the types of soil organisms and also controls the solubility of different nutrients. The pH of soil ranges from 0 to 14.

• pH level 7 – Neutral soil
• pH level below 7 – Acidic soil
• pH level above 7 – Alkaline soil
• Optimum pH for plant growth ranges from 5.5 to 7.

Aim: To study pH of different types of soil.

Requirements: Soil samples (from two different sites such as crop soil, garden soil, roadside soil, pond soil, river bank soil), test tubes, funnel, filter papers, pH papers of different range, distilled water, beaker.

Procedure:

1. Dissolve one tablespoon or 1 gram of soil from each soil sample in 100 ml of distilled water in separate beakers.
2. Stir the solutions well and keep aside for half an hour to settle down the suspended particles.
3. Filter off each solution separately in different test tubes.
4. Dip a small piece of broad range pH paper on each of the solution.
5. Match the colour of the pH paper with the colour scale given on the pH paper booklet. This gives an approximate pH.

Observation:

S. No.	Soil Sample	pH Value
1
2
3

Inference: Thus the pH value of different soil samples required for plant growth can be determined.

Precautions:

1. Wash the glassware thoroughly and get it dried before the experiment.
2. Dry the pH papers before comparing the colour with the colour scale.
3. Match the colour carefully and determine pH accurately.

Exercise 17: Isolation of DNA from Plant Materials

DNA is one of the nucleic acids found in living systems. DNA acts as the genetic material in most of the organisms.

Principle: Recombinant DNA technology has allowed breeders to introduce foreign DNA in other organisms including bacteria, yeast, plants and animals. Such organisms are called Genetically Modified Organisms (GMOs). Thus rDNA technology involves isolation of DNA from a variety of sources and formation of new combination of DNA.

Aim: To isolate DNA from available plant materials such as spinach leaves, fresh green pea seeds, green papaya, etc.

Requirements: Plant materials, mortar and pestle, beakers, test tubes, ethanol, etc.

Procedure:

1. Take a small amount of plant material and grind it in a mortar with a little amount of water and sodium chloride.
2. Make it into a solution and filter it.
3. To this filtrate, add liquid soap solution or any detergent solution and mix it with a glass rod.
4. Then tilt the test tube and add chilled ethanol and leave it aside in the stand.
5. After half-an-hour we can observe the precipitated DNA as fine threads. DNA that separates can be removed by spooling.

Observation: DNA appears as white precipitate of very fine threads on the spool.

Inference: Thus DNA can be isolated from the plant cell nucleus by this technique.

Precautions:

1. All the glasswares must be thoroughly cleaned and dried.
2. The chemicals used for the experiments must be of standard quality.
3. If ordinary ethanol is used, the time duration for obtaining precipitated DNA may extend further.

5 – Economic Importance of Plants

Exercise 18: Economically Important Plant Products and Their Uses

Book-back Exercises — Questions & Answers

Answers generated strictly from the Samacheer Kalvi textbook content. Attempt each question first, then click "Show Answer" to check.

I. Choose the Correct Answer

1. Consider the following statements and choose the right option.
1) Cereals are members of grass family.
2) Most of the food grains come from monocotyledon.

a) (1) is correct and (2) is wrong b) Both (1) and (2) are correct c) (1) is wrong and (2) is correct d) Both (1) and (2) are wrong

Answer: b) Both (1) and (2) are correct

Explanation: All cereals are members of grass family (Poaceae). Cereals are monocotyledons, and rice, wheat and maize form the food base of majority of the population.

2. Assertion: Vegetables are important part of healthy eating.
Reason: Vegetables are succulent structures of plants with pleasant aroma and flavours.

a) Assertion is correct, Reason is wrong b) Assertion is wrong, Reason is correct c) Both are correct and reason is the correct explanation for assertion d) Both are correct and reason is not the correct explanation for assertion

Answer: a) Assertion is correct, Reason is wrong

Explanation: Vegetables are an important part of healthy eating and provide nutrients including potassium, fiber, folic acid and vitamins. However, it is edible fruits (not vegetables) that are described as fleshy structures with pleasant aroma and flavours.

3. Groundnut is native of ___

a) Philippines b) India c) North America d) Brazil

Answer: d) Brazil

Explanation: Groundnut (Arachis hypogaea) is native of Brazil. Portuguese introduced groundnut into Africa and the Spanish took it to South East Asia and India via Philippines.

4. Statement A: Coffee contains caffeine
Statement B: Drinking coffee enhances cancer

a) A is correct, B is wrong b) A and B – Both are correct c) A is wrong, B is correct d) A and B – Both are wrong

Answer: a) A is correct, B is wrong

Explanation: Coffee contains caffeine which enhances release of acetylcholine in the brain. Drinking coffee in moderation can lower the incidence of liver diseases and cancer — it does not enhance cancer.

