Correct Answer – Option 4 - enzymes

DNA replication occurs with the help of enzymes.

A Scalpel is too large to cut a DNA. Hence, option 1 is incorrect.

Electrophoresis is also not a method that can be used for cutting the DNA. Hence, option 2 is incorrect

Hormones cannot cut the DNA. Hence, option 3 is incorrect.

Correct Answer – Option 1 – may result in the production of a defective protein

A gene mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome.

Gene mutation in a human skin cell cannot alter the sequence of sugars in insulin, cannot decrease mutation rate in offspring and cannot alter the rate of all the metabolic processes in humans. Hence, the options 2,3 and 4 are incorrect.

Correct Answer – Option 3

Variation in offspring's occurs due to cross over. This is quite evident in the figure shown above representing "After"

Correct Answer – Option 4 – The inserted DNA may direct the synthesis of human proteins

The human gene is inserted into a bacterial cell making it a part of the gene of the bacteria. The bacteria will not destroy itself hence cannot destroy the human gene. Hence, option 1 is incorrect.

Embryo cannot be formed by asexual reproduction, which is the mode of reproduction of bacteria. Hence, option 2 is incorrect.

The inserted human DNA does not have full control of the functioning of the cell. Hence, it cannot change the harmful bacteria to harmless one. However it may direct the synthesis of human protein. Hence, option 3 is incorrect and option 4 is the correct answer.

Correct Answer – Option 3

Increase in temperature is does not refer to behavior of the fruit fly or intensity of light, hence, options 1 and 2 are incorrect.

Mutation is an activity taking place with respect to the cell structure and is not governed by temperature however is influenced by the environment, hence, option 3 is the most appropriate answer.

Children B and D have similar DNA profiles. All the bands are located at the same sites, meaning the smallest fragments of both samples have the same molecular sizes. This goes the same with the other bands.

Correct answer: (2) smallest fragment of DNA that traveled the fastest

Band X, which is the band farthest from the wells, represents the smallest fragment that passed through the sponge-like matrix of the gel. It is easier for the smaller molecules to move through the pores of the gel because of their sizes.

Incorrect answers:

(1) largest fragment of DNA that traveled the fastest

It will take a longer time for the largest molecules to travel through the gel because of their sizes.

(3) largest fragment of the DNA that traveled the slowest

Though it is true that the larger fragments move the slowest, it is not true that Band X represents the largest fragment. If the large fragment moves slowly, then it would be the nearest band from the well where the DNA sample was placed.

(4) smallest fragment of DNA that traveled the slowest

Correct answer: (3) genetic engineering-insulin

The diagram illustrates the process of producing insulin through the recombinant DNA technology or genetic engineering. First, a plastid is taken from a bacterial cell. Using a special enzyme, the plastid is opened. DNA from human coding for the synthesis of insulin is inserted into the plasmid. The plasmid and the inserted DNA are closed using another enzyme. The recombined plasmid is then inserted to Escherichia coli, a common bacterium. E. coli divides into new cells with the same genetic makeup as the original. These newly formed cells now produce insulin.

Incorrect answer:

(1) selective-breeding-growth hormone

Selective breeding is a method used in choosing individuals for breeding. It cannot be used to produce growth hormones in bacteria.

(2) cloning-antibiotics

Cloning is the process of producing populations with the same genetic makeup. This is not used to make antibiotics. Mutation is used in the production of antibiotics.

(4) replicating-glucose