Which of the following statements is NOT true?
a. There is always a gradient of sucrose
concentration from source to sink.
b. Sucrose is generated at the source and converted
or used at the sink.
c. Companion cells help load the phloem sieve
tubes.
d. Sieve tubes are only passive conduits for
translocation.
e. The active transport of water into the sieve tubes
produces the pressure for the translocation of
organic compounds in the phloem.
Answer: e
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What will be an ideal response?
As a consequence of the immune system in humans recognizing dsRNA as foreign,
A) dsRNA viruses rarely infect humans. B) dsRNA viruses quickly transcribe their genes into mRNA which is insensitive to immune responses. C) genomes of RNA viruses are often chemically modified to avoid recognition by human immune cells. D) the genomes of dsRNA viruses must avoid human immune cells during infection, including replicating their genomes within their own nucleocapsids.
Bioassays can be used to
(a) test new drugs. (b) determine the effectiveness of new fertilizers and herbicides. (c) measure the effects their waste discharges have on aquatic organisms. (d) do all of these choices.
What would a female genotype have to be for her to have the genetic disease hemophilia?
a. Both her X and her Y chromosome would have to have the recessive hemophilia gene. b. Only one of her X chromosomes would have to have the hemophilia gene. c. Both her X chromosomes would have to have the recessive hemophilia gene. d. Both her Y chromosomes would have to have the recessive hemophilia gene.