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CBSE PMT - Biology Multiple Choice Questions with Answers

(31) How many nucleosomes are found in helical coil of 30 nm chromatin fibre?
[A] 10
[B] 12
[C] 06
[D] 09

Comment

Answer: Option [C]

The correct answer is 06. The length of a helical coil of 30 nm chromatin fibres forming a solenoid contains 6 nucleosomes per turn of a solenoid.

(32) If the number of chromosomes in most body cells of a mammal is 40, the cells in the seminiferous tubule will have
[A] 40 chromosomes
[B] 20 chromosomes
[C] 10 chromosomes
[D] While some other will have 20

Comment

Answer: Option [D]

The correct answer is While some other will have 20. Reduction division takes place during spermatogenesis. Spermatids and sperms will have haploid number of chromosomes.

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(33) Balbiani discovered special type of chromosome from the salvary gand of chironomus larva which are recognized by the presence of
[A] Bands
[B] Loops
[C] Both bands and loops
[D] All of the above

Comment

Answer: Option [C]

The correct answer is Both bands and loops. Polytene chromosomes are over-sized chromosomes which have developed from standard chromosomes and are commonly found in the salivary glands of Drosophila melanogaster. Specialized cells undergo repeated rounds of DNA replication without cell division to increase cell volume, forming a giant polytene chromosome. Polytene chromosomes have characteristic light and dark banding patterns that can be used to identify chromosomal rearrangements and deletions. Dark banding frequently corresponds to inactive chromatin, whereas light banding is usually found at areas with higher transcriptional activity.

(34) A cistron is
[A] Structural of gene
[B] Functional unit of RNA
[C] Functional unit gene
[D] Replication unit of gene

Comment

Answer: Option [C]

A cistron is Functional unit gene. Functional unit of gene is cistron. A cistron is a gene. The term cistron is used to emphasize that genes exhibit a specific behavior in a cis-trans test; distinct positions or loci within a genome are cistronic.

(35) Genetic information are carried in the form of long chain of molecules made-up-of
[A] Amino acids
[B] RNA
[C] Nucleotides
[D] Polypeptides

Comment

Answer: Option [C]

The correct answer is Nucleotides. Genetic information is carried in the linear sequence of nucleotides in DNA. Each molecule of DNA is a double helix formed from two complementary strands of nucleotides held together by hydrogen bonds between G-C and A-T base pairs.

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