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 Bihar Board 12th Biology Important Questions Short Answer Type Part 5

Bihar Board 12th Biology Important Questions Short Answer Type Part 5

Question 1.
What was Darwin view on his visit to Galapagos Islands.
Answer:
In Galapagos Islands, Darwin observed amazing diversity of creatures. A small black bird called finches amazed him. He realised that there were many varieties of finches within the same island. All the varieties, he conjectured, evolved on the island itself. From the original seed eating features, many other forms with altered beaks arose, enabling then to become insectivorous and vegetarian finches. This process of revolution is regarded as adaptive radiation.

Question 2.
What was the contribution of Lamarch for the evolution of life forms?
Answer:
Lamarch a French naturalist has said that evolution of life forms had occurred but driven by use and disuse of organs. For example, giraffes who in an attempt to forage leaves on tall trees had to adopt by elongation of their necks. As time passed, this acquired character of elongated neck passed to succeeding generations. Giraffes slowly, over the years, came to acquire long necks!

Question 3.
Define cleaning. What are its advantages?
Answer:
The production of one individual organism or a group of organisms of identical genotype or cells that have been derived from a single parental organism or cell. Cloning is of two types: gene cloning and organism cloning.

Cloning is very beneficial in DNA fingerprinting. DNA-probe, gene therapy and genetic engineering.

Question 4.
What is therapeutic cloning? Write its some uses?
Answer:
Therapeutic cloning is used to repair damaged tissues and diseased organs. Its uses are:

• In the production of cloned embryos and harvesting of their stem cells to repair damaged or defective tissue in the DNA donor.
• Human embryonic cells can be transformed into insulin producing cells
• Mature nerve cells can be created from human embryonic stem cells
• Human embryos can be created from stem cells through cloning.

Question 5.
What is genetic engineering?
Answer:
Genetic engineering is the science which deals with the synthesis of artificial genes, repair of genes, combining of genes from two organisms (recombinant DNA) and manipulation of the artificial genes for improvement of living beings.

Question 6.
What is difference between the nucleoside and nucleotides?
Answer:
Nucleoside – A purine or pyrimidine base that is attached to a deoxyribose sugar.
Nucleotide – A phosphoric ester of nucleoside.

Question 7.
How antibiotics are produced? What are their properties?
Answer:
Antibiotics are produced by lichens, fungi, actinomycetes and eubacteria. According to their effect they may be specific antibiotics or broad spectrum antibiotics. They have following properties:

• The antibiotic should be able to destroy all the strains of the parasite,
• It should not produce any allergic reactions or toxic to the host,
• The antibiotic should not be harmful to natural and useful microbial flora of the host.
• Is should have broad spectrum application beside being specific for a particular pathogen.
• Antibiotics kill the pathogen by breaking a vital link in the metabolism of the pathogen.

Question 8.
Which steps are involved in genetic engineering?
Answer:
Genetic engineering process has several steps:

• Gene isolation – The desired gene is cut with restriction enzymes and joined by ligases to host DNA.
• Synthesis of gene – The nucleotides are synthesized chemically.
• Transformation – The DNA is incorporated into genome of a cell.
• Transduction – The DNA is carried from a donor bacterium to a recipient bacterium with the help of bacteriophages. It results in changing the recipient’s genotype.
• Gene cloning – It is a technique for producing new combination of genetic material in bacterial cells. The DNA is inserted in the vector, where it produces copies of itself.

Question 9.
Define biotechnology.
Answer:
According to EFB (European Federation of Biotechnology) “Biotechnology is the integrated use of biochemistry, microbiology and engineering sciences in order to achieve technological application of the capabilities of micro-organisms, cultured tissues/cells and parts their of.”

