BIOLOGY 3 Marks Question

1. Agro-chemical based agriculture.
2. Organic agriculture.
3. Genetically engineered crop-based agriculture.

1. Insulin being a hormone is produced in very little amounts in the body. Hence, a large number of animals need to be sacrificed for obtaining small quantities of insulin. This makes the cost of insulin very high, demand being manyfold higher than supply.
2. Slaughtering of animal is also not ethical.
3. There is potential of immune response in humans against the administered insulin which is derived from animals.
4. There is possibility of slaughtered animals being infested with some infectious micro organism which may contaminate insulin.

• Tobacco plant, roots are infected.
• Agrobacterium acts as the vector for the introduction of nematode-specific genes into the host plant.
• The DNA is introduced such that it produces both sense and anti-sence RNA in the host plant.
• Since these two RNAs are complementary to each other, they form a dsRNA, which initiates RNA interference.

1. Vaccine: Inactivated/weakened/pathogens injected into the body which produces special antibodies/generate immune response.
   Example: Hepatitis B.
2. DTP Vaccination: Diphtheria, tetanus, pertussis.

1. Providing the best catalyst in the form of improved organism, usually a microbe or pure enzyme.
2. Creating optimal conditions through engineering for a catalyst to act.
3. Downstream processing technologies to purify the protein or other compounds.

The reasons are:

1. To have some ethical standards to evaluate the morality of human activities that might help or harm living organisms.
2. Genetic modifications of organisms may have unpredictable results when such organisms are introduced into the ecosystem; hence a regulation is necessary.

Its responsibilities are:

1. To make decisions regarding the validity of GM research.
2. To check the safety of introducing GM-organisms for public services.

(It produces insecticidal Cry protein). Spores of this bacterium kill larvae of certain insects.

1. To take up the (hydrophilic) DNA from the external medium.
2. Divalent calcium ions increase the efficiency of DNA entering the cell through pores in the cell wall.

2. To introduce alien DNA into the plant cell by bombarding them with high-velocity microparticles. (gold or tungsten coated with DNA)

1. Enzyme-linked immunosorbent assay.
2. It is based on the principle of antigen-antibody interaction.
3. The infection can be detected by.
4. The presence of antigens.
5. The antibodies produced against the pathogen.

1. PCR helps in early detection of disease or Pathogen. The presence of a pathogen (bacteria, viruses, etc) is suspected only when the pathogen has produced a disease sympton. But by that time, the number of pathogens is already very high in the body. However, PCR can detect even very low concentrations of these pathogens.
2. This technique can be used routinely to detect HIV in suspected AIDS patients.
3. It is also used to detect mutations in genes in suspected cancer patients and is also a powerful technique to identify several genetic disorders.

1. ADA (Adenosine Deaminase) deficiency is a form of SCID (severe combined immunodeficiency) a type of disorder that affects the immune system. The disease is caused by a mutation in a gene on chromosome 20. The gene codes for the enzyme adenosine deaminase (ADA). Without this enzyme, the body is unable to break down a toxic substance called deoxyadenosine. The toxin builds up and destroys infection-fighting immune cells called T and B lymphocytes.
2. Girl A was given Enzyme replacement therapy in which lymphocytes isolated from patient’s blood are cultured in-vitro. Functional ADA cDNA are then introduced into the cultured lymphocytes. These lymphocytes are returned back to the patient’s body.

Lymphocytes are not immortal. Therefore, repeated infusion of genetically engineered lymphocytes is required and hence it is not a permanent treatment and the patient have to revisit periodically in the future.

3. Girl B was treated with gene therapy through the gene isolated from bone marrow cells producing ADA is introduced into cells at early embryonic stages which is a permanent cure so the patient is cured permanently.

1. They help in maintaining species diversity in a community, by reducing the intensity of competition.
2. They keep the prey population under control.
3. It acts as a conduit for energy transfer across trophic levels.

The two factors on which the behaviour of such organisms depend are:

1. Nature of gene transferred.
2. Nature of the host cell.

1. Not chemical in nature.
2. More specific in action against the pest.
3. Safer for environment than chemical pesticides.

A popularly known biopesticide is Bt toxin, which is produced by a bacterium called Bacillus thuringiensis. Bt toxin gene has been cloned from this bacterium and expressed in plants. Bt toxin protein when ingested by the insect, gets converted to its active form due to the alkaline pH of the gut. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually kills the insect.

• ADA is caused due to deletion of gene for adenosine deaminase.
• Lymphocytes from patient’s blood were grown in a culture and functional ADA, cDNA was introduced in these lymphocytes using a retroviral vector.
• The lymphocytes were transferred into the patient’s body. Periodic infusion of such genetically engineered lymphocytes is done because these cells are mortal.
• For permanent cure, gene isolated from the bone marrow cells producing ADA, at early embryonic stage can be a possible cure.

