A cline is:
a. a temporal gradient in the frequency of genotypes and phenotypes.
b. a spatial gradient in the frequency of genotypes and phenotypes.
c. an area of resource competition.
d. an area of assortative mating.
B
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The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of ?-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that _____.
A) the Radiata should be a true clade B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait C) Hox genes play little actual role in coding for an animal's "body plan" D) the Cnidaria may someday replace porifera as the basal bilaterians B) the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral
Which cell organelle functions to transport materials from the endoplasmic reticulum throughout the cell?
a) ribosome b) Golgi apparatus c) lysosome d) vacuole
Which group(s) of plants requires water in order for the sperm cell to swim to the egg?
a) seed plants b) only ferns c) only mosses d) both mosses and ferns e) all plants
Using genetic engineering techniques, you remove the sequences that code for the ribosome-binding sequences of the bacterial LacZ gene. The removal of these sequences will lead to ___________
(a) more LacZ protein produced due to faster ribosome movement across the LacZ mRNA. (b) transcriptional repression, resulting in fewer mRNA molecules produced from this gene. (c) a longer half-life for the LacZ mRNA. (d) translational inhibition of the LacZ mRNA.