Iodine deficiency primarily affects the function of which gland?
A. Pancreas
B. Thyroid
C. Adrenal
D. Pituitary
Answer: Option B
Solution (By JKSSB Mock Tests)
Iodine is essential for the synthesis of thyroid hormones T₃ and T₄. Deficiency causes hypothyroidism and goiter (enlarged thyroid gland). Iodized salt is a preventive measure.
Explanation:
Prokaryotic cells contain 70S ribosomes, which are composed of a 50S large subunit and a 30S small subunit. The 'S' stands for Svedberg units, a measure of sedimentation rate. Eukaryotic cytoplasm contains 80S ribosomes, though their mitochondria and chloroplasts contain 70S ribosomes.
Assertion (A): Mycorrhizae are symbiotic associations between fungi and plant roots.
Reason (R): The fungus provides water and minerals to the plant and receives sugars in return.
A.Both A and R are true, but R is not the correct explanation.
B.A false, R true.
C.A true, R false.
D.Both A and R are true, and R is the correct explanation.
Explanation:
Mycorrhizae enhance nutrient and water uptake for plants, and the fungus benefits from photosynthetic carbohydrates. It’s a mutualistic symbiosis. R correctly explains A.
Explanation:
Peristalsis is a wave-like series of muscular contractions and relaxations that propels food through the digestive tract. Segmentation mixes contents in the intestine, emulsification breaks fat globules, mastication is chewing.
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