The following options are all reproductive barriers. which one is an example of a prezygotic barrier in which the two different species do mate?
1 two crayfish species cannot interbreed because their genitalia do not engage properly with each other.
2 hybrid mules produced by mating donkeys and horses are sterile.
3 one bird species lives in wetlands, the other in dry forests; hence, they do not encounter each other.
4 two dragonfly species regularly mate, but their gametes are incompatible.

Salmonella typhimurium is a food-borne bacterial pathogen that can cause severe gastrointestinal disease. salmonella is often phagocytosed by macrophages that normally destroy bacterial pathogens, but this bacterium is somehow able to prevent the complete maturation of phagolysosomes. salmonella is able to tolerate the low ph of phagolysosomes, and in fact responds to the drop in ph by secreting toxins that interfere with other cellular responses. which of the following differences would you expect to contribute to the survival of a bacterium within an salmonella-containing phagosome, compared to a healthy phagolysosome? decreased activity of acid hydrolases increased activity of acid hydrolases decreased import of h+ ions increased import of h+ ions my guess is decreased activity of acid hydrolases but i'm not sure.

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above

Which organelle plays a role in intracellular digestion?