Question

Read the following four statements (A-D)
A. In transcription, adenine pairs with uracil.
B. Regulation of lac operon by repressor is referred to as positive regulation.
C. The human genome has approximately 50,000 protein coding genes.
D. Haemophilia is a sex-linked recessive disease.

How many of the above statements are right?
(i) Three
(ii) Four
(iii) One
(iv) Two

Answer 1

Hint: Transcription is the process of synthesizing the mRNA from the DNA where it is formed inside the nucleus. lac operon is an operon required for the transport and metabolism of lactose in E.coli, and genome is the set of multiple numbers of genes. and hemophilia is a genetic disease. transfer by the inheritance.

Complete answer:
A. Transcription is process of mRNA from the DNA by the enzyme RNA polymerase, and in this process the enzyme read the bases on the DNA and complementary strand is formed, which is mRNA, but the nucleotide pairs are some in both the DNA and the mRNA which is formed except for the thymine, where thymine is absent in the RNA, generally adenine and thymine are the complementary base pairs as thymine is absent it is replaced by uracil. So it is the correct option.

B. In the microorganisms like E.coli for the transport and the metabolism of the lactose an operon required which is generally referred to as a negative regulation. So this is wrong option.

C. Human genome is the complete set of nucleic acids sequences found in the 23 sets of chromosomes in the nucleus as DNA, an average human genome has a range of 20,000 to 30,000 genes that makes three proteins. So the given option is wrong.

D. Hemophilia is an sex linked recessive disease, where it is mainly inherited by the recessive gene on X chromosomes, and mostly males are affected than the females because, in the males X chromosome is only obtained from the mother, so even the mother is carrier there is 50% chance for the males to get the disease, so It is correct answer.

Hence, the correct answer is option (iv) that is Two.

Note: Hemophilia Is a genetic disorder where the person has lack of some clotting factors, which makes them bleed for a long time whenever there are injuries and all. And it is mainly inherited by the X chromosomes, and the genes are recessive genes.