Biology Forums - Study Force

1. Mendel's Law of Independent Assortment states that

Select one:
a. nonallelic genes are independent if found on separate chromosomes
b. chromosomes are the carriers of genes that do not separate to form gametes
c. a blending of traits occurs when genes are found on separate chromosomes
d. allelic genes tend to mix, resulting in incomplete dominance

2. In garden peas, the allele for tall pea plant height (T) is dominant over the allele for short plant height (t) and the allele for round seed shape (R) is dominant ove the allele for wrinkled seed shape (r). The genes for these traits assort independently.


Consider the cross: Plant I (tall - wrinkled ) x  Plant II (tall - round seeds). Which row identifies correctly the gametes that might be produced by these plants?

Plant I                                    Plant II
A. Tr or tr only            A. TR, Tr, tR, or tr
B. TR, tr, tR, or tr            B. TR, Tr, tR, tr
C. Tr or tr only            C. TR or tr only
D. TR, Tr, tR, tr            D. TR, or tr only

3. In Drosophila, ebony body colour is caused by the recessive allele eb and grey body colour by the dominant allele eb+. Vestigal wings are produced by the recessive allele vg and long wings by the dominant allele vg+.

When mated a female with ebony body colour and vestigal wings produced the following offspring:
41 flies with ebony body and long wings
44 flies with grey body and long wings
39 flies with grey body and vestigal wings
46 flies with ebony body and vestifal wings

What was the genotype of the male parent in this cross?

a. eb+eb  vg+vg+
b. eb+eb  vgvg
c. eb+eb  vg+vg
d. eb+eb+  vg+vg+

3a. Using the information from the previous question, how many of the 44 offspring with grey bodies and long wings can be expected to be heterozygous for body colour?

a. 11
b. 22
c. 44
d. 33

4. The following is a hypothetical condition that occurs in some cats. Two alleles S and s, determine whether the cat's coat is a vertically striped (S) pattern or a horizontal striped (s) pattern. Vertically striped (S) pattern is dominant. A second pair of alleles T and t, are located on a pair of chromosomes separate from S and s. The homozygous recessive genotype tt, prevents the expression of either the S allele or the s allele and produces a cat with no stripes but with a solid black coat.

Some examples of genotypes and phenotypes for these particular cats are:
SSTt: vertical striped pattern shows
ssTt: horizontal striped pattern shows
Sstt: no striping shows; a solid black coat results
  
Two cats, each with the genotype SsTt, were crossed. What is the percentage probability that their offspring would have solid black coats?

5. What chance would a family have of producing three boys in succession?

a. 1/8
b. 1/2
c. 3/4
d. 1/4

6. Two different genes control the expression of coat colour in an organism. The allele B produces a black coat colour and the allele G produces a gray-striped coat. The gene B influences the expression of gene G. The gray-stripped coat pattern appears only when gene B is homozygous recessive. An albino (coat colour lacking) occurs when both genes are homozygous recessive.

A pure-breeding black coated organism was mated with an albino organism; all offspring had black coats.

The genotypes of the parents of these F1 offspring could be

Select one:
a. BbGG  x  bbgg
b. BBGG  x  bbgg
c. Bbgg  x  bbGG
d. bbGG  x  BBgg

7. The following is a hypothetical condition that occurs in some cats. Two alleles S and s, determine whether the cat's coat is a vertically striped (S) pattern or a horizontal striped (s) pattern. Vertically striped (S) pattern is dominant. A second pair of alleles T and t, are located on a pair of chromosomes separate from S and s. The homozygous recessive genotype tt, prevents the expression of either the S allele or the s allele and produces a cat with no stripes but with a solid black coat.

Some examples of genotypes and phenotypes for these particular cats are:
SSTt: vertical striped pattern shows
ssTt: horizontal striped pattern shows
Sstt: no striping shows; a solid black coat results
  
Two cats, each with the genotype SsTt, were crossed. What is the percentage probability that their offspring would have solid black coats?

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Thanks a whole bunch! I still need help with number 2.

thanks!

thank you

thank you