Question 10.
What are stem cells? What is stem cell therapy?
Answer:
The cells of young embryo (approx 40) are called stem cells. They are capable of transforming into any of the 220 cell types human body, they are pluripotent. These are used in therapy called stem cell therapy. For example, if injected into various organs, stem cells can rejuvenate them like stem cells transformed to islet cells can cure diabetes, stem cells that form nerve cells can cure spinal cord injuries. Alzheimer etc.

Question 11.
What are plasmids, why they are suitable for use as a vehicle DNA?
Answer:
Plasmids are circular, double stranded DNA molecules which occurs as extrachromosomal material and can replicate independently. They serve as vectors or cloning vehicles in prokaryotes like bacteria. The ideal plasmid vector has three properties for suitable use as cloning vector:

• low molecular weight, it makes handling easy
• ability to confer readily with selectable phenotypic traits on host cells
• single sites for a large number of restriction enzymes.

Question 12.
What is antisense nucleic acid?
Answer:
This is single stranle stranded molecule of DNA or RNA, which base pairs with mRNA molecules and block its translation. This process of inactivation of specific in RNA is used against viral replication and transformation on normal cells into cancerous cells and this can stop the further spread of the disease.

Question 13.
Diagramatically show the construction of a chemeric plasmid.
Answer:
Chemeric or recombinant plasmids have an additional foreign fragment of DNA. It can be shown like this:

Question 14.
What are cDNA libraries? How they are made?
Answer:
A complete library of genome fragments is a set of independent clones, that contains the entire genome among the recombinant DNA molecules. Genomic libraries are also called gene banks. Construction of cDNA library involves following steps:

• the generation of DNA segments
• introduction of DNA fragments into a cloning vector like plasmid, cosmid or virus
• introduction of cloned DNA into a bacterium like E. Coli.

Question 15.
What are second generation vaccines?
Answer:
With the help of genetic engineering vaccines of immense importance are synthesized, called second generation vaccines. These consist of a few antigens present on the surface of the infecting agents rather than the whole inactivated organism (fifst generation vaccine).

The surface antigens are produced in large quantities with the help of recombinant DNA technique. These are injected in safer dozes to healthy individuals for development of immunity. These are more uniform in quality and have less side effects than first generation vaccines. For example, vaccine for Hepatitis-B.

Question 16.
Show diagramaticallv how monoclonal antibodies are produced.
Answer:

Question 17.
What are monoclonal antibodies ? Write down their characteristics.
Answer:
In 1970, Georges Kohler and Cesar Milstein developed the technique of producing monoclonal antibodies by fusing normal antibody producing cells with cells from cancerous tumours. Their main characteristics are:

• Monoclonal antibodies are pure and highly specific for specific antigens
• These can be easily cultured outside the body
• These antibodies are more effective and ideal for diagnosis of specific diseases.

Their most effective clinical application is immune suppression for kidney transplantation.

Question 18.
How biotechnology helped in developing herbicide tolerance in plants?
Answer:
Herbicides are chemicals with destroy weeds, but they also have adverse affects on crop plants. With the help of biotechnology, scientists develop such transgenic crops which are resistant to the herbicides, and continue to produce normal yield. This may be achieved by –

• Overproduction of those enzymes which are inactivated by herbicide,
• Mutating the enzymes and making them less sensitive to herbicide,
• Introducing such enzymes which cause detoxification of herbicides. Production of herbicide resistant plants, reduce the use of weeding labour, farmer’s cost and increase yield.

Question 19.
Give a schematic representation of gene therapy.
Answer:

Fig.: An example of gene therapy. A patient of SCID starts developing immune response after receiving a normal functional gene.

Question 20.
What are steroids?
Answer:
Steroids are complex crystallisable lipids of high molecular might, with a core structure of one 5-carbon ring and three 6-carbon rings. They are present in plants as well as in animals. Several micro-organisms like fungi, bacteria, actinomycetes, leasts, protozoan and algae transform naturally available steroids into chemotherapeutically important steroids.