5. Tectona grandis is coming under family

a) Lamiaceae b) Fabaceae c) Dipterocarpaceae d) Ebenaceae

Answer: a) Lamiaceae

Explanation: Tectona grandis (Teak) belongs to the family Lamiaceae. It is one of the best timbers of the world.

6. Tamarindus indica is indigenous to

a) Tropical African region b) South India, Sri Lanka c) South America, Greece d) India alone

Answer: a) Tropical African region

Explanation: Tamarind is native of tropical African region and was introduced into India several thousand years before.

7. New world species of cotton

a) Gossypium arboretum b) G. herbaceum c) Both a and b d) G. barbadense

Answer: d) G. barbadense

Explanation: G. hirsutum and G. barbadense are the New world species of cotton. G. arboretum and G. herbaceum are the old world species.

8. Assertion: Turmeric fights various kinds of cancer
Reason: Curcumin is an anti-oxidant present in turmeric

a) Assertion is correct, Reason is wrong b) Assertion is wrong, Reason is correct c) Both are correct d) Both are wrong

Answer: c) Both are correct

Explanation: Curcumin extracted from turmeric is a very good anti-oxidant which may help fight various kinds of cancer. Hence both the assertion and reason are correct.

9. Find out the correctly matched pair.

a) Rubber – Shorea robusta b) Dye – Lawsonia inermis c) Timber – Cyperus papyrus d) Pulp – Hevea brasiliensis

Answer: b) Dye – Lawsonia inermis

Explanation: An orange dye 'Henna' is obtained from the leaves and young shoots of Lawsonia inermis. Hevea brasiliensis yields rubber latex, and Cyperus papyrus is a pulp/paper plant.

10. Observe the following statements and pick out the right option from the following:
Statement 1 – Perfumes are manufactured from essential oils.
Statement 2 – Essential oils are formed at different parts of the plants.

a) Statement 1 is correct b) Statement 2 is correct c) Both statements are correct d) Both statements are wrong

Answer: c) Both statements are correct

Explanation: Perfumes are manufactured from essential oils which are volatile and aromatic. Essential oils are found at different parts of the plant such as leaves, flowers, fruits and wood.

11. Observe the following statements and pick out the right option from the following:
Statement 1: The drug sources of Siddha include plants, animal parts, ores and minerals.
Statement 2: Minerals are used for preparing drugs with long shelf-life.

a) Statement 1 is correct b) Statement 2 is correct c) Both statements are correct d) Both statements are wrong

Answer: b) Statement 2 is correct

Explanation: The drug sources of Siddha include plants, animal parts, marine products and minerals (not ores). This system specializes in using minerals for preparing drugs with long shelf-life, making Statement 2 correct and Statement 1 partially wrong.

12. The active principle trans-tetra hydro canabial is present in

a) Opium b) Curcuma c) Marijuana d) Andrographis

Answer: c) Marijuana

Explanation: The active principle in Marijuana (Cannabis sativa) is trans-tetrahydrocanabinal (THC).

13. Which one of the following matches is correct?

a) Palmyra - Native of Brazil b) Saccharum - Abundant in Kanyakumari c) Steveocide - Natural sweetener d) Palmyra sap - Fermented to give ethanol

Answer: d) Palmyra sap - Fermented to give ethanol

Explanation: According to the chapter, the sap of Palmyra inflorescence is processed to get palm jaggery or fermented to give toddy (which yields ethanol). Sugarcane is cultivated in all districts except Kanyakumari and Nilgiris of Tamil Nadu.

II. Answer Briefly

14. Write the cosmetic uses of Aloe.

Answer: 'Aloin' (a mixture of glucosides) and its gel are used as skin tonic. Aloe has a cooling effect and moisturizing characteristics, hence it is used in preparation of creams, lotions, shampoos, shaving creams, after shave lotions and allied products. It is used in gerontological applications for rejuvenation of aging skin. Products prepared from aloe leaves have emollient, antibacterial, antioxidant, antifungal and antiseptic properties.

15. What is pseudo cereal? Give an example.

Answer: The term pseudo-cereal is used to describe foods that are prepared and eaten as a whole grain, but are botanical outliers from grasses. They are gluten-free, whole-grain carbohydrates. Example: Quinoa (Chenopodium quinoa), which is actually a seed from a plant belonging to the family Amaranthaceae and has been eaten for 6000 years in the Andes hill region.

16. A person got irritation while applying chemical dye. What would be your suggestion for alternative.

Answer: The best alternative is Henna, obtained from the leaves and young shoots of Lawsonia inermis. The principal colouring matter of leaves 'lacosone' is harmless and causes no irritation to the skin. This natural orange dye has long been used to dye skin, hair and fingernails and is safe for use on the skin.

