Solution-Class 9-Science-Chapter-17-Introduction to Biotechnology-Maharashtra Board

a. Ciliated 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. Chloroplast is present in simple permanent tissue.

Meristematic tissue is the odd one out because xylem and phloem are types of permanent tissues.

Epidermis is the odd one out because all the other are Permanent tissues. Epidermis is an outer layer of cells found in plants.

Cardiac muscle is the odd one out because rest of the three are connective tissues while cardiac muscle is a type of muscular tissue.

squamous epithelium

Tendon-Connective tissue

Apical meristem

Lateral meristem

Meristematic tissues: Meristematic tissues are the cells or group of cells that have the ability to divide. These cells divide continuously and thus helps in increasing the length and thickness of the plant.

• The main function of meristematic cells is bringing out growth.
• There is thick cytoplasm, a conspicuous nucleus and a thin cell wall which are compactly packed together. These are characteristics of meristematic tissues.
• The meristematic cells are highly active and they do not have vacuoles in them.

Depending upon the position, meristematic tissues can be classified as:

• Apical Meristem: It is present at the growing tips of stem and roots. It increases the length of the plant body. The apical meristems produce three kinds of primary meristems i.e., protoderm, ground meristem and procambium.
• Intercalary Meristem: It is present at the base of the leaves. This meristem helps in the elongation of internodes.
• Lateral Meristem: It is present at the lateral regions of the stems and roots which bring about an increase in the width of the plant body. These are of two types: cork cambium and vascular cambium.

• Xylem is a part of conducting tissue of the higher plants.
• Xylem consists of thick-walled dead cells.
• Xylem has structure like interconnected tubes.
• Function of the xylem is to conduct Water and minerals only in upward direction.

There are two kinds of cells in the Xylem, viz. dead cells and living cells.

• Tracheids: It is a non-living, elongated cell with tapering ends. The wall is highly thickened with lignin, except at certain circular spots known as pits.
• Vessel: It is a non-living cell with lignified walls. Tracheids and vessels are the main conducting elements in the xylem.
• Xylem fibre: It is a non-living, thick walled cell which provides mechanical support.
• Xylem parenchyma: It consists of living cell and performs the function of storage.

Striated muscles: Striated muscles are also known as skeletal muscle fibres.

• Skeletal muscle fibres are striated and are bundled together in a parallel manner by a sheath of tough connective tissues.
• Striated muscle cells are long and cylindrical in shape.
• They are multinucleate and are without any branches.
• These are attached to the skeletal bones and are voluntary in nature (because their actions are directly under the control of person’s will). 
• These muscles bring about movements of arms and legs such as running, walking etc. They help in turning, speaking, too.

Agro-complementary business: It includes animal husbandry, poultry farming and sericulture.

• The complementary good or services that are used in conjunction with agriculture are referred to as agro-complementary business. 
• Agro complementary business are mainly carried out to produce high yielding breed, desirable quality and for economic benefit.
• Animal husbandry is practiced for milk production and the cattle is used for farming, poultry farming is done for the rearing of eggs and meat and sericulture is done for rearing of silk.
• This gives supplementary income. Such agro-complementary businesses can give financial benefits and help the farmers to become more self sustaining.

Genetic engineering: Genetic engineering which is also known as gene manipulation/recombinant DNA technology involves the modification of the genetic information of living organisms by manipulation of

• Genetic engineering is the important technique in the biotechnology. By this technique, the sequence of nitrogenous bases can be altered.
• This helps us to form a species with desired characters.
• In addition to the natural characteristics, the plants and animals having newer and useful characteristics are formulated by genetic engineering.

There are various applications of genetic engineering:

• It is used in the synthesis human insulin and interferons.
• Producing enzymes, proteins, vaccines and antibiotics by bioprocess technology
• Developing pest-resistant and disease-resistant crops
• Identifying and correcting genetic defects by gene therapy
• Forensic application, in the identification of criminals using restriction fragment length polymorphism (RFLP)

 Sericulture: The rearing of silkworms to obtain silk fibre is known as sericulture. Silk fibre is obtained from Bombyx mori or silk moth.