Cholesterol is an important steroid in animals and humans. It acts as starting point for the synthesis of many steroid hormones like male sex hormonetestosterone, and female sex hormones-progesterone and oestrogen.

Question 21.
Give some examples of genetically modified organisms.
Answer:

• Bacterium Rhizobium meliloti is used as biofertilizer.
• Bacterium Pseudomonas accumulates heavy metals (Cu, Pb) from environment and fix them into compounds (CuSO4, PbSO4). This is called bioremediation.
• Fungus Fuichoderma helps in biocontrol against pests and plant diseases.
• Fungus Penicillium (Genetically modified) are producing antibiotic penicillium in high amounts, than the natural strains.
• Bacteria are used for the synthesis of various enzymes like cellulose and vitamins like human growth hormone.
• Bacillus thuringiensisis used as insecticide.

Question 22.
Give example to support how genetic engineering can help in improving the process of photosynthesis.
Answer:
Photosynthesis can be improved by controlling the enzymes which play important role during the process of photosynthesis. For example, RUBISCO enzyme.
Ribulose 1, 5-bisphosphate (RUBISCO) is an important enzyme of photosynthesis which can act both on CO2 and O2. Under certain condition, in light, the enzyme RUBISCO oxygenates Ribulose bisphosphate and inhibits carboxylation as a result of which 25% of the fixed CO2 is photorespired as CO2.

It is now possible to isolate the RUBISCO gene, modify it accordingly and reinsert into plants to minimise the loss due to photorespiration. One such gene controlling RUBISCO enzyme has been transferred from pea plant to tobacco plant to increase photosynthetic process and high leaf yield.

Question 23.
What is biopatent? What are the flaws of US patent law?
Answer:
Biopatent is government protection to an inventor of a biological material, securing to him for a specific time, (usually 20 years) the exclusive right to manufacture, use and sell its products.

US patent law does not recognise technologies and methods which are used in other countries as ‘prior art’, if this knowledge is new for US.

Question 24.
What is biopiracy?
Answer:
Biopiracy is the theft or robbery of biological and genetic resources indigenous to a country. The process of biopiracy involves collection of biological samples without permission and commercial scale production of the product for benefits. Biopiracy is widespread in developing countries which have diverse ecosystems and posses abundant bio resources.

Some multinational corporations benefit greatly from biopiracy activities. These do not pay any financial compensation to the countries where biological material originated. It robs us of our right to utilize our own resources.

Question 25.
(i) Give the scientific name of the soil bacterium which produces crystal (Cry) proteins.
(ii) How are these proteins useful in agriculture?
(iii) What do the differently written terms ‘Cry’ and ‘cry’ represent respectively?
Answer:
(i) Soil bacterium – Bacillus thuringiensis produces crystal (Cry) proteins.
(ii) This protein acts as a toxin for insects. If gene for ‘Cry’ protein is incorporated into crop plants they will develop resistant to the insects and pests.
(iii) ‘Cry’ is used for Cry protein and ‘cry’ is used to denote gene which encodes for ‘Cry’ protein.

Question 26.
Enlist some pharmaceutical products, produced by genetic engineering techniques.
Answer:
(i) Hormones – Mammalian hormones are the first products prepared in bacteria by recombinant DNA technology, human insulin and human growth hormone are some examples.

(ii) Immunomoduiations – (a) These are antisense nucleic acid, which bind to the mRNA of viruses and inactivate them and (b) genetically engineered proteins which block the surface receptors on cell membrance so that the pathogenic antigens can’t bind the membranes, (c) vaccines are produced which are pure and more effective.

(iii) Interferons – Interferons are proteins produced by infected cells to limit cell to cell spread of viruses in the body. Interferons can be produced in large amounts by recombinant DNA technology.

Question 27.
Define a patent.
Answer:
A patent is an official document giving the holder of the patent, sole rights to make, use or sell an invention and prevent others from limitating it. A patent can be granted for an invention, an improvement in an invention, process of generating a product or testing and for a concept or design.

