5. Write short notes.

a. Meristematic tissue.

Ans: 

(i) Meristematic tissue is present in specific parts of a plant where growth takes place.

(ii) Cells of meristematic tissue contain thick cytoplasm, a conspicuous nucleus, and a thin cell wall and are compactly packed together.

(iii) Vacuoles are usually absent in these cells, and they are highly active.

(iv) The main function of meristematic tissue is to bring about plant growth.

(v) According to their location, meristematic tissues are of three types: apical meristem, intercalary meristem, and lateral meristem.

b. Xylem

Ans: 

(i) Xylem is a complex, permanent tissue in plants.

(ii) It consists of thick-walled dead cells.

(iii) The types of cells in xylem are trachytes, vessels, xylem fibres (dead cells), and xylem parenchyma (living cells).

(iv) Its structure is like interconnected tubes that conduct water and minerals only in an upward direction.

c. Striated muscles.

Ans: 

(i) The cells of striated muscles are long, cylindrical, multinucleate, and have no branches.

(ii) These are the alternate dark and light bands on these muscles.

(iii) As they are attached to bones, they are also called skeletal muscles.

(iv) They move at our will, hence they are called voluntary muscles. 

(v) Striated muscles bring about movements of arms and legs, running, speaking, etc.

d. Agro-complementary business.

Ans: 

(i) The businesses that are complementary to agriculture and generate supplementary income for the farmers are called agro-complementary businesses.

(ii) These include:

(a) Animal Husbandry: It is practised for milk production and for using the cattle as help in farming operations. e.g., cows and buffaloes are raised for milk, whereas bulls and male buffaloes are raised for pulling heavy loads.

(b) Poultry farming: This is the rearing of egg- and meat-producing chickens. Chickens raised for eggs are called layers, while those raised for meat are called broilers.

(c) Sericulture: This is the rearing of silkworms (moths) for silk production.       

e. Genetic engineering

Ans: 

(i) Genetic engineering is the deliberate modification of the characteristics of an organism by manipulating its genetic material.

(ii) An organism that is generated through genetic engineering is called a genetically modified organism (GMO).

(iii) Genetic engineering is applied in many fields like research, agriculture, industrial biotechnology, and medicine.

(iv) In agriculture, genetic engineering is used in the production of cash crops, the improvement of varieties of cash crops, and the increase in the ability of plants to withstand environmental stresses.

(v) In medicine, genetic engineering is used in laboratories for vaccine production, early diagnosis of congenital disease, organ transplant, cancer research, and the production of artificial skin, cartilage, etc.

f. Sericulture

Ans: 

(i) Sericulture is the rearing of silkworms (moths) for the production of silk.

(ii) Bombyx mori is the most commonly used variety of silkworm for this purpose.

(iii) The life cycle of the silkworm consists of four stages: egg, larva, pupa, and adult.

(iv) Thousands of eggs deposited by female moths are incubated artificially to shorten the incubation period.

(v) Larvae hatching from eggs are released on mulberry plants.

(vi) Larvae are nourished by feeding on mulberry leaves.

(vii) After feeding for 3–4 days, larvae move to branches of the mulberry plant.

(viii) The silk thread is formed from the secretion of their salivary glands.

(ix) Larvae spin this thread around themselves to form a cocoon. The cocoon may be spherical in nature.

(x) Ten days before the pupa turns into an adult, all the cocoons are transferred to boiling water.

(xi) Due to the boiling water, the pupa dies in the cocoon and the silk fibres become loose.

(xii) These fibres are unwound, processed, and reeled. Various kinds of fabric are woven from silk threads.

6. Explain the meaning of biotechnology and its impact on agricultural management with suitable examples.

Ans: The techniques of bringing about improvements in living organisms by artificial genetic changes and by hybridization for the welfare of humans are together called biotechnology. Impact of biotechnology on agricultural management:

(i) Genetically modified crops (GM crops) are being produced by introducing changes in the DNA of natural crops. Normally, such varieties are not found in nature. Thus, new varieties are produced artificially. Different useful characters are introduced in such varieties.

(ii) Some naturally occurring varieties cannot withstand environmental stress like frequently changing temperatures, wet and dry famines, changing climates, etc. However, GM crops can grow in any of these adverse conditions.

(iii) As GM crops are resistant to insect pests, pathogens, chemical weedicides, etc., the use of harmful chemicals like pesticides can be avoided.

(iv) Due to the use of seeds from GM crops, there is an improvement in nutritive value and a decrease in crop losses.

7. Which two main techniques are used in biotechnology? Why?

Ans:

(i) The two main techniques used in biotechnology are genetic engineering and tissue culture.

(ii) These techniques are used to bring about improvements in living organisms through artificial genetic changes and hybridization for the welfare of human beings.

(iii) Its uses are in the production of cash crops, the improvement of varieties of cash crops, the early diagnosis of congenital diseases, organ transplants, cancer research, and the production of artificial skin, cartilage, etc. in laboratories.

8. Discuss ‘Agritourism’ in the class and write a project on an agro-tourism centre nearby. Present it in the class in groups.

Ans: 

(i) In agritourism, plantlets of flowering, medicinal, ornamental, vegetable, and fruit trees are produced on a large scale by the tissue culture technique.

(ii) By growing some of the plants fully, an agritourism centre can be developed.

(iii) If sufficient land is available, the emerging field of agritourism would be a good business.

(iv) An agritourism centre consists of the following:

(a) Mango, chikoo (sapota), guava, coconut, custard apple, and some other regional fruit trees

(b) Shade-giving local or exotic attractive plants

(c) Ornamental and flowering plants

(d) Butterfly garden

(e) A medicinal plant garden

(f) Organic vegetables and fruits

(v) People visit places with such attractions in large numbers.

(vi) Selling plantlets, seedlings, fruits, and vegetables at such places can be quite profitable.

9. Define the term tissue and explain the concept of tissue culture.

Ans: A group of cells having the same origin, structure, and function is called a tissue. Concept of tissue culture:

(i) The ex vivo growth of cells or tissues in an aseptic and nutrient-rich medium is called tissue culture.

(ii) Nowadays, a complete organism can be developed from a single cell or from tissue with the help of the tissue culture technique.

(iii) A liquid, solid, or gel-like medium prepared from agar, which supplies nutrients and energy necessary for tissue culture, is used in this technique.

(iv) Tissue culture can be used to grow plants on a large scale that bear flowers and fruits of excellent quality in shorter durations and are disease-free.

(v) The various processes involved in tissue culture are: