The IRT1 gene is responsible for most of the iron uptake activity in roots (Vert et al., Plant Cell 14 [2002]:1223—33)
To determine the specificity of the IRT1 transporter in Arabidopsis plants, researchers measured the concentration of manganese, zinc, copper, and cobalt contained in wild-type and irt1-1 mutant plants. What conclusions about IRT1 specificity can you draw from the above data?
A) Under iron-deficient conditions, IRT1 is highly specific for iron.
B) Under iron-deficient conditions, IRT1 is important for the transport of iron and copper.
C) IRT1 is important for the transport of iron and copper independent of iron concentration.
D) Under iron-deficient conditions, IRT1 is necessary for the transport of iron, zinc, manganese, and cobalt.
E) IRT1 participates in the transport of iron, zinc, manganese, and cobalt independent of iron concentration.
Answer: D
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The frequency of recombination during meiosis is a function of:
A. the alleles on the genes; recombination happens less frequently among recessive alleles. B. the distance between genes: the closer the genes are, the more frequent the recombination between them. C. the distance between genes: the farther apart the genes are, the more frequent the recombination between them. D. whether or not the genes are sex-linked; X chromosomes recombine much more frequently than do autosomes. E. whether or not the genes are sex-linked; Y chromosomes recombine much more frequently than do the autosomes.
What is the general global pattern of species richness?
A. Increasing from east to west across continental land masses. B. Increasing from polar areas towards the tropics. C. Increasing from tropical seas into temperate forests. D. Increasing from the tropics towards polar areas. E. Increasing from clay soil types into organic soils.
__________ is a concentration of nerves and sensory structures at the head end. Fill in the blank(s) with the appropriate word(s)
This type of mechanoreceptor is found in the lips, nipples, and fingertips and helps us to precisely determine contact with something else
A) free nerve endings B) Pacinian corpuscles C) Meissner's corpuscles D) hair root plexus