Cell Structure & Cell Division

Which organelle is the major site for ATP synthesis via oxidative metabolism and is known as the 'powerhouse of the cell' ?

Which of the following organelles is known as the 'power house' of the cell ?

A chromosome with the centromere situated close to its end, forming one extremely short and one very long arm, is called :

Read the following passage carefully and answer the questions (Q41 - Q45) :

Structure and Chemistry of Nucleic Acids
In RNA, every nucleotide residue has an additional -OH group present at the 2' position in the ribose. Also, in RNA, uracil is found in place of thymine (5-methyl uracil, another chemical name for thymine).
DNA as an acidic substance present in the nucleus was first identified by Friedrich Miescher in 1869; he named it as 'Nuclein'. However, due to technical limitations in isolating such a long polymer intact, the elucidation of the structure of DNA remained elusive for a very long period of time. It was only in 1953 that James Watson and Francis Crick, based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin, proposed a very simple but famous Double Helix model for the structure of DNA. One of the hallmarks of their proposition was base pairing between the two strands of polynucleotide chains. However, this proposition was also based on the observation of Erwin Chargaff that for a double-stranded DNA, the ratios between Adenine and Thymine and between Guanine and Cytosine are constant and equal one.

Question :
Based on the passage, which nitrogenous base is present in RNA but absent in DNA ?

Read the following passage carefully and answer the questions (Q41 - Q45) :

Structure and Chemistry of Nucleic Acids
In RNA, every nucleotide residue has an additional -OH group present at the 2' position in the ribose. Also, in RNA, uracil is found in place of thymine (5-methyl uracil, another chemical name for thymine).
DNA as an acidic substance present in the nucleus was first identified by Friedrich Miescher in 1869; he named it as 'Nuclein'. However, due to technical limitations in isolating such a long polymer intact, the elucidation of the structure of DNA remained elusive for a very long period of time. It was only in 1953 that James Watson and Francis Crick, based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin, proposed a very simple but famous Double Helix model for the structure of DNA. One of the hallmarks of their proposition was base pairing between the two strands of polynucleotide chains. However, this proposition was also based on the observation of Erwin Chargaff that for a double-stranded DNA, the ratios between Adenine and Thymine and between Guanine and Cytosine are constant and equal one.

Question :
According to Chargaff's rules stated in the passage, what is the ratio between Guanine ($G$) and Cytosine ($C$) in double-stranded DNA ?

Read the following passage carefully and answer the questions (Q41 - Q45) :

Structure and Chemistry of Nucleic Acids
In RNA, every nucleotide residue has an additional -OH group present at the 2' position in the ribose. Also, in RNA, uracil is found in place of thymine (5-methyl uracil, another chemical name for thymine).
DNA as an acidic substance present in the nucleus was first identified by Friedrich Miescher in 1869; he named it as 'Nuclein'. However, due to technical limitations in isolating such a long polymer intact, the elucidation of the structure of DNA remained elusive for a very long period of time. It was only in 1953 that James Watson and Francis Crick, based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin, proposed a very simple but famous Double Helix model for the structure of DNA. One of the hallmarks of their proposition was base pairing between the two strands of polynucleotide chains. However, this proposition was also based on the observation of Erwin Chargaff that for a double-stranded DNA, the ratios between Adenine and Thymine and between Guanine and Cytosine are constant and equal one.

Question :
What was the original name given to DNA when it was first identified by Friedrich Miescher in 1869 ?

Read the following passage carefully and answer the questions (Q41 - Q45) :

Structure and Chemistry of Nucleic Acids
In RNA, every nucleotide residue has an additional -OH group present at the 2' position in the ribose. Also, in RNA, uracil is found in place of thymine (5-methyl uracil, another chemical name for thymine).
DNA as an acidic substance present in the nucleus was first identified by Friedrich Miescher in 1869; he named it as 'Nuclein'. However, due to technical limitations in isolating such a long polymer intact, the elucidation of the structure of DNA remained elusive for a very long period of time. It was only in 1953 that James Watson and Francis Crick, based on the X-ray diffraction data produced by Maurice Wilkins and Rosalind Franklin, proposed a very simple but famous Double Helix model for the structure of DNA. One of the hallmarks of their proposition was base pairing between the two strands of polynucleotide chains. However, this proposition was also based on the observation of Erwin Chargaff that for a double-stranded DNA, the ratios between Adenine and Thymine and between Guanine and Cytosine are constant and equal one.

Question :
Who proposed the renowned 'Double Helix' model for the structure of DNA in 1953 based on X-ray diffraction data ?

Meiosis involves one cycle of which of the following?

Choose the correct answer from the options given below :