17. Name the humors that are responsible for the health of human beings.

Answer: In the Siddha system, the three humors responsible for the health of human beings are Vātam, Pittam and Kapam. In the Ayurveda system, they are known as Vatha, Pitha and Kapha. Any disturbance in the equilibrium of these humors results in ill health.

18. Give definitions for organic farming?

Answer: Organic farming is an alternative agricultural system in which plants/crops are cultivated in natural ways by using biological inputs to maintain soil fertility and ecological balance, thereby minimizing pollution and wastage. It is considered as the movement directed towards the philosophy of "Back to Nature."

19. Which is called as the "King of Bitters"? Mention their medicinal importance.

Answer: Andrographis paniculata (Nilavembu) is known as the "King of Bitters." Its active principle is Andrographolide. It is a potent hepatoprotective and is widely used to treat liver disorders. A concoction of Andrographis paniculata and eight other herbs (Nilavembu Kudineer) is effectively used to treat malaria and dengue.

20. Differentiate bio-medicines and botanical medicines.

Answer: Medicinally useful molecules obtained from plants that are marketed as drugs are called Biomedicines. Medicinal plants which are marketed as powders or in other modified forms are known as Botanical medicines. Thus, Biomedicines are isolated active chemical compounds used as drugs, whereas Botanical medicines are plant-based products used in their natural or modified plant form.

21. Write the origin and area of cultivation of green gram and red gram.

Answer: Green gram (Vigna radiata): It is a native of India; the earliest archaeological evidences are found in Maharashtra. It is cultivated in Madhya Pradesh, Karnataka and Tamil Nadu. Red gram / Pigeon pea (Cajanus cajan): It is the only pulse native to Southern India. It is mainly grown in Maharashtra, Andhra Pradesh, Madhya Pradesh, Karnataka and Gujarat.

22. What are millets? What are its types? Give example for each type.

Answer: The term millet is applied to a variety of very small seeds originally cultivated by ancient people in Africa and Asia. They are gluten free and have less glycemic index. Millets are of two types: (1) Millets – Example: Finger millet/Ragi (Eleusine coracana) and Sorghum (Sorghum vulgare). (2) Minor Millets – Example: Foxtail millet (Setaria italica) and Kodo millet (Paspalum scrobiculatum).

24. If a person drinks a cup of coffee daily it will help him for his health. Is this correct? If it is correct, list out the benefits.

Answer: Yes, drinking coffee in moderation provides the following health benefits: (1) Caffeine enhances release of acetylcholine in brain, which in turn enhances efficiency. (2) It can lower the incidence of fatty liver diseases, cirrhosis and cancer. (3) It may reduce the risk of type 2 diabetes.

25. Enumerate the uses of turmeric.

Answer: Uses of turmeric (Curcuma longa): (1) It is an important constituent of curry powders. (2) Used as a colouring agent in pharmacy, confectionery and food industry. (3) Rice coloured with turmeric is used in ceremonies as it is considered sacred. (4) Used for dyeing leather, fibre, paper and toys. (5) Curcumin extracted from turmeric is a very good anti-oxidant that may help fight various kinds of cancer. (6) It has anti-inflammatory, anti-diabetic, anti-bacterial, anti-fungal and antiviral activities. (7) It stops platelets from clotting in arteries, preventing heart attacks.

26. What is TSM? How does it classified and what does it focuses on?

Answer: TSM stands for Traditional Systems of Medicine. It is broadly classified into: (1) Institutionalized (documented) systems such as Siddha and Ayurveda, practiced for about two thousand years with prescribed texts. (2) Non-institutionalized (oral traditions) practiced by rural and tribal peoples without written records. The TSM focuses on healthy lifestyle and healthy diet for maintaining good health and disease reversal.

27. Write the uses of nuts you have studied.

Answer: Uses of Cashew nut (Anacardium occidentale): (1) Cashews are commonly used for garnishing sweets or curries. (2) Ground into a paste that forms a base of sauces for curries or sweets. (3) Roasted and raw kernels are used as snacks. Nuts in general are packed with healthy fats, fibre, protein, vitamins, minerals and antioxidants.

III. Answer in Detail

17. Discuss which wood is better for making furniture.

Answer: Teak (Tectona grandis, Family: Lamiaceae) is considered the best wood for making furniture. It is one of the best timbers of the world. The heartwood is golden yellow to golden brown when freshly sawn, turning darker when exposed to light. It is known for its durability as it is immune to the attack of termites and fungi. The wood does not split or crack and is a carpenter-friendly wood. It is also used in making boats, toys, plywood, door frames and doors, and was the chief railway carriage and wagon wood in India. Ship building and bridge-building also depends on teakwood.

