FREE NEET Biology Practice MCQ Test: Biotechnology And Its Applications Exercise 2 Questions Answers With Detailed Explanations [PDF]

Answer: (c)

Answer: (b)

Bt toxin genes were isolated from Bacillus thuringiensis and incorporated into several crop plants such as cotton. The choice of genes depends upon the crop and the targeted pest, as most of Bt toxins are insect group specific. The toxin is coded by gene named cry. Two cry genes - cry I Ac and cry II Ab have been incorporated in cotton. The proteins encoded by genes cry II Ab and cry I Ac control cotton bollworms and that of cry I Ab controls corn borer.

Answer: (c)

Bt toxins are inactive protoxins but after ingested by the insect, these inactive toxin becomes active, due to the alkaline pH of the gut, that solubilise the crystals. Hence, high pH value is required to make Bt toxins active. Under high temperature and acidic pH, Bt toxins remain insoluble and inactive.

Answer: (a)

In this technique nematode specific genes are introduced in the host plant in such a way that it produces both sense and antisense RNA. The two RNA's being complementary to each other form a double stranded RNA (dsRNA) which is also called interfering RNA responsible for initiating RNA interference (RNA i). This (dsRNA) bind to and prevent translation of specific mRNA of nematode (gene silencing). Thus transgenic plants based on RNAi technology are resistant to nematode.

Answer: (d)

Answer: (b)

Answer: (c)

Gene silencing could be achieved through various routes including RNAi and the use of antisense RNA.

Answer: (a)

Answer: (d)

The application of biotechnology includes waste treatment, energy production and genetically modified crops for agriculture. It does not include conventional hybridisation technique.

Answer: (d)

DNA fingerprinting is a technique of determining nucleotide sequences of certain areas of DNA which are unique to each individual. The difference of about 0.1% or 3 × $10^6$ base pairs (out of 3 × $10^9$ bp) provides individuality to each human being. Human genome possesses numerous small noncoding but inheritable sequences of bases which are repeated many times. These sequences occur near telomere, centromeres, Y chromosome and heterochromatic area. The area with same sequence of bases repeated several times is called repetitive DNA. It is separated as satellite from the bulk DNA during density gradient centrifugation and hence called satellite DNA where, repetition of bases is in tandem. Satellite DNAs show polymorphism (the occurrence of mutations in a population at high frequency), which is the basis of genetic mapping of human genome as well as DNA fingerprinting. While mutations in genes produce alleles with different expressions, mutations in noncoding repetitive DNA have no immediate impact. These mutations which have piled up with time form the basis of polymorphism.

Answer: (a)

Although DNA fingerprinting is a powerful technique, a genetic match call demonstrate only a high probability of guilt since there is a 1/100,000 to l /1,000,000,000 chance that two individuals will share the same genetic profile.

Answer: (a)

Answer: (b)

Mammalian hormones were among the first products prepared in bacteria by r-DNA technology. Human insulin and human growth hormone are earliest examples.

Answer: (c)

Answer: (d)

Answer: (c)

The plants produced through genetic engineering contain gene or genes usually from an unrelated organism. Such genes are called transgenes and the plants having transgenes are called transgenic plants. Recombinant DNA techniques are being used to improve crop plants by increasing their productivity, by making them more nutritious and by developing disease resistance. Transgenic plants may have resistance to herbicides, pests and abiotic stresses.

Answer: (d)

Answer: (a)

Answer: (d)

In 1997, the first transgenic cow, Rosie, produced human protein enriched milk. The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cowmilk. Isolation of DNA from other macromolecule is achieved by treating the bacterial cells/plant or animal tissue with enzymes such as lysozyme (bacteria), cellulase (plant cells), chitinase (fungus).

Answer: (d)