Question 28.
Write two symptoms of AIDS.
Answer:
The two symptoms of AIDS are as follows:

1. The weight of body decreases gradually due to AIDS
2. The body is always maintaining fever.

Question 29.
Write a short notes on:
(a) Production of human growth hormone by E. Coli
(b) Animals as organ donors for humans
(c) Plant Variety Protection and Farmer’s Right Act.
Answer:
(a) Production of human growth hormone by E. Coli – Human growth hormone (HGH) is very useful to children born with hypopituitarism which is a form of dwarfism caused by under secretion of HGH by anterior pituitary gland. It also helps in heating of injuries. The gene for HGM M is introduced in the plasmid of bacterium E. Coli. This recombinant E. Coli bacterium secretes Human growth hormone which is used for treating hypopituitarism.

(b) Animals as organ donors for humans – Successful operations were carried out so far, to donate organs from live person or deceased person. These include organs like heart, intestine, kidneys, lungs, pancreas, grafts like bones, corneas, heart valves, skin grafts, tendon etc. Most of times all the donor were human beings. Scientists are working out ways to develop some healthy tissues inside animals which may serve the same function if implanted in human body, but there are risks of severe allergies and autoimmune response.

(c) Plant Variety Protection and Farmer’s Right Act – Grants plant breeders the right on new varieties of seeds. The Farmer’s Rights Act has granted the farmers the right to save, use, sow, re-sow, exchange, share or sell his farm product including seeds.

Question 30.
Explain the following terms in one or two sentences intellectual property rights, humulin and bio-fortified foods.
Answer:
Intellectual property rights – Intellectual Property Rights (IPRs) are rights to make, use and sell a new product or technology for a period of 20 years to the inventor. These are granted in the form of patents, trademarks and copyrights.

Humulin – Humulin is the commercial name given to human insulin by an American firm Eli Lily. These insulins are manufactured by genetic engineering using fermentation of appropriate recombinant E. Coli clones.

Bio-fortified foods – With the help of genetic engineering techniques biotechnologists, have developed plants which are rich in nutritional content. These are potato with increased starch content upto 20 – 40%, Tomato with delayed ripening, golden rice which is rich in vitamin A.

Question 31.
Explain why scientists have failed to produce vaccines against AIDS.
Answer:
AIDS spread through HIV virus. It is a retrovirus with RNA as genome. Chances of mutation are very high in RNA. The virus every time mutates in its reverse transcription and replication cycle. Most HIV particles produced in an infected person differ in surface receptors at least slightly from those on the original infecting virus.

Question 32.
What is cancer? What are three main types of cancer?
Answer:
Cancer is characterized by uncontrolled growth and division of certain body tissues thus forming a tumour. Such cells are called neoplastic cells. Cancer cells do not undergo differentiation and have high invasiveness. Depending on the basis of location cancerous tumours are of three types

1. Carcinomas – Cancer which are located in epithelial tissues e.g. breast, stomach, lung, skin and pancreas cancer.
2. Sarcomas – Cancer of connective tissue and muscular tissue derived from mesoderm e.g. bone, lymph nodes and muscle cancer.
3. Leukaemia or Blood cancers – It affects children below 15 years. WBC count in blood increases due to increased formation of WBCs in bone marrow, which decreases erythropoiesis and RBCs count.

Question 33.
What is meant by reservoirs of infection.
Answer:
Reservoirs of infection are those sites which are occupied by pathogens, when they are not inside the human body. There are different for different pathogens. They are of following type:

• Carriers or vectors – Those living organisms which spread the pathogens form an infected person to healthy person. Themselves they do not suffer from the disease, e.g. for plasmodium (pathogen) the carrier host is female Anopheles mosquito.
• Soil is the reservoir of infection of Clostridium tetani (tetanus bacteria).
• Air is reservoir of bacterial cysts of tuberculosis and diphtheria and many others.
• Food and water – They serve reservoir for cholera, typhoid, polio, Entamoeba histolytica etc.

