Consider statements about environment: 1. Biochemical Oxygen Demand (BOD) measures organic pollution. 2. Eutrophication is caused by excess nutrients. 3. Biological magnification decreases at higher trophic levels. Which are correct? MCQ with Answer and Explanation

Question

Consider statements about environment: 1. Biochemical Oxygen Demand (BOD) measures organic pollution. 2. Eutrophication is caused by excess nutrients. 3. Biological magnification decreases at higher trophic levels. Which are correct?

A. 1 and 2 only

B. 1 and 3 only

C. 2 and 3 only

D. 1, 2 and 3

Answer: Option A

Solution (By JKExamLibrary)

Biochemical Oxygen Demand (BOD) measures the amount of dissolved oxygen required by aerobic bacteria to decompose organic matter in water; high BOD indicates severe organic pollution. Eutrophication is the excessive enrichment of water bodies with nutrients (like nitrates and phosphates), leading to algal blooms and oxygen depletion. Biological magnification is the progressive increase in the concentration of non-biodegradable toxins (like DDT) at each successive trophic level, not a decrease. Thus, statements 1 and 2 are correct.

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Question #1

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Kwashiorkor is a severe form of malnutrition primarily caused by:

A. Protein deficiency

B. Vitamin A deficiency

C. Calorie deficiency

D. Iron deficiency

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Correct Answer: Option A

Explanation:
Kwashiorkor is a severe form of malnutrition in children caused by a significant deficiency of protein in the diet, despite potentially adequate calorie intake. It is characterized by edema (swelling, especially in the belly due to low albumin), an enlarged liver, thinning hair, and a 'flaky paint' skin rash. Marasmus is caused by overall protein-calorie deficiency.

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Question #2

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Double fertilization in angiosperms involves the fusion of one male gamete with the egg and the other male gamete with:

A. Antipodals

B. Synergids

C. Central cell (secondary nucleus)

D. Helping cells

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Correct Answer: Option C

Explanation:
Double fertilization is a unique feature of angiosperms. One male gamete fuses with the egg cell to form the diploid zygote (syngamy), which develops into the embryo. The second male gamete fuses with the diploid secondary nucleus (polar nuclei) of the central cell to form the triploid Primary Endosperm Nucleus (PEN), which develops into the endosperm.

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Question #3

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The disease caused by the bacterium Treponema pallidum is:

A. Chlamydia

B. Chancroid

C. Gonorrhea

D. Syphilis

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Correct Answer: Option D

Explanation:
Syphilis is a sexually transmitted infection caused by the spirochete Treponema pallidum. Gonorrhea is Neisseria gonorrhoeae, chlamydia Chlamydia trachomatis.

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