What is the main factor contributing to the current human-caused mass extinction?
a. increased population growth
b. burning of fossil fuels
c. the industrial revolution
d. global-warming
e. decreased population growth
ANSWER: a
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In a(n) _____, atoms share an electron unequally
1.non-polar bond 2.ionic bond 3.polar covalent bond 4.covalent bond
Which feature possessed by most land plants is missing in mosses, which grow low to the ground in damp, shaded areas?
a) chlorophyll b, so they can only use filtered light for photosynthesis b) starch production, so they only produce small amounts of glucose, since any beyond what they use immediately cannot be stored c) cell walls, so they cannot stand upright d) a protected zygote, so they must grow in damp areas to supply the zygote with moisture e) vascular tissue, so they must grow along the ground in damp areas to supply water to the cells
Which of the following occurs in prophase??
a. sister chromatids attach
b. DNA replicates
c. chromosomes align in the middle of the cell
d. the nuclear envelope breaks down
e. sister chromatids separate
Which of the following describes a prezygotic barrier that could contribute to reproductive isolation?
a. A male moth lacks the specific sensory receptors for a pheromone produced by a female moth. b. Two grass varieties possess different mutant recessive alleles and offspring resulting from backcrossing with hybrids express more detrimental recessive traits. c. The offspring of crosses between lions and tigers cannot produce offspring themselves. d. Different salamander subspecies of a single genus produce offspring with each other, but these have shorter life spans than offspring of two parents within the same subspecies. e. None of the listed responses describe a postzygotic barrier.