Inheritance/cross question?

Question

In which kind of cross would you expect to find exactly the anticipated ratios every time the cross is made?

a. monohybrid cross

b. dihybrid cross

c. test cross

d. none of the choices are correct.

Is it a???? Maybe d.

Answer 1

the wording is a bit strange

because if you cross Bb*Bb a monohybrid cross, the resulting
ratios of effects should be what is expected every time...

BB Bb Bb bb

In a dyhibrid cross BbRr*BbRr for two traits, the actual ratios should be the same as predicted!!

A test cross is used for something else.

SO, it appears the answer is D.

Since both A and B should result in the same ratios as expected

the answer is probably trying to get at the fact that to be absolutely sure, you need homogeny, like BB*BB

This way if two dominant Brown Eyes cross, the kids will ALWAYS have brown eyes!!!!

If we take two Brown eyed people who are Bb

Bb*Bb... the expected ratios are BB 25% Bb 50% bb 25%
However, if you have 4 kids, in actual fact all 4 kids MAY have blue eyes!! Therefore what actually happens may be different from what the statistics predicts

Answer 2

The anticipated ratios are just that, expected or anticipated. The key word in the question is "exactly." You will usually only approach those numbers (and rarely if ever) actually see those numbers, if you are doing any type of hybrid cross. The only time you will see exactly the expected ratios in each cross will be when you cross homozygotes and even then, only if some genetic aberration (like a mutation) does not occur. So, you are correct, the answer is d.

Answer 3

Unless you are dealing with VERY large numbers the answer is D. Just as a coin can come up heads 2 or 3 times in a row - the anticipated ratio is rarly followed exactly because each inhertance is random chance distrubution of genes.
My parents SHOULD have had half their children blue eyed they had 3 brown eyed kids.

Answer 4

May be option d. Got 2 points... thanks