Question 34.
Write down the effects of Nicotine on human body?
Answer:
Nicotine stimulates passage of nerve impulses, causes muscles to relax and causes the release of adrenalin, increases both blood pressure and rate of heart beat. The increased blood pressure caused by smoking leads to increased risk of heart diseases.

Question 35.
Briefly write the functions of macrophages.
Answer:
Macrophages have following functions:

• Defence – Wandering macrophages dispose of microbes in the connective tissue. They are known as histiocytes. Fixed macrophages destroy microbes in the blood and lymph.
• Scavenging – Macrophages also dispose of dead tissue cells and noncellular foreign matter.
• Antigen display – Macrophages carry the antigens on their surface and display them to lymphocytes.
• Many macrophages may fuse to form a large multinucleated giant cell to capture a big size foreign body.

Question 36.
Explain why secondary immune response is very quick and intense?
Answer:
Secondary immune response is very quick and intense because the memory B-cells persisting from the primary immune reaction quickly form antibodies to deal with microbes.

Question 37.
Why skin is called a self-disinfecting organ?
Answer:
Skin is called a self-disinfecting organ because sweat and sebum, which are secreted by sudoriferous glands and sebaceous glands contain lactic acid and fatty acids which check microbial growth on the skin. Sweat also contains lysozyme which kills bacteria.

Question 38.
What is passive immunity?
Answer:
Immunity is called passive when antibodies produced in other organism are injected into a person who already has a potential antigen in his body. For example passive immunity is developed to counteract snake venom and rabies.

Question 39.
In case of infectious disease, having fever is beneficial for the body?
Answer:
In case of severe infection, body temperature rises, causing fever. Mild fever strengthens the defense mechanism by activating the phagocytes and inhibiting the growth of the microbes.

Question 40.
What are interferons?
Answer:
Interferons are antiviral proteins secreted by virus infected cells. It is released from the infected cells and makes the nearby uninfected cells more resistant to the viral infection.

Question 41.
With examples, define distilled and undistilled alcohols.
Answer:
Alcohol produced by mere fermentation of raw material is called undistilled alcohol, e.g. beer, champagne, Alcohol formed by distilling the fermented product of raw material is called distilled alcohol, e.g. whisky, brandy etc.

Question 42.
Write a note on cirrhosis.
Answer:
Liver converts alcohol into fat that is stored in liver cells. Excess fat reduces formation of glycogen, enzymes and structural proteins. The fatty liver then hardens and dries up as its cells are replaced by fibrous tissue. The degeneration of liver is known as cirrhosis.

Question 43.
What are intervarietal and interspecific hybridisation?
Answer:
Intervarietal hybridisation is a cross between the two varieties of the same species whereas interspecific hybridisation is a cross between the different species of the same genus.

Question 44.
Name the two main classes of general drugs. Give their source and one example of each.
Answer:

1. Natural drugs obtained from plants, e.g. quinine and morphine, from animals, e.g. heparin and liver extract, and microorganisms, e.g. penicillin and streptomycin.
2. Synthetic drugs which are manufactured in the laboratory, e.g. aspirin, chloroquine etc.

Question 45.
What are endogenous and exogenous chemical agents of disease?
Answer:
Endogenous chemical agents are those which are formed in the body itself. These may be hormones, urea etc. Exogenous chemical agents are those which enter the body from environment through water, air, food etc. for example fumes, spores etc.

Question 46.
How infection is different from infestation?
Answer:
Infection is the entry of a pathogen inside the host’s body, whereas infectation is the presence of pathogens, generally arthropods on the body Surface or on the clothes, e.g. louse infestation.

Question 47.
What are the aims of plant breeding?
Answer:
Plant breeding is mainly concerned with the production of plants having desired characters such as high yield, better adaptation, resistance to diseases and pests etc.