BIOLOGY - 9.11 - 9.16

Question 1

Why doesn’t the cross shown in Figure 9.11A support the blending hypothesis?

Answer 1

Although two of the F2 offspring show a “blended” phenotype (pink flowers), the other two do not, and the white and red alleles are not lost to future generations.

Question 2

Maria has type O blood, and her sister has type AB blood. The girls know that both of their maternal grandparents are type A. What are the genotypes of the girls’ parents?

Answer 2

Their mother is I^Ai; their father is I^Bi.

Question 3

Why is the sickle-cell trait considered codominant at the molecular level?

Answer 3

Codominance means that both traits are expressed; a carrier for the sickle-cell allele produces both normal and abnormal hemoglobin.

Question 4

An AaBbcc individual would be indistinguishable in phenotype from which of the following individuals: AAbbcc, aaBBcc, AabbCc, Aabbcc, or aaBbCc?

Answer 4

All except Aabbcc

Question 5

Which of Mendel’s laws have their physical basis in the following phases of meiosis: (a) the orientation of homologous chromosome pairs in metaphase I; (b) the separation of homologous chromosomes in anaphase I?

Answer 5

(a) The law of independent assortment; (b) the law of segregation