Las vacuolas contráctiles se encuentran en protozoarios ciliados marinos y de agua dulce, esponjas. Estos se llenan de un fluido claro hasta cierto volumen y luego es expulsado al interior de la celula.

Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human x chromosome. the patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. they rarely live past their twenties. how likely is it for a woman to have this condition? a) women can never have this condition. b) one-fourth of the daughters of an affected man would have this condition. c) one-half of the daughters of an affected father and a carrier mother could have this condition. d) only if a woman is xxx could she have this condition.

Aparent with freckles is crossed with a parent without freckles. the punnett square shows the possible genotypes and phenotypes of the offspring. which statement accurately describes the probability of phenotypes? a. the offspring are more likely to have freckles. b. the offspring are more likely to have no freckles. c. the likelihood of the offspring having freckles and not having freckles is the same. d. the likelihood of the offspring having freckles and not having freckles cannot be determined.

Which of the following must be true for a fossil organism to be useful as an index fossil? a. the fossil organism must be widespread geographically. b. the fossil organism must be abundant. c. the fossil organism must be limited to a short span of geologic time. d. all of the above.