Why is fertilization in flowering plants called double fertilization?
a. it takes two pollen grains to fertilize a single ovule
b. two ovules must be fertilized to form a single seed
c. two cells in the ovule are fertilized, the egg and the endosperm mother cell
d. one pollen grain fertilizes two ovules
e. it takes the efforts of two flowers (male and female) to produce seeds
ANSWER: c
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Dendrochronology can be useful in determining:a
the dates of past earthquakes and volcanic eruptions. b. future climate patterns. c. the solution to global warming. d. how tree growth affects air pollution. e. the time of day.
For which of the following reasons does nucleotide excision occur?
a. to repair thymine dimers b. to replace proteins c. to correct a faulty base d. to form a replication fork
In Drosophila, assume that the gene for scute bristles (s) is located at map position 0.0 and that the gene for ruby eyes (r) is at position 15.0. Both genes are located on the X chromosome and are recessive to their wild-type alleles
A cross is made between scute-bristled females and ruby-eyed males. Phenotypically wild-type F1 females were then mated to homozygous double mutant males, and 1000 offspring were produced. Give the phenotypes and frequencies expected.