:
During the early 1900s, scientists thought that protein was the basic genetic material that contains hereditary information. However, later experiments proved that DNA is the genetic material in mostorganisms.

Answer: Option C. -> Promoter gene, operator gene, structural genes
:
C
The lac operon of E.coli consists of a promoter gene, operator gene and three structural genes, all of which work together to digest lactose. There is also a regulator gene which is usually present outside the operon, but is essential, as it codes for the repressor protein.

Answer: Option C. -> Hugo de Vries
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C
Mutation was first observed by Hugo de Vries in 1886 while studying the evening primrose Oenothera lamarckiana. He noticed wild varieties of the plant that differed from the original cultivated species.

Answer: Option D. -> Okazaki and Okazaki
:
D
DNA replication is ‘semi-discontinuous’ because one of the strands is synthesised continuously, while the other strand, discontinuously by the formation of Okazaki fragments. This was discovered in the year 1968 by a Japanese scientist couple - Reiji Okazaki and his wife Tsuneko Okazaki. The term‘Okazaki fragments’ has been givenafter them.

Answer: Option A. -> True
:
A
The four types of nitrogenous bases found in DNA are adenine, guanine, cytosine and thymine. Out of which adenine and guanine are the purines, while cytosine and thymine are the pyrimidines. Same purines are present in RNA as well. But pyrimidines in RNA are cytosine anduracil.

Answer: Option C. -> A is true and R is false
:
C
Gene expression results in the formation of a protein, and hence, involves both transcription and translation. This however, is controlled by various mechanisms in different organisms. The phenomenon by which expression of these genes is regulated is known as gene regulation. This basically means that gene regulation involves switching on or off of the genes.

Answer: Option C. -> Hugo de Vries
:
C
Mutation was first observed by Hugo de Vries in 1886 while studying the evening primrose Oenothera lamarckiana. He noticed wild varieties of the plant that differed from the original cultivated species.

Answer: Option B. -> Promoter
:
B
Introns and exons are formed in a process called post-transcriptional modification. This takes place after transcription is carried out. Therefore before transcription, they are found combined together and are collectively known as the RNA coding region or the Gene. The terminator sequence is also required for the RNA polymerase to stop copying things down and hence included in the transcription unit, although it does not form a part of the structural or core Gene. The promoter however, is present on the strand just to help RNA polymerase recognise the transcription unit. In some cases still, RNA polymerase will be bound to the promoter and another part of the transcription unit, like a repressor, will be blocking its activity, as is the case in the Lac Operon.

Answer: Option C. -> 61
:
C
Of all the 64 codons, three are known as termination codons or stop codons, which do not code for any amino acid. They are UAA, UAG and UGA. They act as stop signals for protein synthesis. Remaining 61 codons code for 20 known amino acids.

Answer: Option A. -> 3’ GGATCTT 5’
:
A
Adenine (A) and guanine (G) are the purines, while thymine (T) and cytosine (C) are the pyrimidines in DNA. A purine always pairs up with a pyrimidine. A and T form a pair, and so do G and C. A base on one DNA strand would form a base pair with its respective counterpart in the complementary strand. The two DNA strands would also run in opposite directions; one of them would be in the 5’-->3’ direction, while the complementary strand would run in the 3’-->5’ direction.