Deck 11: Mendel and His Discoveries

Question 1

What is considered a "black box in biology?

A) various cellular organelles
B) any of a number of expensive automated scientific machines
C) processes in which we know only input and output
D) patented devices whose mechanisms are known only by the manufacturer
E) an old camera

Answer 1

processes in which we know only input and output

Question 2

Which type of allele, or allelic combination, can be present in an individual without affecting phenotype?

A) dominant
B) heterozygous dominant
C) homozygous recessive
D) recessive
E) homozygous dominant

Answer 2

recessive

Question 3

Which of the following did Gregor Mendel not illustrate?

A) Identical phenotypes do not necessarily mean organisms have identical genotypes.
B) Units of inheritance come in pairs.
C) Phenotypic characteristics do not "blend" over many generations.
D) Inheritance is caused by discrete particles.
E) Units of inheritance are found on chromosomes.

Answer 3

Units of inheritance are found on chromosomes.

Question 4

Refer to the figure above and then answer the question that follows.

-In his basic experiments, Mendel began with true-breeding parental (P) plants. What did he see when he cross-fertilized P plants that had different traits?

A) The F₁ plants had new traits that were a blend of P traits.
B) All F₁ plants had the trait of one or the other P plant.
C) The F₁ plants had an entirely new trait, not seen in either P plant.
D) The F₁ plants showed a combination of the two P traits in a 1:1 ratio.
E) The F₁ plants showed a combination of the two P traits, in a 3:1 ratio.

Question 5

Refer to the figure above and then answer the question that follows.

-Before Mendel, people had observed inheritance of dominant and recessive traits by following many generations of plants and animals. What was different about Mendel's work?

A) He used a plant that had never been cultivated before.
B) He kept careful count of his results, including mathematical analysis.
C) His results were immediately accepted and applied to other studies.
D) He followed more generations than anyone else.
E) He did both cross- and self-fertilizations.

Question 6

Crossing red flowering snapdragons with white flowering snapdragons yields seeds that grow into snapdragons with pink flowers. This suggests that:

A) red flowers are dominant.
B) white flowers are dominant.
C) pink flower are dominant.
D) incomplete dominance is occurring.

Question 7

Cystic fibrosis (CF) is caused by a recessive allele. A child has CF, even though neither of his parents has CF. What can you conclude about the parents?

A) One is homozygous dominant for the CF gene, and the other is heterozygous.
B) One is homozygous recessive for the CF gene, and the other is heterozygous.
C) They are both homozygous recessive for the CF gene.
D) They are both homozygous dominant for the CF gene.
E) They are both heterozygous for the CF gene.

Question 8

In humans, "unattached earlobes are dominant over "attached earlobes. A woman and a man, both with unattached earlobes, have a child with attached earlobes. What is the probability their next child will have attached earlobes?

A) 3/4
B) 1/4
C) 2/4
D) 4/4
E) 0

Question 9

If an individual exhibits a recessive trait, which of the following statements can you be sure of?

A) The phenotype for this trait is different from the phenotype of the homozygous dominant genotype for this trait.
B) The genotype of this trait will be heterozygous.
C) Both parents of this individual had the same genotype for this trait.
D) Any siblings of this individual will have the same phenotype for this trait.
E) Any children this individual has will always exhibit the trait, regardless of the genotype of the other parent.

Question 10

Analyze the validity of the two statements below: Statement A: If an individual is heterozygous for a particular trait, it means that the individual carries two different alleles on a set of homologous chromosomes. Statement B: If an individual is heterozygous for a particular trait, that individual produces dominant gametes 50 percent of the time.

A) Statement A is true; Statement B is false.
B) Both statements are true.
C) Statement A is false; Statement B is true.
D) Both statements are false.

Question 11

Alleles that are dominant are:

A) more common than recessive alleles.
B) generally more evolutionarily advantageous than recessive alleles.
C) capable of hiding or masking a recessive allele.

Question 12

In the individual with genotype AaBB, what percentage of gametes will contain the A allele?

A) 75 percent
B) 25 percent
C) 100 percent
D) 10 percent
E) 50 percent

Question 13

How many different types of gametes can be generated by an individual with genotype AaBB?

A) two
B) three
C) eight
D) one
E) four

Question 14

The phenotypic ratio obtained in a dihybrid cross is 8:0:4:2. The number of offspring that are dominant for trait 1 and recessive for trait 2 is:

A) zero
B) two
C) four
D) eight

Question 15

A "trihybrid cross would:

A) follow a gene for which there are three alleles.
B) be a cross involving gametes from three different individuals.
C) follow three traits in a cross.
D) follow a gene that affects three different traits.
E) follow a trait over three generations.

Question 16

In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles, and P and p for the flower color alleles. Flower color and seed color assort independently. If a YyPp plant is crossed to a Yypp plant, what is the probability that the resulting plant will have the genotype Yypp? (Hint: Determine two separate probabilities, and use the rule of multiplication.)

A) 1/2
B) 1/8
C) 1/32
D) 1/16
E) 1/4

Question 17

In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles, and P and p for the flower color alleles. Flower color and seed color assort independently. A plant of unknown genotype with yellow seeds and purple flowers is crossed to a plant with green seeds and white flowers. The offspring all have yellow seeds, but some have purple flowers and some have white flowers. What is the genotype of the yellow-seeded, purple-flowered plant?

A) YyPp
B) YYPp
C) YyPP
D) YYPP
E) Yypp

Question 18

In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles, and P and p for the flower color alleles. Flower color and seed color assort independently. A true-breeding plant with green seeds and white flowers is crossed to a plant that is heterozygous for the genes for both phenotypes. What is the probability that the cross will yield a plant with green seeds and white flowers?