1. Identification of DNA with desirable genes, so that the genetically modified organism has largely desirable genes.
2. Introduction of the DNA with desirable genes, into the host using vector
3. Maintenance of introduced DNA in the host, and transfer of the DNA to its progeny through cloning.

1. Bt cotton (Bacillus thuringiensis) produce proteins that kill son insets like- lepidopterans  (tobacco budworm, army worm). Coleopterans (beetles) and dipterans (flies, mosquitoes).
2. The torin is coded by a gene called cry which are of various types.

Example–proteins encoded by the genes cry LAc and cry II control the cotton bollworms, that of cry I Ab controls corn boror.

3. Bt–tobacco was first cultured to kill hornworm. (Mancluca sexta).

1. Plants/bacteria/fungi/animals whose genes have been altered by manipulation.
2. Tolerance to abiotic stresses/like cold/drought/salt/heat,

Reduced reliance on chemical pesticides/pest resistant crops,

Reduce post-harvest losses,

Increased efficiency of mineral usage by plants,

Enhanced nutritional value,

To create tailor-made plant.

• Cotton plants resistant to insect pests like lepidopterans have been raised through recombinant DNA technology using the genes from the bacterium, Bacillus thuringiensis, which produces Bt-toxins. The genes crylac and cryllAb, encoding the Bt toxins, have been isolated from the bacterium and incorporated into cotton plants.
• The genes code for the insecticidal crystal protein, that is ingested by the insect pest along with the plant parts.
• The inactive toxin is converted into its active form by the alkaline pH of the gut.
• The active form of the toxin binds to the surface of the midgut epithelial cells and creates pores that cause swelling and lysis of the cell and eventually kills the insect pest (lepidopterans).

• Rice is an important food grain, the presence of which goes back thousands of years in Asia’s agricultural history. There is an estimated 200,000 varieties of rice in India alone. The diversity of rice in India is one of the richest in the world. Basmati rice is distinct for its unique aroma and flavour and 27 documented varieties of Basmati are grown in India.
• There is a reference to Basmati in ancient texts, folklore and poetry.

1. Presence of a chromogenic substrate gives blue colour, if the plasmid in the bacteria does not have an insert. (non-recombinants)
2. With the insert do not produce any colour, recombinant colonies.
3. Selection of recombinants due to inactivation of antibiotics, requires simultaneous plating on two plates having different antibiotics/process is more cumbersome.

1. RNA interference (RNAI).
2. Tobacco plant.
3. Meloidegyne incognitia (nematode).
4. Agrobacterium tumefaciens vector.

1. Proinsulin has three polypeptide chains namely A, B and C. The chain C acts as a link between, chain A and chain B. Polypeptide C aligns chain A & B in such way that a disulphide bond is formed between polypeptide A and B. With the formation of disulphide bridge pro-insulin becomes functional. A function insulin has only two polypeptide chain.
2. r-DNA technology or recombinant DNA technology.
3. The polypeptide chain are held together, by disulphide bridges between chain A and B.

• Using conventional methods, early diagnosis is notpossible.
• By the time, the symptoms of the disease appear, the concentration of the pathogen is very high. But by ELISA, the presence of the pathogen can be detected, when its concentration is low and the symptoms have not appeared, hence, early treatment and cure is possible.

1. Golden rice is genetically engineered with Vit A precursor carotenoids.
2. Lack of Vit A causes night blindness.

1. Any gene (from any organism or a synthetic gene) can be used for transfer.
2. Change in genotype is precisely controlled.

• Insulin contains two short polypeptide chains- chain A and chain B linked by disulphide bridges.
• In mammals, insulin is synthesised as a pro-hormone (that needs to be processed to become mature and functional hormone). It contains an extra stretch called C peptide.
• C peptide is absent in mature insulin and is removed during maturation into insulin.
• Earlier, insulin was extracted from pancreas of slaughtered cattle and pigs but some patients began developing allergies.
• Production of insulin by rDNA techniques was achieved by an American company, Eli Lilly, in 1983. It prepared two DNA sequences corresponding to A and B chains of human insulin and introduced them in plasmids of E. coli for production. The A and B chains produced, were separated, extracted and combined, by creating disulfide bonds to form human insulin.

Earlier, insulin was extracted from pancreas of slaughtered cattle and pig. This insulin is not in use as some patients developed allergic reaction to this foreign protein.

Using Agrobacterium vectors, nematode-specific genes were introduced into the host plants. The introduction of DNA was such that it produced both sense and anti sense RNA in the host cells. These two RNA’s being complementary to each other formed a double stranded (dsRNA) that initiated RNAi and thus, silenced specific mRNA of the nematode. The consequence was that the parasite could not survive in a transgenic host expressing specific interfering RNA. The transgenic plant therefore got itself protected from the parasite.

