Identify the correct statement with regard to
G1 phase (Gap 1) of interphase.
AI-generated explanation. Check against your textbook.
Explanation:
During G1 (the first gap phase) of interphase, the cell is metabolically active and grows in size. It does not replicate its DNA; DNA replication occurs in the S phase. G1 prepares the cell for DNA synthesis by producing RNA and proteins required for DNA replication and by increasing cytoplasmic components. Therefore, the correct statement is 3: “Cell is metabolically active, grows but does not replicate its DNA.”
🧠 Did You Know?
G1 is followed by S phase, then G2; together these phases constitute interphase, before mitosis (M phase).
💡 NCERT Memory Line:
“In G1, the cell grows and carries out normal metabolic activities; DNA replication occurs later in S phase.”
The number of substrate level phosphorylations
in one turn of citric acid cycle is:
AI-generated explanation. Check against your textbook.
Explanation:
In one turn of the citric acid cycle, substrate-level phosphorylation occurs once. Succinyl-CoA synthetase converts succinyl-CoA to succinate and produces one GTP (or ATP, depending on the organism). Thus, the number of substrate-level phosphorylations per cycle is one. Options Zero, Two, or Three do not match this NCERT-stated observation.
🧠 Did You Know?
Only one molecule of GTP/ATP is formed per cycle by substrate-level phosphorylation; the rest of the cycle’s energy is captured in NADH and FADH2 during redox reactions.
💡 NCERT Memory Line:
In one turn of the TCA cycle, one substrate-level phosphorylation yields one GTP (ATP) molecule.