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. MCQ with Answer and Explanation
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. A true, R false.
B. Both A and R are true, and R is the correct explanation.
C. Both A and R are true, but R is not the correct explanation.
D. A false, R true.
Answer: Option B
Solution (By JKSSB Mock Tests)
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:
Lacrimal glands, located above the outer corner of each eye, produce tears that lubricate and protect the eye surface. Parotid and sublingual are salivary glands, ceruminous glands produce ear wax.
Explanation:
Phototropism (positive in shoots) is caused by the migration of auxin to the shaded side of the shoot, promoting cell elongation more on that side, causing the shoot to bend towards light. This asymmetric auxin distribution was demonstrated by Went's experiments. Auxin is sensitive to light and moves laterally. This is a growth response to directional light.
Explanation:
Humans are ureotelic—they excrete nitrogenous waste mainly as urea, which is less toxic than ammonia and requires moderate water for excretion. Ammonia is excreted by aquatic animals, uric acid by birds and reptiles (to conserve water), and creatinine is also excreted but is a minor component compared to urea.
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