In cats the hair can be either short or long (angora). A cat fancier made the fo

Question

In cats the hair can be either short or long (angora). A cat fancier made the following crosses.

                  PARENTS                                           KITTENS

      (1) angora X angora                              all angora

      (2) angora X short                                all short

      (3) short X angora                                4 short, 5 angora

      a. Which phenotype is dominant? (S) Short

      b. What are the genotypes of the parents and offspring of these crosses?

      c. If the short-haired offspring from cross 3 were bred to their short parent, what kinds of kittens would be expected and in what proportions?

      d. If the short-haired offspring from cross 3 were bred to the short-haired parent of cross 2, what kinds of kittens would be expected and in what proportions?

Explanation / Answer

A. short is the dominant phenotype because angora X short produced all short. In order for a cross between two different phenotypes to produce all of one phenotype, that resulting phenotype has to be the dominant trait.

B. (i) angora X angora   - all angora`s                         (ii)     angora X short   - all short

    (ss)     X (ss)          - (ss)                                              (ss)   X (SS) - (ss)

          (iii) short X angora   - 4 short, 5 angora

                  (Ss) X (ss)      - (Ss)50% short, (ss)50 % angora.

C. short offspring (Ss) X (Ss)

    gives Ss,    SS, ss,    ss = 25% short, 25% heterozygous short, 50% angora.

D. Cross 3 short offspring "Ss"X Cross 2 short parent = "SS". Punnett square gives 50% SS (homozygous dominant) short, and 50% Ss (heterozygous) short.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.