Topic 11 : Chapter 14 : Mendel and the Gene Idea

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?

0

Black fur in mice (B) is dominant to brown fur (b). Short tails (S) are dominant to long tails (s). What fraction of the progeny of crosses BbSs × BBss will be expected to have black fur and long tails?

1/2

Having polydactyly (extra digits on hands and feet) is a dominant trait. A man has polydactyly. His wife and oldest daughter do not have polydactyly. The couple's second child has polydactyly. What is the probability that their next (third) child will have extra digits?

1/2

Albinism is a recessive trait where an individual does not produce the pigment melanin. A man and woman both produce melanin, but both have one parent with albinism. What is the probability that their first child will have albinism?

1/4

What fraction of the offspring from a cross between two animals with the genotype AaBbCc are expected to be homozygous recessive for the three traits?

1/64

1 pts Assuming independent assortment at all loci, what is the probability that a cross between the following parents, AABbCc × AaBbCc, will produce an AaBbCc offspring?

1/8

In a certain species of diploid fish a single gene controls skin color. Researchers have found four different alleles of this gene within the fish population. How many different gamete genotypes are possible in an individual of this species?

2

In rabbits, the homozygous genotype LCLC has straight 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 percent of the offspring would be expected to have deformed legs and white fur?

25%

A newly discovered diploid mammal has three characteristics that show simple Mendelian inheritance. Each characteristic is controlled by a single gene (A, B, or C). If a male with genotype AABBCc is crossed with a female with genotype AabbCc, what proportion of the offspring are expected to have the same phenotype as the male parent?

3/4

Phenylketonuria is an inherited disease caused by a recessive allele. If a woman and her husband are both carriers, what is the probability that their first child will be a girl without phenylketonuria?

3/8

When Mendel set up a Parental (P) cross between true breeding purple and white flowered plants to generate the F1 and then allowed the F1 to self-pollinate to generate the F2 he saw a dominant to recessive ratio of 3:1. What phenotypic ratio would be expected if he crossed the F1 with the original purple parent?

4:0

The following question refers to the figure of a family's pedigree chart, some of whose members exhibit the dominant trait, W. Affected individuals are indicated by a dark square or circle. What is the likelihood that a future child of IV-3 and IV-4 will have the trait?

50%

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

8

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. 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?

9 sharp-spined:3 dull-spined:4 spineless

Pea plants produce either purple or white flowers with purple showing complete dominance. A gardener was given plants with purple flowers. Which of the following types of crosses would best allow her to determine the genotype of her plant in one generation?

A testcross

Which of the following statements correctly explains the fact that all seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment?

All of the genes controlling the traits were on different chromosomes.

In human blood types, Rh positive is a trait that shows simple dominance over Rh negative. The Rh phenotype is recorded by stating "positive" or "negative" after the individuals ABO blood type. A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative. Which of the following phenotypes is possible for the father?

B positive

Albinism is a recessive trait where an individual does not produce the pigment melanin. A man and woman who both produce melanin have one child out of three who has albinism. What are the genotypes of the man and woman?

Both parents must be heterozygous.

Which of the following calculations require the use of the addition rule of probability?

Calculate the probability of a child having either sickle-cell anemia or cystic fibrosis if parents for each heterozygous for both.

Which of the following describes why Mendel continued some of his experiments into the F2 or F3 generation?

Following multiple generations allowed him to determine whether a recessive trait would reappear.

In a particular plant, green seed color is dominant to blue. If two plants with green seeds were crossed and resulted in 302 green and 98 blue seed plants, what was the most probable genotype of each parent?

Gg × Gg

A diploid animal is dihybrid at the Head shape (H) and Tail length (T) loci. Which of the following gamete genotypes can it produce?

Ht

Which of the following statements about the law of independent assortment is correct?

It describes the inheritance of different genes relative to one another.

Which of the following statements best describes the addition rule of probability?

It is the probability that either one of two independent events will occur.

Which of the following statements correctly explains the observation that parents with two different phenotypes produced offspring with a phenotype that is a blend of the two parental varieties?

Neither of the parental alleles is dominant over the other.

Why did all of the F1 offspring of Mendel's purple and white flowered pea cross always look like one of the two parental varieties?

One allele was dominant.

One of two major forms of neurofibromatosis results from inheriting a dominant allele of a gene with affected individuals having phenotypes that range from mild to very severe. Which of the following is the best explanation for why a young child is the first in her family to be diagnosed with a severe form of the condition?

One of the parents has a mild expression of the gene.

Which of the following relationships among alleles of a single gene best explains the observation that a single change in the gene encoding α-keratin results in chickens with frizzled feathers, increased food consumption, higher heart rate and delayed sexual maturity?

Pleiotropy

Phenylketonuria (PKU) is a recessive human disorder in which an individual cannot appropriately break down 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?

Regulate the individual's diet to severely limit the uptake of phenylalanine.

Mendel crossed true breeding yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F2 generation. The results were as follows: 6,022 yellow and 2,001 green (8,023 total). Which of the following statements correctly describes the relationship of the allele for green seeds to the allele for yellow seeds?

The green allele is recessive to the yellow allele.

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. A second gene, N, determines whether or not cactuses have spines. Homozygous recessive nn cactuses have no spines at all. Which of the following explain why a crossing a true breeding spineless cactus with a dull-spined cactus could result in both sharp- and dull-spined offspring?

The spineless cactus was heterozygous at the S locus

Which of the following sentences state a significant conclusion that Gregor Mendel drew from his experiments with pea plants?

Traits are inherited in discrete units and are not the result of "blending."

Which of the following statements correctly describes how Mendel explained why traits disappeared in the F1 generation and then reappeared in the F2 generation?

Traits can be dominant or recessive, and the recessive traits were "hidden" by the dominant ones in the F1.

Use the figure and the following description to answer the question.In a particular plant, leaf color 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-leaved plant is crossed with a light-leaved one, and the F1 offspring is allowed to self-pollinate. The predicted outcome of the F1 cross 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 homozygous?

Which of the boxes marked 1-4 correspond to plants that will be homozygous?

An obstetrician knows that her patient's fetus is at risk for a serious disorder that is detectable biochemically in fetal cells. The obstetrician would most reasonably offer which of the following procedures to her patient?

amniocentesis or CVS

Feather color 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?

blue and white offspring

A gene for the MN blood group has codominant alleles M and N. If both children in a family are of blood type M, which of the following situations is possible?

each parent is either M or MN

Ten plants of the same genotype are planted in a large flower garden. Later that year, some of the ten plants have blue flowers and others have pink flowers. This can be best explained by which of the following statements?

environmental factors such as soil pH affect the phenotype

Which of the following inheritance patterns describes the ability of a single allele to have multiple phenotypic effects?

pleiotropy

A radish is a root vegetable that produces flowers that may be red, purple, or white. A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring. The part of the radish we eat may be oval or long, with long being the dominant trait. If true-breeding red-flowered, long radishes long radishes are crossed with true-breeding white oval radishes, the F1 will be expected to exhibit which of the following phenotypes?

purple and long

Which of the following best describes how an individual with genotype AaBbCCDdEE can make haploid gametes with different genotypes?

the inheritance of a particular copy of one chromosome does not affect the inheritance of a different chromosome

In cattle, roan coat color (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?

white × roan

A brown dog crossed with a yellow dog produced 12 brown offspring. A second brown individual was obtained. When the yellow dog was crossed with this animal, six brown and six yellow offspring were born. Which of the following best explains the results of the second cross?

yellow is a recessive trait; brown is a dominant trait