A) water ava ability. B) temperature C) light intensity. D) atmospheric CO2 leve

Question

A) water ava ability. B) temperature C) light intensity. D) atmospheric CO2 levels. E) atmospheric N2 levels. 79) Molecules assisted by carrier proteins may cross a selectively permeable membrane by: 79) simple diffusion. A) B) osmosis. C) active transport. D) endocytosis E) facilitated diffusion. 80) What is NOT a feature of a prokaryotic cel A) a plasma membrane B) a nuclear membrane C) enzymes D) DNA E) ribosomes 81) Phospholipids spontaneously form a bilayer in an aqueous solution. Why do the heads of the 81) phospholipids point out and the tails point toward another? on A) The tails are repelled by the aqueous environment B) The heads are repelled by the water inside and outside the cell C) The tails are nonpolar and form hydrogen bonds with another. one 82) Mutation is essential for: 82) A) growth and development. B) sperm and egg formation. C) natural selection D) survival E) sexual reproduction. 83) The carbohydrate in DNA is: 83 A) deoxyribose B) phosphate C) ribose D) glucose cellulose E) 84) The formation of sodium chloride (NaCl) is the result of 84) chemical unreactivity. A) covalent bonding. C) the lack of chemical attraction. Dy attraction between opposite charges

Explanation / Answer

79. e.Facilitated diffusion is the process of spontaneous passive transport of molecules or ions across a cell's membrane via specific transmembrane integral proteins.

80.b. Nuclear membrane is not present in prokryotic cells as these cells are devoid of nucleus.

81.a. Since the tails are hydrophobic, they face inside away from the water in the inner region of the membrane and since the heads are hydrophillic, they face outward and are attracted to the intracellular and extracellular fluid.Hence this arrangement occurs in phospholipid bilayer.

82. c. Mutations are actually needed for evolution.These serve as a raw material for evolution but because there is no such option in your question so the best suited option near to the evolution could be natural selection.

83.a.Deoxyribose is a sugar derived from ribose by replacement of a hydroxyl group by hydrogen.

84.d. NaCl contains positive charge in the form of Na+ and negative charge in the form of Cl-.Electrostatic attraction between these oppositely charged ions enable them to come close and form a compound NaCl.

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