Question 1

W. Affected individuals are indicated by a dark square or circle. 
- What is the likelihood that the offspring of IV-3 and IV-4 will have the trait?

Accepted Answer

A)  0% 
B)  50% 
C)  75% 
D)  100%

Question 2

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately metabolise the amino acid phenylalanine. This amino acid is not naturally produced by humans. Which of the following treatments would be most effective for people with PKU?

Accepted Answer

A)  Feed them the substrate that can be metabolised into phenylalanine. 
B)  Regulate the diet of the affected persons to severely limit the uptake of phenylalanine. 
C)  Feed the patients the missing enzymes in a regular cycle, such as twice per week. 
D)  Feed the patients an excess of the missing product.

Question 3

An obstetrician knows that one of her patients is a pregnant woman whose foetus is at risk for a serious disorder that is detectable biochemically in foetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient?

Accepted Answer

A)  karyotyping of the woman's somatic cells 
B)  X-ray 
C)  amniocentesis or CVS 
D)  blood transfusion

Question 4

Dark-shaded symbols represent individuals with one of the two major types of colon cancer. Numbers under the symbols are the individual's age at the time of diagnosis. Males are represented by squares, females by circles.  From this pedigree, this trait seems to be inherited ________.

Accepted Answer

A)  from mothers 
B)  as an autosomal recessive 
C)  as a result of epistasis 
D)  as an autosomal dominant

Question 5

In some parts of Africa, the frequency of heterozygosity for the sickle-cell anaemia allele is unusually high, presumably because this reduces the frequency of malaria. Such a relationship is related to which of the following?

Accepted Answer

A)  Mendel's law of independent assortment. 
B)  Mendel's law of segregation. 
C)  Darwin's explanation of natural selection. 
D)  The malarial parasite changing the allele.

Question 6

In a particular plant, leaf colour is controlled by gene locus D. Plants with at least one allele D have dark green leaves, and plants with the homozygous recessive dd genotype have light green leaves. A true-breeding, dark-leafed plant is crossed with a light-leafed one, and the FS1U1B11 S1U1B0offspring is allowed to self-pollinate. The predicted outcome of the FS1U1B12S1U1B0 is diagrammed in the Punnett square shown in the figure, where 1, 2, 3 and 4 represent the genotypes corresponding to each box within the square. 
-
Which of the boxes marked 1-4 correspond to plants that will be true-breeding?

Accepted Answer

A)  1 and 4 only 
B)  2 and 3 only 
C)  1, 2, 3 and 4 
D)  1 only

Question 7

In rabbits, the homozygous genotype LCLC has normal legs, LCLc results in deformed legs, and LcLc results in very short legs. The genotype FBFB produces black fur, FBFb brown fur, and FbFb white fur. If a cross is made between brown rabbits with deformed legs and white rabbits with deformed legs, what percentage of the offspring would be expected to have deformed legs and white fur?

Accepted Answer

A)  25% 
B)  33% 
C)  100% 
D)  50%

Question 8

Suppose two individuals with the genotype AaBbCc are mated. Assuming that the genes are not linked, what fraction of the offspring are expected to be homozygous recessive for the three traits?

Accepted Answer

A)  1/4 
B)  1/8 
C)  1/16 
D)  1/64

Question 9

Marfan syndrome in humans is caused by an abnormality of the connective tissue protein fibrillin. Patients are usually very tall and thin, with long spindly fingers, curvature of the spine, sometimes weakened arterial walls, and sometimes eye problems, such as lens dislocation. Which of the following would you conclude about Marfan syndrome from this information?

Accepted Answer

A)  It is recessive. 
B)  It is dominant. 
C)  It is pleiotropic. 
D)  It is epistatic.

Question 10

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

Accepted Answer

A)  The knowledge that multiple alleles are involved. 
B)  The allele for blue hydrangea is completely dominant over the allele for pink hydrangea. 
C)  The alleles are codominant. 
D)  Environmental factors such as soil pH affect the phenotype.

Question 11

Albinism (without melanin pigmentation) is a recessive trait. A man and woman both show normal pigmentation, but both have one parent who has albinism. What is the probability that their first child will have albinism?

Accepted Answer

A)  0 
B)  1/2 
C)  1/4 
D)  1

Question 12

W. Affected individuals are indicated by a dark square or circle. 
- What is the genotype of individual II-5?

Accepted Answer

A)  WW 
B)  Ww 
C)  ww 
D)  ww or Ww

Question 13

Assuming independent assortment for all gene pairs, what is the probability that a cross between the following parents, AABbCc × AaBbCc, will produce an AaBbCc offspring?

Accepted Answer

A)  1/2 
B)  1/16 
C)  1/8 
D)  3/4

Question 14

In cattle, roan coat colour (mixed red and white hairs) occurs in the heterozygous (CRCW) offspring of red (CRCR) and white (CWCW) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

Accepted Answer

A)  red × white 
B)  roan × roan 
C)  white × roan 
D)  red × roan

Question 15

In pea plants, the tall phenotype is dominant to the dwarf phenotype. If a heterozygous pea plant is crossed with a homozygous tall pea plant, what is the probability that the offspring will be dwarf in size?

Accepted Answer

A)  1 
B)  1/2 
C)  1/4 
D)  0

Question 16

Feather colour in budgies is determined by two different genes: Y for pigment on the outside of the feather, and B for pigment on the inside of the feather. YYBB, YyBB, or YYBb is green; yyBB or yyBb is blue; YYbb or Yybb is yellow; and yybb is white. A blue budgie is crossed with a white budgie. Which of the following results in the offspring is most possible?

Accepted Answer

A)  green offspring only 
B)  white offspring only 
C)  blue offspring only 
D)  blue and white offspring

Question 17

Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cacti have dull spines. At the same time, a second gene, N, determines whether or not cacti have spines. Homozygous recessive nn cacti have no spines at all. If cacti heterozygous for both traits, SsNn, were allowed to self-pollinate, the offspring would segregate into which of the following phenotype ratios?

Accepted Answer

A)  3 sharp-spined:1 spineless 
B)  1 sharp-spined:2 dull-spined:1 spineless 
C)  1 sharp-spined:1 dull-spined:1 spineless 
D)  9 sharp-spined:3 dull-spined:4 spineless

Question 18

Mendel continued some of his experiments into the F2 or F3 generation in order to ________.

Accepted Answer

A)  obtain a larger number of offspring on which to base statistics 
B)  observe whether or not a recessive trait would reappear 
C)  observe whether or not the dominant trait would reappear 
D)  distinguish which alleles were segregating

Question 19

Phenylketonuria is an inherited disease caused by a recessive autosomal allele. If a woman and her husband are both carriers, what is the probability that their first child will be a phenotypically normal girl?

Accepted Answer

A)  1/4 
B)  1/16 
C)  3/16 
D)  3/8

Question 20

Radish flowers may be red, purple or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The flower colour trait in radishes is an example of which of the following inheritance patterns?

Accepted Answer

A)  a multiple allelic system 
B)  sex linkage 
C)  codominance 
D)  incomplete dominance

Exam 14: Mendel and the Gene Idea

W. Affected individuals are indicated by a dark square or circle. - What is the likelihood that the offspring of IV-3 and IV-4 will have the trait?