Which of the following organisms is commonly used as a model organism in genetics? MCQ with Answer and Explanation

Explanation:
The heart is myogenic because the heartbeat originates in the SA node within the heart itself, not from brain signals. The brain can modulate the rate but not initiate. Thus, A is true, but R is false.

Explanation:
Helicase unwinds the DNA helix at the replication fork by breaking hydrogen bonds between base pairs. DNA polymerase adds nucleotides, ligase seals Okazaki fragments, primase synthesizes RNA primer. This coordinated action ensures accurate semi-conservative replication. Without helicase, the strands would not separate. Energy for unwinding comes from ATP hydrolysis.

Explanation:
Bt cotton is a transgenic crop developed by inserting cry genes (e.g., cryIAc, cryIIAb) from the soil bacterium Bacillus thuringiensis (Bt). These genes code for crystal proteins (Cry proteins) that are toxic to certain insect pests, particularly the cotton bollworm. When the insect ingests the protein, it is activated in its alkaline gut, creating pores in the gut lining, leading to the insect's death.