Biology2
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- 1.When looking at the inheritance of a single characteristic, Mendel found that a cross between two true-breeding peas (between purple and white, for example) always yielded a ______ in the F2 generation.
- A.
3:1 phenotypic ratio
- B.
1:1 genotypic ratio
- C.
3:1 genotypic ratio
- D.
1:2:1 phenotypic ratio
- 2.A fruit fly has two genes for eye color, but each of its sperm cells has only one. This illustrates
- A.
Independent assortment.
- B.
Segregation.
- C.
Polygenic inheritance.
- D.
Pleiotropy.
- 3.Mendel made some crosses where he looked at two characteristics at once-round yellow peas crossed with wrinkled green peas, for example. He did this because he wanted to find out
- A.
Whether the characteristics influence each other-whether color affects degree of roundness, for example.
- B.
Actually, Mendel never had a clear purpose in mind.
- C.
How new characteristics originated.
- D.
Whether different characteristics were inherited together or separately.
- 4.When an individual has both IA and IB blood group alleles, both genes are expressed and the individual has group AB blood. This is an example of
- A.
a dihybrid.
- B.
Codominance.
- C.
Pleiotropy.
- D.
Incomplete dominance.
- 5.The sex chromosomes of a human female are ____. The sex chromosomes of a human male are ____.
- A.
XY . . . XX
- B.
XX . . . XY
- C.
YY . . . XY
- D.
XX . . . YY
- 6.Most sex-linked traits in humans are carried on the ____ chromosome, and the recessive phenotypes are seen most often in ____.
- A.
X . . . men
- B.
Y . . . men
- C.
X . . . women
- D.
Y . . . women
- 7.Which of the following human genetic disorders is sex linked?
- A.
PKU
- B.
Hemophilia
- C.
Cystic fibrosis
- D.
Sickle-cell disease
- 8.Assume that brown color is dominant over white color in mice. Suppose you wanted to know the genotype of a brown mouse. The easiest way to do it would be to:
- A.
Mate it with a white mouse.
- B.
mate it with a mouse of its own genotype.
- C.
Mate it with a brown mouse.
- D.
It can't be done.
- 9.Which of the following illustrates pleiotropy?
- A.
In fruit flies, the genes for scarlet eyes and hairy body are located on the same chromosome.
- B.
Wheat kernels can range from white to red in color, a trait controlled by several genes.
- C.
Matings between earless sheep and long-eared sheep always result in short-eared offspring.
- D.
The human cystic fibrosis gene causes many symptoms, from respiratory distress to digestive problems.
- 10.In fruit flies, the allele for red eyes is dominant, and the allele for purple eyes is recessive. Normal gray body is dominant, and black body is recessive. A geneticist mated a heterozygous red-gray male with a purple-black female. She predicted that there would be four phenotypes of offspring in equal numbers, but she was wrong. Instead, 48% of the offspring were red-gray, 46% were purple-black, 3% were red-black, and 3% were purple-gray. She concluded that in the male, the red and gray genes were linked, and in the female the purple and black genes were linked. If this is the case, how would you account for the red-black and purple-gray offspring?
- A.
Segregation of alleles occurred during meiosis.
- B.
Body color and eye color are quantitative characteristics.
- C.
This is an example of pleiotropy
- D.
This cross shows incomplete dominance at work.
- 11.On a pedigree tracing the inheritance of PKU, a horizontal line joins a black square and a half-black circle. What fraction of this couple's children would you expect to suffer from PKU?
- A.
1/2
- B.
1/4
- C.
3/4
- D.
none
- 12.Which of the following would be most useful for preventing a particular genetic disorder?
- A.
A test that can determine whether a fetus suffers from the disorder
- B.
Knowing which chromosome bears the allele that causes the disorder
- C.
Tracing the trait back through parents and grandparents
- D.
Being able to identify carriers
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