In order for a male to express a recessive sex-linked trait that is located on x chromosomes, he must have:

an additional recessive allele on his y chromosome

two recessive autosomal alleles

an inactive allele

one recessive allele on his x chromosome
!

Which conditions are necessary for natural selection to occur? select all of the answers that apply. a. inheritable adaptations vary among individuals. b. the population size is increasing. c. more individuals are born than can survive. d. fitness varies among individuals. e. the environment changes suddenly and drastically.

How does deforestation affect the water cycle? a. it increases the amount of runoff b.it increases the amount of percolation c. it increases the amount of transpiration d. it increases the amount of precipitationa it increases the amount of runoff

Which of these substances does not protect against invaders in the nonspecific immune response? a. saliva b. mucus c. tears d. urine