Review Sheet Ch. 11
Be sure you have read all of Chapter 11 and review all notes and handouts
1. How is a karyotype created?
Ans. A genetic test called amniocentesis is performed on the mother.
2. During what reproduction process does non-disjunction occur?
Ans. Meiosis (because sex chromosomes do not separate properly). Non disjunction does not
occur during mitosis!
3. Can a person phenotype change? If yes give an example
Ans. Yes dyeing your hair another color
4. What blood types are possible in the children when a heterozygous B man marries a
heterozygous A woman?
Ans. Ai X Bi produces AB, Ai, Bi, and ii
5. What is epistasis?
Ans. Epistasis occurs when one allele hides the effect of another allele
6. What is a sex-linked trait?
Ans. It is trait on the X chromosome. Nothing on the Y chromosome!
7. Why do sex-linked traits show up more often in boys?
ANs. Boys only have one X chromosome (they are XY) so sexlinked traits can show up in boys
even if they were recessive.
8. If a female fruit fly heterozygous for red eyes (XRXr) crossed with a white-eyed male Xr Y), what
percent of their offspring would have white eyes?
ANs. The cross will produce XRXr, XRY, XrXr , XrY. Two out of four offsprings have white
eyes: XrXr , XrY so it will be 50%
9. What type of inheritance pattern occurs in Roan cattle?
Ans. Codominance
10. How many alleles are needed to pass on a dominant trait like Huntington’s disease?
Ans. Only one because a phenotype that results from a dominant allele must have at least one
dominant allele present in the parent.
11. List two human traits that are polygenic.
Ans. Two polygenic traits would be skin color and height and will show a distribution such as
in the bell shaped curve in the graph below where there would be more intermediate
phenotypes (average) than the extremes:
12. A man heterozygous for blood type A marries a woman heterozygous for blood type B. What is
the chance they will have an O baby?
Ans. The cross between a Ai X Bi will produce the following offsprings:
2AB, Ai, Bi so they have 0% chance of a type O baby.
13. According to Figure 11-4, what is the chance that individual A will be afflicted with the disease?
14. List the possible genotypes for A blood type and B blood type.
Ans. Genotypes for A blood type are : AA and Ai
Genotypes for B blood type are: BB and Bi
15. How does nondisjunction cause disorders?
Ans. It alters the chromosome number
16. What part of the chromosome might be involved in aging and cancer?
(deleted from the test)
17 What breed of dogs’ shows epistasis?
Ans. Labrador retrievers is controlled by two set of alleles. So there can be
black:chocolate:yellow and this is an example of epistasis
17. What is an amniocentesis?
Ans. Genetic test done to help create the karyotype of a fetus
18. How many pairs of chromosomes are in a normal human karyotype?
Ans. Humans have 23 pairs of chromosomes, the first 22 pairs are known as autosomes the
last pair are called the sex chromosomes.
19. How can you detect Down syndrome from a karyotype?
Ans. they have an extra chromosome – pair 21 has three chromosomes instead of two as
seen in the karyotype below:
20. What is an autosome? How many do humans have?
Ans. Humans have 22 pairs of autosomes. These are the non sex (regular) chromosomes.
21. The sex chromosomes in females are ____ and in males____.
Ans. XX in females and XY in males. The father is responsible for giving the y chromosome
to the son.
22. What is incomplete dominance and how is it shown in a cross?
Ans. Example Red-RR White-WW and Pink is RW(incomplete dominance)
23. What is codominance?
Ans. Example red and white cows are mated to give roan cows. Roan cows consist of both
red and white hairs because the red and the traits white are both codominant
24. What color or pattern is an indicator of codominance?
Ans. In some animals, stripping or spotting appears due to codominance.
25. Which disorders from your foldable are recessive?
Ans. albino, Tay sachs, galactosemia, and cystic fibrosis
26. How is sickle-cell anemia treated?
Ans. Deleted from the test
27. Which disorder cause excessive mucus?
Ans. Cystic fibrosis
.
28. What can you tell from the pedigree about individual III-2?
Ans. Male with a disorder
29. What do the shaded symbols mean?
Ans. Disorder