Birds migrate great distances each year and the primary cue for migration are changes in day length. these changes in day length in turn trigger changes in the birds. behavior and body changes follow as the birds prepare for their seasonal migrations.
a) genetic
b) hormonal
c) physical
d) reproductive

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

d. planting trees

the trees take in carbon to make oxygen.

we need additional information in order to determine the cause of death for anna garcia. there are at least 3 things with explanation included as to why we need them are as follows: