In african savannas elephants are a keystone species. elephants eat small trees, such as acacia, that grow on the savanna. even if an acacia tree grows to a height of several feet, elephants are able to knock over the tree and uproot it. imagine a drastic decline the elephant population that live within the african savannas. what would be the inevitable result? a) the savanna would decline and evolve into a desert ecosystem. b) predators would replace the elephants as the keystone species. c) another large herbivore would immigrate and replace the elephant. d) the savanna would succumb to succession and evolve into a woodland.

The tasmanian devil, a marsupial carnivore, is facing extinction due to devil facial tumor disease (dftd) which causes bulging cancerous lumps and lesions to erupt around the face and neck — often causing enough deformation to make seeing or eating difficult. dftd has evolved into a contagious cancer, a trait that is unique among cancers. devil mating behavior involves biting around the head and neck, allowing cells from one individual — especially cells from the crumbly dftd tumors — to be transferred to the wounds or face of a new individual. this marsupial was once found across australia, but sea levels rose, isolating the tasmanian population, while the australian population went extinct. what would be an outcome of genetic isolation that is likely to have impacted the spread of dftd? a) reduced territory puts diseased individuals in greater contact with non-diseased ones. b) inbreeding results in less variation in facial features so the cancer is generally fatal. c) genetic isolation has made it difficult for scientists to develop a vaccine against dftd. d) the lack of genetic variation in the immune system of tasmanian devils minimizes resistance to the disease.

Which part of cellular respiration must occur before any of the other steps can occur

Which direction does the energy flow in this energy pyramid ?