Class 9 MAHARASHTRA STATE TEXTBOOK BUREAU Solutions Science Chapter 17 - Introduction to Biotechnology

a. Ciliated columnar epithelium is present in respiratory tract.

b. Cuboidal epithelium is present in kidneys.

c. Aerenchyma helps the plant to float in water.

d. Striated muscles are also called voluntary muscles.

e. Chlorenchyma is present in permanent tissue.

a. Meristematic tissue. It has the ability to divide whereas the others have lost the ability to divide.

b. Epidermis. It is a plant tissue whereas the others are animal tissues.

c. Cardiac muscle. It is a muscular tissue whereas the others are connective tissues.

a. Squamous epithelium

b. Tendon

c. Apical meristem

d. Lateral meristem

Differences between simple tissue and complex tissues in plants:

Meristematic tissue

• Meristematic tissue is present in specific parts of a plant where growth takes place.
• The cells are compactly packed together and are highly active.
• Cells of meristematic tissue contain thick cytoplasm, a conspicuous nucleus and a thin cell wall.
• Vacuoles are usually absent in these cells.
• The main function of meristematic tissue is to bring about plant growth.
• According to the location, meristematic tissues are of three types:

o Apical meristem

o Intercalary meristem

o Lateral meristem

Xylem

• Xylem is a complex permanent tissue in plants.
• It consists of thick-walled dead cells.
• The type of cells in xylem include the tracheids, vessels, xylem fibres (dead cells) and xylem parenchyma (living cells).
• The xylem consists of interconnected tubes which conduct water and minerals only in upward direction.

Striated muscles

• The cells of striated muscles are long, cylindrical, and multinucleate without branches.
• These muscle cells show alternate dark and light bands.
• As they are attached to the bones, they are also called skeletal muscles.
• They move as per our will, hence they are called voluntary muscles.
• Striated muscles bring about movements of arms and legs, and activities like running, speaking, dancing, etc.

Agro-complementary business

• The businesses that are complementary to agriculture and generate supplementary income for the farmers are called agro-complementary businesses.
• These include animal husbandry, sericulture, poultry farming, apiculture and pisciculture.
• Animal husbandry: It is practiced 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 for pulling heavy loads.
• Poultry farming: It is the rearing of egg and meat yielding chickens. Chickens raised for eggs are called layers while those raised for meat are called broilers.
• Sericulture: It is the rearing of silkworms (moths) for silk production. The silk fibres obtained are processed, reeled and then woven into fabric.

Genetic engineering

• Genetic engineering is the deliberate modification of the characteristics of an organism by manipulating its genetic material.
• An organism that is generated through genetic engineering is called a genetically modified organism (GMO).
• Genetic engineering is applied in many fields like research, agriculture, industrial biotechnology and medicine.
• In agriculture, genetic engineering is used in the production of cash crops, improvement in varieties of cash crops and enhancing the ability of plants to withstand environmental stresses.
• In medicine, genetic engineering is used for vaccine production, early diagnosis of congenital diseases, organ transplant, cancer research, production of artificial skin, and cartilage in laboratories.

Sericulture

• Sericulture is the rearing of silkworms (moths) for production of silk.
• Bombyx mori is the most commonly used variety of silkworm for the purpose of sericulture.
• The life cycle of a silkworm consist of four stages namely egg, larva, pupa and adult.
• Thousands of eggs deposited by the female moths are incubated artificially to shorten the incubation period.
• Larvae hatching out of eggs are released on mulberry plants. The larvae are nourished by feeding on mulberry leaves.
• After feeding for 3-4 days, larvae move to branches of mulberry plant.
• The silk thread is formed from the secretion of their salivary glands.
• Larvae spin this thread around themselves to form a cocoon. The cocoon may be spherical in nature.
• Ten days before the pupa turns into an adult, all the cocoons are transferred into boiling water.
• Due to boiling water, the pupa dies in the cocoon and silk fibres become loose.
• These fibres are unwound, processed and reeled.
• Various kinds of fabrics are woven from silk threads.

The techniques of bringing about improvements in living organisms by artificial genetic changes and hybridization for the welfare of human beings, are together called biotechnology.

Impact of biotechnology on agricultural management:

• Genetically modified crops (GM crops) are being produced by introducing changes in DNA of natural crops.
• Thus, new varieties are produced artificially which possess certain useful characters than the natural varieties.
• Some naturally occurring varieties cannot withstand environmental stress like frequently changing temperature, wet and dry famines and changing climates. However, GM crops can grow in any such adverse conditions.
• The use of harmful chemicals like pesticides can be avoided as GM crops are resistant to insect pests, pathogens, and chemical weedicides.
• Due to use of seeds of GM crops, there is an improvement in the nutritive value and decrease in loss of crops.

The two main techniques used in biotechnology are -

1. Genetic engineering

2. Tissue culture

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

These techniques are useful in the production of cash crops, improvement in the varieties of cash crops, early diagnosis of congenital diseases, organ transplant, cancer research, production of artificial skin and cartilage in laboratories.

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

An agritourism centre can be developed by growing some of the plants fully. If sufficient land is available, the emerging field of agritourism would be a good business.

An agritourism centre consists of 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) Medicinal plant garden. (f) Organic vegetables and fruits.

People visit places with such attraction in large numbers. Selling plantlets or seedlings, fruits, vegetables at such places can be quite profitable.

Tissue

A group of cells having the same origin, same structure and same function constitute a tissue.

Tissue culture

• Ex vivo growth of cells or tissues in an aseptic and nutrient-rich medium is called tissue culture.
• Now-a-days, an entire organism can be developed from a single cell or from tissue with the help of tissue culture technique.

• A liquid, solid or gel-like medium prepared from agar is used in this technique. It supplies nutrients and energy necessary for tissue culture.
• Tissue culture can be used to grow plants on a large scale and in a shorter duration. Such plants will bear flowers, fruits of excellent quality and will be disease-free.

The term livestock refers to animals reared for profit or for domestic use. Sheep provides us with wool, skin, meat and milk. Therefore, rearing of sheep is a livestock.