NEET Biology 2

Question 1

Which enzyme is responsible for unwinding the DNA double helix during replication?

Accepted Answer

Helicase

Answer

Helicase breaks hydrogen bonds between base pairs to unwind the double helix at the replication fork.

Question 2

The process by which plants lose water through aerial parts other than stomata is called:

Accepted Answer

Cuticular transpiration

Answer

Cuticular transpiration is water loss through the cuticle of leaves, accounting for about 5–10% of total transpiration.

Question 3

Which of the following correctly describes the lac operon in the presence of lactose and absence of glucose?

Accepted Answer

CAP-cAMP activates; operon ON

Answer

Low glucose raises cAMP, allowing CAP-cAMP to bind and activate transcription; lactose removes the repressor, so the operon is fully ON.

Question 4

Biotic potential refers to:

Accepted Answer

Intrinsic rate of natural increase under ideal conditions

Answer

Biotic potential (r) is the maximum reproductive rate of a population under ideal, unlimited environmental conditions.

Question 5

In which phase of meiosis does crossing over occur?

Accepted Answer

Pachytene of Prophase I

Answer

Crossing over (chiasmata formation) occurs during pachytene of Prophase I when homologous chromosomes are fully synapsed.

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