Q91. Which of the following enzymes is responsible for synthesizing the leading strand during DNA replication?
(a) Helicase
(b) Ligase
(c) DNA polymerase
(d) Primase
Answer: (c) DNA polymerase
Explanation: DNA polymerase synthesizes the leading strand continuously in the 5′ to 3′ direction during DNA replication.
Q92. Which of the following is true for RNA but not for DNA?
(a) It is double-stranded.
(b) It contains deoxyribose.
(c) It contains uracil.
(d) It contains thymine.
Answer: (c) It contains uracil.
Explanation: RNA contains uracil instead of thymine, which is found in DNA. Additionally, RNA contains the sugar ribose, while DNA contains deoxyribose.
Q93. The process of copying a gene’s DNA sequence into an mRNA sequence is called:
(a) Translation
(b) Transcription
(c) Replication
(d) Mutation
Answer: (b) Transcription
Explanation: Transcription is the process by which a gene’s DNA sequence is copied into messenger RNA (mRNA), which is then used for protein synthesis.
Q94. Which of the following nitrogenous bases pairs with adenine in RNA?
(a) Thymine
(b) Cytosine
(c) Guanine
(d) Uracil
Answer: (d) Uracil
Explanation: In RNA, uracil pairs with adenine, replacing thymine, which is found in DNA.
Q95. Which of the following processes occurs in the nucleus of eukaryotic cells?
(a) Translation
(b) Transcription
(c) Protein synthesis
(d) Glycolysis
Answer: (b) Transcription
Explanation: Transcription occurs in the nucleus of eukaryotic cells, where the DNA is located. Translation and protein synthesis occur in the cytoplasm.
Q96. What is the function of tRNA in protein synthesis?
(a) Carry genetic information
(b) Synthesize ribosomes
(c) Transport amino acids
(d) Catalyze peptide bond formation
Answer: (c) Transport amino acids
Explanation: Transfer RNA (tRNA) carries amino acids to the ribosome, where they are added to the growing polypeptide chain during protein synthesis.
Q97. The bonds that link nucleotides together in a nucleic acid strand are called:
(a) Peptide bonds
(b) Glycosidic bonds
(c) Phosphodiester bonds
(d) Hydrogen bonds
Answer: (c) Phosphodiester bonds
Explanation: Phosphodiester bonds link nucleotides together in the sugar-phosphate backbone of nucleic acid strands (DNA and RNA).
Q98. Which of the following statements about DNA and RNA is false?
(a) DNA is double-stranded; RNA is single-stranded.
(b) DNA contains deoxyribose; RNA contains ribose.
(c) DNA uses thymine; RNA uses uracil.
(d) Both DNA and RNA are involved in protein synthesis.
Answer: (d) Both DNA and RNA are involved in protein synthesis.
Explanation: While DNA contains the instructions for protein synthesis, it is not directly involved in the process. Only RNA (mRNA, tRNA, and rRNA) directly participates in protein synthesis.
Q99. The site where translation occurs in a eukaryotic cell is:
(a) Nucleus
(b) Ribosome
(c) Mitochondria
(d) Golgi apparatus
Answer: (b) Ribosome
Explanation: Translation occurs at the ribosome, where mRNA is used as a template to assemble amino acids into proteins.
Q100. The function of RNA polymerase is to:
(a) Synthesize RNA from a DNA template
(b) Synthesize DNA from an RNA template
(c) Synthesize proteins from RNA
(d) Break down RNA
Answer: (a) Synthesize RNA from a DNA template
Explanation: RNA polymerase is the enzyme responsible for synthesizing RNA from a DNA template during the process of transcription
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