Biotechnological Applications in Agriculture (NCERT) - Free MCQ Practice

Bt toxin gene has been closed from the bacteria and expressed in plants to provide resistance to insects without the need for insecticides. Examples are Bt cotton, Bt corn, rice, tomato, potato and soybean, etc.

The development of several high yielding varieties of wheat and rice in 1960 increased yields per unit area. This phase is often called the Green Revolution. However, for farmers in the developing world, agrochemicals are often too expensive, and further increase in yield with existing varieties are not possible using conventional breeding. Thus, it has not fully succeeded in making India totally self-sufficient in food with only some parts showing impressive results.

• Statement 1: The tumour-inducing plasmid (Ti plasmid) acts as a cloning vector in recombinant DNA technology.
  The Ti plasmid, derived from Agrobacterium tumefaciens, is widely used in recombinant DNA technology as a cloning vector to deliver genes into plant cells. The T-DNA (transfer DNA) region of the Ti plasmid is modified to carry the desired gene, which is then transferred into the plant genome. This statement is correct.
• Statement 2: The Ti plasmid, which is used in the mechanisms of delivering genes to a cell, remains pathogenic.
  In its natural form, the Ti plasmid is pathogenic because it causes crown gall disease in plants by transferring T-DNA, which includes genes that induce tumor formation. However, in recombinant DNA technology, the Ti plasmid is modified by removing the tumor-inducing genes (oncogenes) from the T-DNA region, replacing them with the gene of interest. This modified Ti plasmid is no longer pathogenic; it is disarmed to prevent tumor formation while retaining its ability to transfer DNA. Therefore, this statement is incorrect.

Correct Answer:

b) Statement 1 is correct but statement 2 is incorrect

MCQ Solution:

• a) Incorrect: Statement 2 is incorrect, so both cannot be correct.
• b) Correct: Statement 1 is true (Ti plasmid is used as a cloning vector), but Statement 2 is false (the modified Ti plasmid is not pathogenic).
• c) Incorrect: Statement 1 is correct, not incorrect.
• d) Incorrect: Statement 1 is correct, so both are not incorrect.

Thus, the correct answer is b).

Soil bacterium, Bacillus thuringiensis (Bt) produces proteins that kill certain insects like lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). Bacillus thuringiensis forms some intracellular protein crystals. These crystals contain a toxic insecticidal protein. The Bt toxin protein exists as inactive toxin and is converted into an active form due to the alkaline pH of the alimentary canal that solubilises the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores which cause cell swelling and lysis and finally cause death of the insect.

The transgenic food, containing enyme produced by antibiotic gene, can cause allergies because it is a foreign protein. The bacteria present in alimentary canal can take up antibiotic resistance gene and become resistant to that antibiotic. Transgenes can endanger native species if Bt toxin is expressed in pollens which are transported by pollinator honeybees. GM crop production causes changes in natural environment which may be harmful for all organisms.

Lepidopterans are an order of insects consisting of moths and butterflies. Some insects of this order can be killed by the bacteria Bacillus thuringiensis. A few examples of lepidopterans are tobacco budworm, armyworm, bettles, etc.

RNAi or RNA interference takes place in all eukaryotic organisms as a method of cellular defense. This method involves silencing of a specific mRNA. Using Agrobacterium vectors, nematode specific genes are introduced into the host plant (tobacco plant). The introduction of DNA was such that it produced both sense and anti-sense RNA in the host cells. These two RNAs being complementary to each other formed a dsRNA (double stranded RNA) that initiated RNAi.

Genetic engineering is the artificial synthesis, isolation, modification, combination, addition and repair of the genetic material (DNA) to alter the phenotype of the host organism to suit human needs. It is the manipulation of genes by man in vitro. Restriction endonucleases play major role in genetic engineering as they can cut DNA at specific sites.

Two cry genes, crylAc and cryllAb have been incorporated in cotton. The genetically modified crop is called Bt cotton as it contains Bt toxin genes. The genes crylAc and cryllAb control cotton bollworms.

Rice is a staple food in many countries, particularly in Asia, but does not contain vitamin A or its immediate precursors. By inserting two genes from Daffodil and one gene from a bacterial species into rice plants, Swiss researchers have produced rice capable of synthesising β-carotene, the precursor of vitamin A. Vitamin A is required by all individuals as it is present in retina of eyes. Deficiency of vitamin A causes night blindness and skin disorders. This rice is called 'Golden rice' because of yellow colour of rice grains due to the presence of β-carotene.

Rearing of honeybees for obtaining honey and bee wax is called apiculture. It is not a biotechnological application. 

Agrochemical based agriculture is used to increase the food production. It includes use of agrochemicals such as fertilisers and pesticides.

Genetic modification has:
(i) Made crops more tolerant to abiotic stresses (cold, drought, salt, heat)
(ii) Reduced reliance on chemical pesticides (pest-resistant crops)
(iii) Helped to reduce post harvest losses
(iv) Increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility of soil)
(v) Enhanced nutritional value of food e.g., golden rice, i.e., vitamin 'A' enriched rice.

In addition to these uses, GM has been used to create tailor-made plants to supply alternative resources to industries, in the form of starch, fuel, and pharmaceuticals. 

Meloidogyne incognita infects the roots of tobacco plants and causes great reduction in yield. Fire and Mello (1998) invented a novel strategyt to prevent this infestation. It was based on the process of RNA interference.

CrylAb has been introduced in Bt corn to protect it from corn borer.

Bacillus thuringiensis is not used as a bio-fertitiser but it is used to create transgenic plants.

Crops in which foreign genes been introduced through genetic engineering are called genetically modified crops or GM foods. There have been many health and safety concern, therefore, such foods undergo lots of examination before release.

Hirudin is a protein that prevents blood clotting. Its gene was chemically synthesized and was transferred into Brassica napus where hirudin accumulates in seeds. The hirudin is extracted and purified and then used as medicine.

Weeds such as Striga decrease crop yields and quality by competing with crop plants for light, water and nutrients. Weeds are to be removed with the help of herbicide (weed killer) Herbicide tolerance has been developed in maize, cotton, soybean, tobacco, etc. The main aim is to reduce herbicide accumulation in food products for health safety.

The Government has agreed to allow cultivation of genetically modified Bt Cotton. Bt cotton farming has shown good results in Malwa region in punjab

Transgenic Bt cotton, which produces its own insecticide contains a gene from a soil bacterium (Bacillus thuringiensis). Bt Cotton is usually resistant to bollworm disease of cotton

In organic farming, farmers use manures, bio fertilisers, biopesticides and biocontrol agents to increase the crop production instead of using artificial fertilisers and pesticides. It does not utilise genetic engineering, which makes statement (i) false. Statement (ii) is correct as organic farming uses naturally produced inputs like compost and biofertilisers. Statement (iii) is correct because organic farming avoids synthetic pesticides and commercial fertilizers like urea. Lastly, statement (iv) is considered correct as organically grown vegetables are often noted for being rich in vitamins and minerals due to the natural farming practices employed.

Conversion of pro Bt toxin to Bt toxin takes place in highly alkaline conditions which are not present in human stomach. Human stomach is acidic in nature.

Transgenic techniques in crops can make crops more resistant to many detrimental factors.
This confers pest resistance and temperature adjustability and avoiding the use of harmful synthetic pesticides.
But the pant or crop does not remain completely Organic in nature.
So, the correct option is 'Public preference for organic vegetables'.

There are a number of them, for example, the proteins encoded by the genes cryIAc and cryIIAb control the cotton bollworms, that of cryIAb controls corn borer.