Of the following, which is an example of a postzygotic barrier? O Due to incompatible interactions between inherited genes, a hybrid fetus is unable to develop, and is aborted. O One species mates in spring, while another mates in summer. O A female spider of one species does not respond to the mating display of a male of a closely related species. Cell surface proteins of one species eggs prevent sperm from another species attaching, so the sperm cannot fertilize it.

Which reproductive barrier is most likely to prevent interbreeding between a polyploid species and its diploid sister species? Behavioral isolation: the two species will not recognize each other as mates O Gametic isolation: sperm and egg with different chromosome numbers cannot complete fertilization Hybrid infertility: differences in chromosome numbers will result in infertile hybrids O Mechanical isolation: differences in reproductive structures will prevent interbreeding O Temporal isolation: the two species will not reproduce at the same time of year

Scientists have also noticed unusual coloration among certain condor populations. Andean condors are typically black in color.  However, a few unique white feathered individuals have occasionally been noted. These white feathered individuals are not well-camouflaged, and are easily spotted by larger predators.  Recently, scientists noted that a black feathered condor had mated with a white-feathered condor, and their three chicks all appeared to have gray feathers. Closer examination of these condor chicks revealed that the chicks actually possessed a mixture of black feathers and white feathers, giving them a gray appearance from a distance. Please NAME and EXPLAIN the genetic phenomenon described here.

In humans, mammals and many other chordates sexual reproduction takes place by fusion of large immobile ovum and small motile sperm. This kind of sexual reproduction is: Select one: a. Isogamy b. Schizogony c. Oogamy d. Conjugation e. Polyteny

The Oregon creeping vole, Microtus oregoni, has a very unusual meiosis?. In this rodent, males are XY, while females are XØ (that is, females have only a single X chromosome). During female meiosis, eggs that receive no maternal X chromosome do not mature, so females only produce eggs with exactly one X chromosome. As chromosome content is unchanged from generation to generation, M. oregoni males (who are XY) must deliberately nondisjoin their sex chromosomes. 1a) What types of sperm would M. oregoni have to produce (considering only their sex chromosome content) so that progeny get the right chromosomes? Remember, no inviable combinations are normally produced. 1b) Draw a Punnett square for the sex chromosomes in a M. oregoni mating, with the gametes that are actually produced. Indicate the sex of each offspring. 1c) From which parent do M. oregoni get their X chromosomes? Circle one. Mom Only Random Mom or Dad Dad Only