What is a seed?
A. a mature pollen
B. a diploid embryo
C. a mature sporophyte
D. a diploid spore
E. a haploid gametophyte
B. a diploid embryo
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Many songbirds breed in North America in the spring and summer and then migrate to Central and South America in the fall. They spend the winter in these warmer areas, where they feed and prepare for the spring migration north and another breeding season
Two hypothetical species of sparrow, A and B, overwinter together in mixed flocks in Costa Rica. In spring, species A goes to the east coast of North America, and species B goes to the west coast. What can you say about the isolating mechanisms of these two species? A) They must have strong postzygotic isolating mechanisms to spend winter in such close proximity. B) They must have strong prezygotic isolating mechanisms to spend winter in such close proximity. C) Their winter habitat has no bearing on their degree of reproductive isolation. D) Reinforcement must be occurring when they winter together.
An chemical reaction that requires an input of energy in order to proceed is ________.
A. endergonic B. impossible C. exergonic D. None of the choices are correct.
Answer questions 120–124 in reference to the five items listed
below. a. 12 b. 23 c. 24 d. 46 e. 47 D 120. How many chromosomes does each somatic cell have in a human male who has two X chromosomes? D 121. Following a gene duplication event involving only five loci, how many chromosomes will a human female have? D 122. How many chromosomes are present in the somatic cells of a child born with Down syndrome (trisomy 21)? D 123. How many chromosomes are present in each cell of the germ cell line for a tetraploid species where its normal complement of chromosomes is 48? D 124. The normal sperm cell of species X carries 11 chromosomes. Following nondisjunction in the formation of secondary spermatocytes and their subsequent fertilization of normal ova, some of the zygotes will have 21 chromosomes, others will have 22, and the remainder will have how many chromosomes?
Brushlike projections from the villi are
a. cilia. b. flagella. c. lymph vessels. d. microvilli. e. rugae.