2.In a dihybrid cross, there are nine (9) different kinds of genotypes in the
F2offspring. how many different kinds of phenotypes will beobserved?
A. 2
B. 4
C. 6
D. 8
3. Suppose you have two lines of flies, which are homozygous for two different traits.
However, you don't know the mode of inheritance for the genes you are testing. What
will be your first clue?
A. The genotypes of the parents.
B. The phenotypes of the parents.
C. The genotypes of the dihybrids.
D. The phenotypes of the dihybrids.
4. Imagine that a couple is planning to have children. The male is heterozygous for
tongue rolling and homozygous dominant for unattached earlobes. The female is
homozygous recessive for tongue rolling and heterozygous for unattached earlobes. The
couple is curious about the possibility and probability of their offspring inheriting these
traits. The ability to roll one's tongue is dominant (R) over the "non-rolling" condition
(r.) Unattached earlobes (U) are dominant over attached earlobes (u) Complete a
Punnett square for this cross and record the probabilities for genotypes and phenotypes
of the offspring as ratios. Which of the following is correct about the possible genotypes
of the children?
A.9 RrUU, 3 RrUu, 3 rrUU, and 1 rruu
B.8 RrUU, 3 RrUu, 3 rrUU, and 2 rrUu
C.6 RrUU, 4 RrUu, 3 rrUU, and 3 rrUu
D.4 RrUU, 4 RrUu, 4 rrUU, and 4 rrUu
5. The dominance relationship between alleles for each trait was already known to
Mendel when he made this cross. What is the purpose of Dihybrid cross?
A. To determine the dominance relationship between two alleles.
B. To determine if any relationship existed between different allelic pairs.
C. To determine the probability of an offspring expressing a particular genotype.
D. To determine the genotype of an unknown plant and to produce "true-
breeding" offspring.
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Answer:
2. A
3. C
4.D
5. B
Explanation: Correct if I'm wrong but, that's my answer.