Many human skin tumors contain mutated p53 genes that probably result from excess UV exposure. One of 10 different equally likely mutations of the p53 gene always results from a single episode of excessive UV exposure; the 10 mutations remain equally likely over repeated exposures. A p53 gene must experience all 10 mutations before a tumor can develop. Assume that only one mutation can occur as a result of one excessive UV skin exposure. Question 2. How many excessive UV exposures would you expect are required until the p53 gene has experienced all 10 mutations

Elements and compounds are pure substances that cannot be broken down physically into a simpler substance. a physical change doesn’t break the bonds between atoms of a substance or form new ones. compounds can be broken down by a chemical change. a chemical change breaks chemical bonds and/or forms new ones between atoms of a substance. what simple substance would a compound break into? the basic elements that make it up! for example, if you passed a very strong electric current through water you’d break the chemical bonds in water and be left with oxygen and hydrogen. which of the following is an example of a chemical change? a separating water into different glasses b breaking frozen ice cubes with a hammer c running an electric current through water d boiling water to evaporate it on a stove

!if we removed the wolf, snake, and hawk from this food web, what best explains the impact it would have? a) the number of producers would increase. b)the number of decomposers would increase. c)the number of primary consumers would increase. d)the numbers of primary consumers would decrease.

Which organisms have pharyngeal arches that develop from all three germ layers and go through the same development stages as embryos? 1.bird 2.ladybug 3.starfish 4.snake