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
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, 2 and 3
B. 1 and 3 only
C. 1 and 2 only
D. 2 and 3 only
Answer: Option C
Solution (By JKSSB Mock Tests)
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.
Explanation:
Atrial Natriuretic Peptide (ANP) is a hormone secreted by the atrial myocytes (muscle cells) of the heart in response to excessive stretching of the atrial walls, which occurs when blood volume and pressure are high. ANP acts to lower blood pressure and volume by promoting vasodilation and increasing the excretion of sodium (natriuresis) and water by the kidneys. It also inhibits the renin-angiotensin-aldosterone system (RAAS) and the release of ADH.
Explanation:
Kidneys are bean-shaped organs that filter waste products, excess water, and electrolytes from the blood to form urine. The liver processes nutrients and toxins, the heart pumps blood, the lungs exchange gases.
Explanation:
Alveoli are tiny, thin-walled air sacs surrounded by a network of pulmonary capillaries. Oxygen diffuses from alveolar air into blood, and CO₂ diffuses from blood into alveolar air. Bronchi and bronchioles are air passages, trachea is the windpipe. The large surface area of alveoli (about 70 m²) facilitates efficient gas exchange.
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