The methodology of sericulture includes five steps:

1. Collection of eggs ­: The ripened cocoons are collected and adult moths are allowed to come out of them and mate. The females are then collected and kept in a bag with mouth sealed and within some time, they die after laying their eggs, which are recovered for further process.
2. Incubation of eggs : The obtained eggs are spread evenly on tray and kept in incubator at 65°F. The temperature is slowly increased day after day and eggs hatch at 77°F. Larvae are recovered from the incubator.
3. Rearing of larvae Larvae are reared in special rooms maintained at 77°F. They feed on mulberry leaves and become double their size in 4-5 days. During this 40 days larval period, 4 cycles of sleep followed by moulting is encountered.
4. Recovery of silk from cocoon : Before pupa turns into an adult, all the cocoons transferred into boiling water. This is done 10 days before the cocoon opens and the adult moth can out. Because of boiling water, the pupa dies in cocoon and silk fibres become loose
5. Reeling and spinning : The process of removing the silk thread from the killed cocoon is called reeling. The silk so obtained is the raw silk, which is boiled and purified by acids to bring lustre.

For the benefit of human beings, biotechnological techniques are carried out. These methods are for bringing about improvements in living organisms by artificial genetic changes and by hybridization. All such techniques are together called biotechnology.

• Biotechnology includes the techniques of genetic engineering and tissue culture.
• Natural characters of some species may not have all useful features. Some of the characters may be deleterious. In order to avoid such varieties, GMO or Genetically Modified Organisms are created. For this purpose, the DNA is changed in the crops. The modified crops then possess required features.

Following changes have occurred in the crops due to biotechnology :

• The varieties that can withstand the changes in the environment can be created. E.g., constantly changing temperature, dry and wet droughts, climate change and some similar stressor-resistant varieties are produced through genetic engineering.
• GM crops are resistant to insect pests, pathogens, chemical weedicides, etc., due to their changed genome. This reduces the use and the cost of chemical pesticides which are harmful.
• Due to use of seeds of GM crops, there is improvement in nutritive value of crops. Therefore now, seeds of a better quality of crops are being produced.
• There is also a decrease in loss of crops. Subsequently there is increase in the cultivable land and agriculture.
• Some insect resistant crops such as Bt Cotton have been produced which is widely used in Maharashtra.

The two main techniques which are used in biotechnology are tissue culture and genetic engineering.
In genetic engineering nucleotide sequence is changed and thereby genes are manipulated. The modified organisms are then bred and from such crosses more such organisms are created.

• ‘Ex vivo growth of cells or tissues in an aseptic and nutrient-rich medium’ is called tissue culture.
• Nowadays, a complete organism can be developed from a single cell by the tissue culture methods.
• By both genetic engineering and tissue culture methods, cash crop production is increased.
• Environmental change-resistance varieties are produced which can sustain the drought conditions.
• In the field of medicines, vaccine production, early diagnosis of congenital diseases, organ transplant, cancer research, production of artificial skin, cartilage, etc. can be done in laboratories.

Project activity :. Kindly do it yourself.

Groups of cells performing the same function are known as tissues. 

Plant tissue culture is the production of new plants from small amounts of plant tissue under carefully controlled laboratory conditions. In this method, some plant tissues are taken under sterile conditions and are kept in test tubes containing culture medium, which allows these cells to grow fast and form an unorganised mass of cells called callus. This callus is transferred into another medium containing proper growth hormones for differentiation and organ formation. As a result, small plantlets are formed in the test tubes. These can be later placed in soil where they can grow into mature plants. This technique is called micro-propagation.

Tissue culture has various applications like:

• It is used to produce disease resistant and high yielding varieties of plants.
• Tissue culture is helpful to produce new varieties of plants by fusing two different cells through a technique called germplasm hybridisation and then growing the fused cells through tissue culture. For example: Pomato.
• Tissue culture along with recombinant DNA technology has made it possible to transfer nitrogen fixing genes from bacteria into plants. This has helped these plants to fix atmospheric nitrogen.
• It helps to produce large number of plants in short duration of time and in limited space.
• It has made it possible to preserve characteristics of the parent plants.

Rearing of sheeps refers to farming of sheeps for various purposes. It is among the traditional business and occupations of the people of some countries around the world. In India, the cattle are reared for milk and also for agricultural work.

• Cows, buffaloes and bulls are mainly used for such purposes.
• Goat and sheep are also used in animal husbandry practices.
• These animals are used for obtained meat and wool.
• Meat industry uses goat and sheep meat to a large extent in India.
• Wool of sheep has great demand in markets.
• The sheep and goat are also used to obtain manure.
• They are made to sit in the farms. Their droppings make farms naturally fertile due to this high nitrogen rich excreta.
• One need not spend lots of money for the maintenance of the sheep.
• They have better resistance to the diseases.
• Being small in size they are easily manageable by the lady of the house.
• Thus, rearing a sheep is like maintaining a livestock.