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Biology - Extreme

This one shows no mercy. Good luck solving NEET level problems.

1. Which region of the lac operon is bound by the repressor protein in the absence of an inducer like lactose or allolactose?

Operator region (\(o\))
Promoter region (\(p\))
Structural gene \(z\)
Regulator gene (\(i\))

2. In human spermatogenesis, at which stage does the first meiotic reduction division occur, resulting in haploid cells?

Primary spermatocyte to Secondary spermatocyte
Spermatogonia to Primary spermatocyte
Secondary spermatocyte to Spermatid
Spermatid to Spermatozoa

3. What is the specific role of the restriction endonuclease EcoRI when cleaving double-stranded DNA?

Cuts specifically between G and A in 5'-GAATTC-3' producing sticky ends
Cuts specifically between A and T in 5'-AAGCTT-3' producing blunt ends
Removes nucleotides from the 5' end non-specifically
Joins Okazaki fragments together

4. Which hormone acts via a second messenger system involving cyclic AMP (cAMP) rather than nuclear receptor binding?

Epinephrine / Adrenaline
Estrogen
Progesterone
Cortisol

5. In the cardiac cycle, what causes the second heart sound ('dup')?

Closure of semilunar valves at the onset of ventricular diastole
Closure of atrioventricular (tricuspid/bicuspid) valves during ventricular systole
Opening of AV valves during atrial systole
Rapid inflow of blood into the ventricles