A) 3/16
B) 3/32
C) 1/32
D) 1/16
E) 1/4

Question 19

In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles, and P and p for the flower color alleles. Flower color and seed color assort independently. If a plant that is heterozygous for both flower color and seed color genes is self-fertilized, what proportion of the offspring will have one of the dominant phenotypes, either the seed color or flower color, but not both?

A) 6/64
B) 6/32
C) 6/16
D) 9/32
E) 9/16

Question 20

In Mendel's pea plants, yellow seeds are dominant to green seeds. Purple flowers are dominant to white flowers. Use Y and y for the seed color alleles, and P and p for the flower color alleles. Flower color and seed color assort independently. What is the relationship between the Y and P?

A) They are two different genes on two different chromosomes.
B) They are two different genes on the same chromosome.
C) They are two different chromosomes in the pea plant.
D) They are the pleiotropic effects of a single gene.
E) They are incompletely dominant alleles of the same gene.

Question 21

If all of Mendel's monohybrid crosses had involved traits that function by incomplete dominance, would his results have supported blending inheritance?

A) It cannot be determined with the information given.
B) Yes; a cross between red and white flowers would yield all pink offspring.
C) No; half of the offspring would be red or white.
D) Yes; there is always a wide range of phenotypes in monohybrid crosses.

Question 22

A, B, and O blood type in humans is controlled by a single gene with three alleles: I^A, I^B and i. Imagine a fourth allele for blood type, I^C. If it is codominant with I^A and I^B, and dominant to i, how many possible blood type phenotypes are there?

A) six
B) three
C) eight
D) nine
E) seven

Question 23

A, B, and O blood type in humans is controlled by a single gene with three alleles: I^A, I^B and i. Type O is the recessive trait. The i allele is recessive to both I^A and I^B. Which of the following could be possible genotypes of the parents of a person with type O blood?

A) I^A I^B and ii
B) both parents must be ii
C) I^Ai and I^A I^A
D) I^Ai and I^Bi
E) I^A I^B and I^A I^B

Question 24

Sickle-cell anemia is a disease whose phenotype includes not only anemia, but also damage to many different organs. All phenotypes, however, can be traced to a single gene. This is an example of :

A) multiple alleles.
B) pleiotropy.
C) codominance.
D) dominance.
E) incomplete dominance.

Question 25

The one gene, one phenotype model:

A) is well supported by available evidence.
B) is usually the relationship in inheritance.
C) is not a good model because aspects of phenotypes are often controlled by many genes.

Question 26

What are the odds of tossing a coin and having it come up heads three times in a row?

A) 1/3 1/3 1/3
B) 25 percent
C) 50 percent
D) 1/2 1/2 1/2
E) 1/2 1/3 1/4

Question 27

To determine the probability of two events occurring at the same time,

A) one probability is divided by the other.
B) the two probabilities are multiplied.
C) the individual probabilities are added, then subtracted from 1.
D) the two probabilities are added.
E) one probability is subtracted from the other.

Question 28

If one in 10 people carries the I^A allele, and one in 20 people carries the I^B allele, what is the probability that one person will have the I^A I^B genotype?

A) 1/30
B) 1/2
C) 1/200
D) 1/10
E) 2/30

Question 29

Match Mendel's results in column 1 with the conclusion he drew from them in column 2.

-When true-breeding P plants of different types are crossed, the offspring do not have a phenotype intermediate between the two parents.

A) There is no "blending" in inheritance.
B) Alleles come in dominant and recessive forms.
C) Genes assort independently in gamete formation.
D) Organisms have two alleles of each gene (elements), and only one is passed to offspring.

Question 30

Match Mendel's results in column 1 with the conclusion he drew from them in column 2.

-When true-breeding P plants are crossed, all offspring had the trait of one of the parents.

A) There is no "blending" in inheritance.
B) Alleles come in dominant and recessive forms.
C) Genes assort independently in gamete formation.
D) Organisms have two alleles of each gene (elements), and only one is passed to offspring.

Question 31

Match Mendel's results in column 1 with the conclusion he drew from them in column 2.

-When F₂ plants, all with the heterozygous phenotype, are self-fertilized, the offspring have dominant and recessive traits in a 3:1 ratio.

A) There is no "blending" in inheritance.
B) Alleles come in dominant and recessive forms.
C) Genes assort independently in gamete formation.
D) Organisms have two alleles of each gene (elements), and only one is passed to offspring.

Question 32

Match Mendel's results in column 1 with the conclusion he drew from them in column 2.

-When two traits are followed in a dihybrid cross, heterozygotes give offspring with all combinations of phenotypes, in a 9:3:3:1 ratio.

A) There is no "blending" in inheritance.
B) Alleles come in dominant and recessive forms.
C) Genes assort independently in gamete formation.
D) Organisms have two alleles of each gene (elements), and only one is passed to offspring.

Question 33

Why do you think Mendel cross-fertilized plants in the P generation, but self-fertilized in the F₁ generation?

Question 34

What might be the current status of genetics if Mendel had never done his experiments with garden peas?

Question 35

Researchers involved in the Human Genome Project are working to determine the genetic causes of many diseases. In some cases, an allele has been identified that is associated with the particular disease, and a test for that allele can be performed. If a person tests positive for that allele, it does not always mean that they will develop the disease. Explain what else might be a factor in whether the person actually develops the disease.

Question 36

Consider the following information for a dihybrid cross. The dominant allele F codes for freckles, whereas the recessive allele f codes for no freckles. The dominant allele E codes for long eyelashes, whereas the recessive allele e codes for short eyelashes. Both parents have the genotypes of ee and Ff. Indicate the following: (1) the phenotype of both parents, (2) the possible gametes that each parent can make, (3) all of the possible phenotypes for the offspring, and (4) the phenotypic ratio obtained after the Punnett square is drawn.