Why is there very little physical evidence of life from rocks of the Archaean eon?
a. Those rocks have been deeply buried in most parts of the world.
b. Those rocks occupy inaccessible areas of mountainous regions.
c. Those rocks have been greatly eroded in most parts of the world.
d. Those rocks occupy the polar regions and are thus covered by glaciers.
e. Those rocks have been deposited in oceanic trenches deep in the oceans.
a
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Plants do not grow well in soils with a lot of clay
because these soils a. hold onto and do not release water easily. b. are deficient in plant micronutrients and macronutrients. c. tend to absorb too much surface water. d. tend to become compacted and exclude air. e. do none of these.
Assume that several members of a particular species of mosquito inadvertently entered an airplane in Asia and were transported to the United States, where they thrived as an isolated colony. What is likely to occur over time?
a. The isolated species will breed with closely related species in the United States, forming a new species. b. The species undergo sympatric speciation. c. The colony could genetically diverge in isolation and a new species could be formed. d. Genetic divergence of the population would eventually cease. e. Isolation would encourage extinction.
Suppose a scientist working on a new drug for cancer developed a chemical that irreversibly breaks the hydrogen bonds in the DNA molecules within cancerous cells but leaves all of the covalent bonds intact
Hydrogen bonds are relatively weak compared to covalent bonds, and they are routinely broken and reformed as the DNA molecule is replicated in a normal cell. Their stability is nonetheless critical for maintaining certain aspects of the structure and function of the DNA molecule. Based on this scenario and your knowledge of DNA, how would this newly discovered chemical affect the "molecule of heredity" in a human cancer cell? A) It would break the individual strands of the DNA molecule apart, preventing it from functioning normally. B) It would result in constant DNA replication within the cell. C) It would break the two strands of the DNA molecule apart, preventing it from functioning normally. D) It would allow the DNA molecule to function normally except during replication.
_____ is a liquid tissue and is a subtype of _____ tissue
Cartilage; dense connective Smooth muscle; loose connective Blood; specialized connective Blood; proper connective