In the pressure-flow model of phloem transport, the sink is normally
A. the stem.
B. lenticels.
C. xylem.
D. the roots.
Answer: D
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A trait caused by an environmental influence that appears to be inherited is
A) pleiotropic. B) a phenocopy. C) incompletely penetrant. D) multigenic.
Answer the following statements true (T) or false (F)
1) Two genes are considered linked when there are more F2 progeny with recombinant genotypes than parental genotypes in the offspring of a dihybrid testcross. 2) Chiasmata are structures that show where recombination occurred between sister chromatids. 3) Chiasmata can be seen through a light microscope and are sites of recombination. 4) A linkage group includes all of the genes on a chromosome, including genes that are so far apart from each other on a chromosome that they assort independently during meiosis. 5) The hypothesis that predicts no linkage between genes is known as the null hypothesis.
Pollen preserved within lake sediments can be used to reconstruct historical changes in the geographic ranges of plant species
Indicate whether the statement is true or false
Choose the incorrect statement regarding adaptation from the following:
A) Some observed traits may not be adaptive, but are simply due to the process of genetic drift. B) Although adaptations may seem to exist for obvious reasons, their presence always needs to be tested. C) All traits that are observed are not necessarily adaptive. D) If a trait is adaptive, it will perfectly fit a need that confers an evolutionary advantage. E) At the molecular level, many of the variations among individuals, populations, and species may be selectively neutral.