According to the pressure flow theory, sugars move in phloem because of ________
a. negative pressure from removal of sugars at sinks
b. active transport by living sieve-tube and companion cells
c. all of the choices
d. internal pressure building up in sieve tubes at a source
d
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Resonance:
A. is an aspect of valence bond theory that describes the multiple structures that can be adopted by a single bond. B. occurs in molecules that contain single and double bonds next to each other and, as a result, can exist as an average of multiple structures. C. explains why double bonds are planar. D. is an aspect of valence bond theory that describes the multiple structures that can be adopted by a double bond. E. occurs in peptide bonds but not in nucleic acids.
Creation of a special, resistant zygospore during sexual reproduction is characteristic of members of
which fungal phylum?
a. Glomeromycota b. Basidiomycota c. Chytridiomycota d. Zygomycota e. Ascomycota
Earthworms exhibit segmentation, defined as the
a. division of the body into a series of similar segments. b. presence of a true coelom. c. difference in size of the male and female. d. presence of a "head" equipped with sensory organs.
Due to global warming what occurred in fish in the North and Celtic seas?
A) Species richness increased. B) Species richness declined. C) Fewer deep-water species were present. D) Fewer shallow-water species were present.