Nondisjunction is the failure of chromosones to seperate correctly during cell division. Nondisjucntion during meiosis violates Mendels Law of Segregation, producing gametes with an incorrect number of chromosones. The two types of nondisjunction during meiosis in females are shown in the image. The genetic contents of the zygotes that would result from the fertilization of each egg by a sperm are also shown.

For an organism with a haploid number of n=8, what percentage of the gametes resulting from a nondisjunction event of one chromosone pair during meiosis 1 will have only seven chromosones?

A: 25%
B: 50%
C: 75%
D: 0%

Refer to this portion of a dichotomous key for fish identification to answer the question. 1. (a) has a single dorsal fin ® 5 (b) has a double dorsal fin ® 2 2. (a) one fin is spiny, the other is smooth ® 3 (b) one fin is not spiny or smooth ® 4 5. (a) has small fin on back near tail ® 6 (b) has no fin on back near tail ® 7 6. (a) has barbs near the mouth ® catfish (b) does not have barbs near the mouth ® 10 7. (a) tail is asymmetrical ® 8 (b) tail is symmetrical ® 9 10. (a) scales are small ® trout (b) scales are large ® whitefish what is the next step to complete to identify a fish that has a single dorsal fin, no fin on the back near the tail, and no barbs near the mouth? step 2 step 5 step 7 step 10