Aa. Aa. AA. Zebra mussels have the following genotypes and phenotypes. Which cross would produce the greatest number of heterozygous. A) AA x aa. B) Aa x Aa. C) AA x AA. D) as x Aa

A (AA x aa)

Explanation:

In option (A) both of the parent mussels are homozygotes, for alleles "a" and "A" respectively. Therefore, every single one (100%) of their offspring would be expected to be Aa heterozygotes. Combinations (B) and (D) yield a lower proportion of heterozygotes (50%), and combination (C) yields none at all. Punnett squares follow:

(A)

  |  A      A        

a |  aA    aA      

a |  aA    aA      

(B)

  |  A      a      

A |  AA   Aa    

a |  aA    aa      

(C)

  |   A      A        

A |  AA    AA    

A |  AA    AA    

(D)

  |  A      a        

a |  aA    aa      

a |  aA    aa      

option a and d is the correct answer

i hope this u

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the level of progesterone is low at the pre-ovulatory phase of the cycle but it gradually increases and the levels are high at the luteal phase. if pregnancy occurs, the level of progesterone will be high throughout the pregnancy.

if egg is fertilized and the mother gets pregnant, progesterone starts preparing the uterus for the implantation. it starts building up the lining of uterus and make it hostile of the period of pregnancy.