Mice engineered to express both ras and myc constitutively in mammary epithelial cells
a. developed breast cancer soon after birth, because the combination of ras and myc is sufficient to cause cancer in animals
b. were indistinguishable from wild type mice
c. developed breast cancer, but only after a lag during which p53 was also lost
d. developed breast cancer, but only when they reached sexual maturit

Which of the following is a difference between a food chain and a food web? selected: a. food webs contain both plants and animals. food chains only contain animals. this answer is incorrect. b. food webs show energy transfer. food chains show which animal eats which animal. c. food webs separate organisms by tropic level. food chains do not. d. food webs are a complex patterns of energy flow. food chains only show one line of energy flow.

What came first egg or chicken? and is tomato a vegetable or a fruit?

Which muscle is responsible for inhalation ?