Biology 12 Biotechnology and Its Applications – Chapter 12 Exercise

Q 1. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because –

  1. Bacteria are resistant to the toxin
  2. Toxin is immature
  3. Toxin is inactive
  4. Bacteria encloses toxin in a special sac.
Ans 1. Toxin is inactive.
Q 2. What are transgenic bacteria? Illustrate using any one example.
Ans 2. When a foreign gene or series of gene are intentionally introduced into the genone of a bacterium, the later becomes transgenic. For examples, two DNA sequences (A and B chains of human insulin) were introduced into plasmid of bacteria E. coli. The transgenic bacteria start producing insulin chains.
Q 3. Compare and contrast the advantages and disadvantages of production of genetically modified crops.

Ans 3. Advantages: transgenic plants have definitely several advantages such as –

  1. They increase productivity of crops generally by showing resistance against plant pathogens and to come herbicides.
  2. They develop are develop crop varieties with added vitamins and minerals. Thus, the GM crops have enhanced nutritional quality and yield.
  3. Transgenic crops grow well in saline soil and show salt tolerance.

Disadvantages: However, the introduction of transgenic crops into agriculture has also created controversies. Transgenes in commercial crops can endanger native species.
For example, the gene for Bt toxin expressed in pollen might endanger pollinators like honeybees. These crops cause problems in human health by suppling allergens and transfer of antibiotic resistance markers. They cause damage to the natural environment. Transgenic crops are always costly so that they are adverse to the interest of the farmers.

Q 4. What are cry protein? Name an organism that produce it. How has man exploited this protein to his benefit.
Ans 4. Cry proteins are encoded by the genes named cry. They are produced in bacillus thuringiensis. Cry proteins are toxic to insects and act as insecticides. Man has developed several transgenic crops by introducing these genes from bacteria to crop plants such as Bt cotton, Bt corn, tomato, etc.
Q 5. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.
Ans 5. Genetic engineering may one day enable the medical scientists to place the defective gene responsible for hereditary diseases (hemophilia, phenylketonuria) with the normal genes. This new system of medicine is called gene therapy.gene theapy

Q 6. Diagrammatically represent the experimental steps in cloning and expressing the human gene (say the gene for growth hormone) into a bacterium like E. Coli.

Ans.

human gene

Q 7. Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of rDNA technology and chemistry of oil?
Ans 7. It involves metabolic engineering to transform an oil (hydrocarbon) producing seed into a oil-less seed. This can be done by identifying the specific enzyme involved in biosynthesis of oil and then repressing the gene plant and also genes from some bacteria. Golden rice will prevent child blindness caused due to deficiency of Vit. A.
Q 8. Find out from internet what is golden rice.
Ans 8. Developed as swiss federal institute of technology, golden rice is a transgenic variety of rice rich in vitamin A (Beta Carotene). The rice grains are golden-yellow in color. It contains ‘beta carotene gene’ from daffodil plant and also genes from some bacteria. Golden rice will prevent child blindness caused due to deficiency of vitamin A.
Q 9. Does our blood have proteases and nucleases?
Ans 9. Yes, our blood contains proteases and nucleases which help to degrade the foreign agents such as proteins and genetics materials.
Q 10. Consult internet and find out how to make orally active protein pharmaceutical. What is the major problem to be encountered?
Ans 10. What active protein pharmaceuticals are taken orally, the major problem that is encountered is their degradation by the enzymes and acidic medium. To overcome these problems, the pharmaceutical proteins must be coated by a film that is resistant to these degrading factors.
Updated: October 7, 2020 — 12:17 pm

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