1. Bacillus thuringiensis.
2. These Cry proteins are toxic to certain larvae of insects and thus provide resistance against them. The gene encoding Cry proteins are used in several crop plants (Bt toxin). Such a crop plant is resistant to the particular insect pest.
3. Cry represents crystal protein while cry refers to the gene encoding the Cry protein.

1. Transgenic animals are those animals, which have their DNA manipulated to possess and express one/ more foreign gene(s).
2. Mica.
3. They are produced for the following purposes:

1. Transgenic animals are designed to allow the study of how genes are regulated and how they affect the normal functions of the body and its development, e.g. information has been obtained as to how insulin has a role as growth factor.
2. Transgenic animals that produce useful biological compounds are created by introducing a portion of the DNA that codes for the product, e.g. a-1-antitrypsin is produced for treating emphysema.
3. Transgenic animals are being developed to test the safety of vaccines, e.g. polio vaccine has been tested on transgenic mice.
4. Transgenic animals with more sensitivity to toxic substances are being developed to test the toxicity of drugs

1. (Collection of) methods that allows correction of gene defect that has been diagnosed in a child/embryo/Genes are inserted into a person’s cells and tissues to treat a disease, this involves delivery of a normal gene into the individual/embryo to take over the function of and compensate for non functional/a defective gene.
2. If the desired gene is isolated and introduced into cells at early embryonic stages it can provide a permanant cure.

ADA/Adenosine deaminase deficiency

1. Nematode specific gene introduced into host plant(using Agrobacterium), produced dsRNA, RNAi initiated, specificmRNAof the nematode silenced and parasite dies.
2. Agrobacterium tumifaciens.

1. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis leading to the death of an insect.
2. Bacillus thuringiensis forms protein crystals (Cry) during a particular phase of their growth. These crystals contain a toxic insecticidal protein.

Role of transgenic animal in vaccine safety- transgenic mice are being developed for use in testing the safety of vaccines before they are used on human.

Role of transgenic animal in production of biological products- Transgenic cow, peste is used for the production of human protein-enriched milk, which contained D-actalbamin and was nutritionally more suitable for human babies.

1. Demand for insulin is very high which necessitates slaughtering of a large number of animals.
2. Slaughtering of animals amounts to cruelty against animals.
3. Insulin from animal origin can result in allergic reactions because of body’s tendency to encounter foreign substance.
4. The slaughtered animal can be infected with some dangerous microbes. This can contaminate the insulin.

1. Transgenic E.coli, with gene for human insulin.
2. Transgenic mouse with gene for human growth hormone.

• Fundamental biological processes: Transgenic animals can be used to understand insulin-like growth factors in humans.
  
• Study of Diseases: Many transgenic animals are introduced with genes for certain disease. Then progression and possible cure for such disease can be studied using these animals.
  
• Biological Products: A transgenic cow Rosie could produce protein enriched milk.
  

1. This bacterium produces protein that kills certain insects such as lepidopterans (tobacco budworm and armyworm), coleopterans (beetles) and dipterans (flies and mosquitoes).
2. Bacillus thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein.
3. Bt toxin protein exists as inactive protoxins in bacteria, but once an insect ingests this inactive toxin, it is converted into an active form due to the alkaline pH of the gut, which solubilises the crystals.
4. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis leading to death of insect.
5. Specific Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into several crop plants.
6. Most Bt toxins are insect-group specific. The toxin is coded by a gene named cry. For example, the proteins encoded by the genes cry IAc and cry IAD control the cotton bollworms and cry IAb controls corn borer.

• GM crops are more tolerant to various stresses.
• GM crops reduce the reliance on pesticides and synthetic fertilizers.
• GM crops can enhance nutrient value of a particular food.

1. The agro-chemicals used in agriculture are too costly.
2. Excess use of chemicals in field adversely affects our environment by causing pollution. GMO's are beneficial in many ways.

1. Tolerance against abiotic stresses, such as cold, drought, salt, heat.
2. Reduce dependence on chemical pesticides.
3. Reduce post-harvest losses.
4. Increase efficiency of mineral usage by plants.

1. In first step of gene therapy, lymphocytes from the blood of the patient are grown in a culture outside the body.
2. A functional ADA cDNA (using a retroviral vector) is then introduced into these lymphocytes which are subsequently returned to the patient.
3. As these cells are not immortal, the Patient requires periodic infusion of such genetically engineered lymphocytes. But if the gene isolated fiom marrow cells producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure.

Therapy is not completely curative, periodic infusion of enzyme required.

1. Polymerase Chain Reaction (PCR) helps in early detection of diseases or pathogens by the amplification of their nucleic acid. PCR can amplify nucleic acids of pathogens even when their concentration is very low. This technique can be used for detecting HIV in suspected AIDS patients, genetic mutations in suspected cancer patients and in identifying genetic disorders.
2. Enzyme Linked Immuno Sorbent Assay (ELISA) is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens (proteins, glycoproteins, etc.) or by detecting the antibodies synthesised against the pathogen.