The placenta secretes several hormones essential for maintaining pregnancy. Which of the following is NOT primarily secreted by the placenta? MCQ with Answer and Explanation
The placenta secretes several hormones essential for maintaining pregnancy. Which of the following is NOT primarily secreted by the placenta?
A. Prolactin
B. Human Placental Lactogen (hPL)
C. Progesterone
D. Human Chorionic Gonadotropin (hCG)
Answer: Option A
Solution (By JKExamLibrary)
The placenta acts as a temporary endocrine gland, secreting hCG (which maintains the corpus luteum), hPL (which alters maternal metabolism for fetal growth), and high levels of estrogen and progesterone (which maintain the uterine lining and suppress further ovulation). Prolactin, however, is primarily secreted by the anterior pituitary gland, although its levels rise significantly during pregnancy to prepare the mammary glands for lactation.
Explanation:
Biological Oxygen Demand (BOD) is a measure of the amount of dissolved oxygen required by aerobic microorganisms (mainly bacteria) to decompose the organic matter present in a given volume of water sample at a specific temperature over a specific time (usually 5 days at 20°C). High BOD indicates high levels of organic pollution, which depletes oxygen for aquatic life.
Explanation:
Paramecium is a unicellular ciliated protozoan found in freshwater. Earthworm and Hydra are multicellular animals, mushroom is a multicellular fungus. Unicellular organisms carry out all life processes within a single cell.
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?
Explanation:
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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