The hormone that stimulates milk ejection during breastfeeding is: MCQ with Answer and Explanation

The hormone that stimulates milk ejection during breastfeeding is:
A. Prolactin
B. Oxytocin
C. Progesterone
D. Estrogen
Answer: Option B
Solution (By JKSSB Mock Tests)
Oxytocin, released from the posterior pituitary in response to suckling, causes contraction of myoepithelial cells around mammary alveoli, forcing milk into ducts (let-down reflex). Prolactin stimulates milk synthesis. Estrogen and progesterone inhibit milk secretion during pregnancy.

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Practice More Biology Questions

Question #1
The type of muscle tissue that is voluntary and striated is:
A. Visceral muscle
B. Smooth muscle
C. Skeletal muscle
D. Cardiac muscle

Correct Answer: Option C


Explanation:
Skeletal muscle is attached to bones, is under voluntary control, and has a striated appearance due to the arrangement of actin and myosin filaments. Smooth muscle (visceral) is non-striated and involuntary, found in internal organs. Cardiac muscle is striated but involuntary, found only in the heart. Skeletal muscles are multinucleated.

This question belongs to: Science Biology
Question #2
The process by which a cell engulfs a solid particle is termed:
A. Pinocytosis
B. Osmosis
C. Phagocytosis
D. Exocytosis

Correct Answer: Option C


Explanation:
Phagocytosis ('cell eating') is a type of endocytosis where the cell membrane extends pseudopodia around a solid particle (e.g., bacterium) and engulfs it into a phagosome, which later fuses with a lysosome for digestion. Pinocytosis is 'cell drinking' of fluids. Exocytosis is secretion. Osmosis is water movement across a membrane.

This question belongs to: Science Biology
Question #3
The subunits of 80S ribosomes in eukaryotes are:
A. 30S + 50S
B. 60S + 40S
C. 50S + 30S
D. 40S + 60S

Correct Answer: Option D


Explanation:
Eukaryotic ribosomes are 80S and composed of a small 40S subunit and a large 60S subunit. Prokaryotic ribosomes are 70S with 30S and 50S subunits. The S (Svedberg) value is a measure of sedimentation rate, not simply additive. Both ribosome types synthesize proteins, but the structural difference allows selective antibiotic targeting (e.g., streptomycin acts on 70S).

This question belongs to: Science Biology