28. Give an account on the role of Jasminum in perfuming.

Answer: Jasmine (Jasminum grandiflorum, Family: Oleaceae), as a floral perfume, ranks next to rose oil. The essential oil is present in the epidermal cells of the inner and outer surfaces of both the sepals and petals. One ton of Jasmine blossom yields about 2.5 to 3 kg of essential oil. Jasmine flowers have been used since ancient times in India for worship, ceremonial purposes, incense and fumigants, as well as for making perfumed hair oils, cosmetics and soaps. Jasmine oil is valued for its soothing, relaxing and antidepressant qualities. It blends well with other perfumes and is much used in modern perfumery, cosmetics, air fresheners, anti-perspirants, talcum powders, shampoos and deodorants. 'Madurai Malli' has been given the Geographical Indications (GI) mark due to its uniqueness and distinct fragrance.

29. Give an account of active principle and medicinal values of any two plants you have studied.

Answer: 1. Keelaanelli (Phyllanthus amarus, Family: Euphorbiaceae): Active principle – Phyllanthin is the major chemical component. Medicinally, it is a well-known hepato-protective plant used in Tamil Nadu for the treatment of Jaundice. Research by Dr. S P Thyagarajan has scientifically proved that the extract of P. amarus is effective against hepatitis B virus. 2. Nilavembu (Andrographis paniculata, Family: Acanthaceae): Active principle – Andrographolides. It is a potent hepatoprotective widely used to treat liver disorders. Concoction of Andrographis paniculata and eight other herbs (Nilavembu Kudineer) is effectively used to treat malaria and dengue.

30. Write the economic importance of rice.

Answer: Rice (Oryza sativa) is an important food crop of the world, occupying the second position in terms of area under cultivation and production, next to wheat. (1) Rice is the chief source of carbohydrate and is the easily digestible calorie-rich cereal used as a staple food in Southern and North East India. (2) Various rice products such as Flaked rice (Aval) and Puffed/parched rice (Pori) are used as breakfast cereal or snack food. (3) Rice bran oil obtained from rice bran is used in culinary and industrial purposes. (4) Husks are used as fuel, and in the manufacture of packing material and fertilizer.

31. Which TSM is widely practiced and culturally accepted in Tamil Nadu? – explain

Answer: The Siddha system of medicine is the most popular, widely practiced and culturally accepted system in Tamil Nadu. It is based on the texts written by 18 Siddhars. The entire knowledge is documented in the form of poems in Tamil. Siddha is principally based on the Pancabūta philosophy. According to this system, three humors namely Vātam, Pittam and Kapam are responsible for the health of human beings, and any disturbance in their equilibrium results in ill health. The drug sources of Siddha include plants, animal parts, marine products and minerals. This system specializes in using minerals for preparing drugs with long shelf-life, and uses about 800 herbs as source of drugs. Great stress is laid on disease prevention, health promotion, rejuvenation and cure.

32. What are psychoactive drugs? Add a note on Marijuana and Opium.

Answer: Phytochemicals/drugs from some plants that alter an individual's perceptions of mind by producing hallucination are known as psychoactive drugs. Opium (Papaver somniferum): Native to South Eastern Europe and Western Asia. Opium is derived from the exudates of fruits of poppy plants. It was traditionally used to induce sleep and relieve pain. Opium yields Morphine, a strong analgesic used in surgery. However, opium is an addiction-forming drug. Marijuana (Cannabis sativa): Native to China. The active principle is trans-tetrahydrocanabinal (THC). It is an effective pain reliever, reduces hypertension, treats glaucoma, reduces nausea in cancer patients undergoing chemotherapy and provides relief to bronchial disorders. However, prolonged use causes addiction and most countries have banned its cultivation.

📝 Summary

1. Economically useful plants are classified into food plants, fodder plants, fibre plants, timber plants, medicinal plants, and plants used in paper industries, dyes and cosmetics — all of which are directly or indirectly essential to all living forms on Earth.
2. Currently about 10,000 food plants are used, of which only around 1,500 species were brought under cultivation, yet the food base of the majority of the population depends on just three grass species: rice, wheat, and maize.
3. Cereals, all members of the grass family (Poaceae), are prominent food plants due to their adaptability, ease of cultivation, tillering property, compact storable grains, and high caloric value providing carbohydrates, proteins, fibres, vitamins, and minerals.
4. Rice (Oryza sativa), originating from South East Asia, occupies the second position in world cultivation and production next to wheat, and serves as a staple food in Southern and North East India with by-products like rice bran oil and husks used in industry and fuel.
5. The chapter covers a broad range of economically useful plant categories including spices and condiments, fibre, timber, latex, pulp wood, dyes, cosmetics, traditional medicines, medicinal plants, and entrepreneurial botany, reflecting the diverse roles plants play in human civilization.