The double fertilization characteristic of angiosperms results in the formation of:
A. Zygote and endosperm
B. Zygote and embryo sac
C. Two embryos
D. Two zygotes
Answer: Option A
Solution (By JKExamLibrary)
Double fertilization involves one male gamete fusing with the egg cell to form a diploid zygote, and the second male gamete fusing with the two polar nuclei (central cell) to form a triploid primary endosperm nucleus. The endosperm provides nutrition to the developing embryo. This unique feature ensures efficient nutrient supply and is typical of angiosperms.
Explanation:
Rickets is characterized by weak, soft bones, bowed legs, and growth retardation due to impaired calcium deposition. In adults, equivalent is osteomalacia. Scurvy is vitamin C, pellagra niacin.
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:
Salivary amylase (ptyalin) hydrolyzes starch into maltose and dextrins in the mouth. It functions optimally at neutral to slightly alkaline pH. Pepsin digests proteins in the stomach, lipase digests fats, trypsin is a pancreatic protease. Salivary amylase action ceases in the acidic stomach.
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