Science (English Medium) Class 12 - CBSE Question Bank Solutions for Biology

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During copulation, semen is released by the penis into the vegina. The motile sperms swim rapidly, fuse with the ovum in the ampullary region, resulting in fertilization. The haploid nucleus of sperm fuses with that of the ovum to form a diploid zygote.

Site of fertilization in human is ______

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Oogenesis is the process of the formation of an ovum in the ovaries. It consists of three phases: multiplication, growth, and maturation. Oogenesis is controlled by hormones GnRH, LH, FSH. GnRH secreted by the hypothalamus stimulates the anterior lobe of the pituitary gland to secrete LH and FSH.

what is the function of hormones FSH?

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Oogenesis is the process of the formation of an ovum in the ovaries. It consists of three phases: multiplication, growth, and maturation. Oogenesis is controlled by hormones GnRH, LH, FSH. GnRH secreted by the hypothalamus stimulates the anterior lobe of the pituitary gland to secrete LH and FSH.

Which hormone induces the rupture of the mature Graafian follicle?

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Oogenesis is the process of the formation of an ovum in the ovaries. It consists of three phases: multiplication, growth, and maturation. Oogenesis is controlled by hormones GnRH, LH, FSH. GnRH secreted by the hypothalamus stimulates the anterior lobe of the pituitary gland to secrete LH and FSH.

Identify the functions of LH.

1. Release of a secondary oocyte from Graafian follicle.
2. Stimulates corpus luteum to secrete progesterone.
3. Stimulates estrogen formation.
4. Promotes development of egg to form secondary oocyte.

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In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double-helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.

Name the linkage present between the nitrogen base and pentose sugar in DNA.

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In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double-helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.

The double helix structure of DNA was proposed by ______ 

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In prokaryotes, DNA is circular and present in the cytoplasm but in eukaryotes, DNA is linear and mainly confined to the nucleus. DNA or deoxyribonucleic acid is a long polymer of nucleotides. In 1953, the first correct double-helical structure of DNA was worked out by Watson and Crick. Based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin. It is composed of three components, i.e., A phosphate group, a deoxyribose sugar, and a nitrogenous base. Different forms of DNA are B-DNA, Z-DNA, A-DNA, C-DNA, and D-DNA.

The double chain of B-DNA is coiled in a helical fashion. The spiral twisting of the B-DNA duplex produces ______ 

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The process of copying genetic information from the template strand of DNA into RNA is called transcription. It is mediated by RNA polymerase. Transcription takes place in the nucleus of eukaryotic cells. In transcription, only a segment of DNA and only one of the strands is copied into RNA.

Monocistronic structural genes are found in which organisms?

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The translation is the process of polymerization of amino acids to form a polypeptide. The order and sequence of amino acids are defined by the sequence bases in the mRNA. The amino acids are joined by a bond called a peptide bond. The ribosome is the site of protein synthesis.

During translation, how many initiation factors are required in eukaryotes for initiation reactions?

C-peptide of human insulin is ______.

A probe which is a molecule used to locale-specific sequences in a mixture of DNA or RNA Mole cubs could be ______.

The site of production of ADA the body is ______.

A pathophysiology is the ______.

ADA is an enzyme which is deficient in a genetic disorder SCID. What is the full form of ADA?

Choose the correct option regarding retrovirus.

Which of the below mentioned regions exhibit lees seasonal variations?

What is the role of cervix in the human female reproductive system?

Female reproductive organs and associated functions are given below in column A and B. Fill the blank boxes.

Draw a neat diagram of the female reproductive system and label the parts associated with the following:

(a) production of gamete

(b) site of fertilisation

(c) site of implantation

(d) birth canal

With a suitable diagram, describe the organisation of mammary gland.