The phrase "double fertilization" in angiosperms is best described by which of the choices below?
a. Two pollen grains land on the same stigma.
b. Each pollen grain contains two sperm cells; one leads to the fertilization that produces the embryo and the other leads to the fertilization that produces the endosperm.
c. Each angiosperm is fertilized twice during a particular mating season and produces two offspring.
d. Two sperm cells fertilize the same egg cell that leads to the embryo.
e. Each pollen grain contains two sperm cells and each fertilizes its own egg.
Ans: b. Each pollen grain contains two sperm cells; one leads to the fertilization that produces the embryo and the other leads to the fertilization that produces the endosperm.
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Indicate whether the statement is true or false.
Which of the following statements about sister chromatids is TRUE? rev:
A. Sister chromatids are produced during mitosis. B. Sister chromatids are held together by complementary base pairing of DNA at the centromere. C. Sister chromatids are exact copies of each other and are formed just prior to cell division. D. After mitosis, sister chromatids contain the same genes, but they may have different alleles. E. All of these statements about sister chromatids are TRUE.
Which statement about genomics is false?
A) The first complete genome to be sequenced was a prokaryote. B) Whole sets of genes and their interactions are studied in the field of genomics. C) Genes from different species that have analogous sequences suggest similar function. D) DNA technology limits genomic studies to prokaryotes.
In some ciliate protozoa, the codons UAA and UAG encode glutamate, rather than acting as stop codons. How does this compare to other species?
A. This is not unusual-while most species have a similar genetic code, there are often variations for some of the amino acids. B. This is unusual-almost all species share the same universal genetic code. C. This is typical-every species has its own unique genetic code.