Chapter 7

Question 1

Most genes come in alternative forms called

Answer 1

alleles

Question 2

Albinism is caused by a recessive autosomal allele. A woman and man, both normally pigmented, have an albino child together. For this trait, what is the genotype of the albino child?

Answer 2

homozygous recessive

Question 3

Which of the following pairings of blood type phenotypes CANNOT produce a child with type B blood?

Answer 3

AO x AO

Question 4

The phenotype of an organism is:

Answer 4

its physical characteristics/consists of the observable properties of an individual

Question 5

A diploid individual with two identical alleles for a particular gene is said to be:

Answer 5

homozygous for that gene

Question 6

The same genetic condition that causes sickle-cell anemia can also protect against:

Answer 6

malaria

Question 7

In certain plants, red flowers are dominant to white flowers. If a heterozygous plant is crossed with a homozygous red-flowered plant, what is the probability that the offspring will be white-flowered?

Answer 7

0%

Question 8

In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for purple flowers are crossed, in the offspring:

Answer 8

all of the flowers will be purple

Question 9

In snapdragons, there is an allele for flower color, CW, that produces no pigment. A plant with the genotype CWCW will produce _____________ flowers.

Answer 9

white

Question 10

An allele: a) can be dominant or recessive, b) will assort independently from alleles on other chromosomes, c) can be identical to or different from its sister allele for any gene in a somatic cell, or d) can be one of several alternative forms of a gene

Answer 10

all of the above

Question 11

A person with the genotype AB can receive blood of what type?

Answer 11

all types; it’s the universal recipient.

Question 12

How can an individual carry a defective gene but not exhibit the defective phenotype?

Answer 12

individuals carry two copies of gene instructions, and one dominant allele could mask the presence of a recessive defective allele

Question 13

Which of the following did Gregor Mendel never see?

a) a stamen
b) the expression of an allele
c) a hybrid
d) an F2 generation
e) a chromosome

Answer 13

a chromosome

Question 14

Which about dominant traits is correct?

Answer 14

the dominant trait is the one which is expressed

Question 15

The law of segregation states that:

Answer 15

each of two alleles for a given trait segregate into different gametes

Question 16

Some genes, such as the human ABO blood groups, have more than two alleles. For these genes:

Answer 16

individuals can only possess two alleles

Question 17

Vampire bats:

Answer 17

will sometimes regurgitate blood into the mouth of an unrelated individual that is close to starving

Question 18

Evolution occurs:

Answer 18

only via natural selection, genetic drift, migration, or mutation

Question 19

Sickle-cell anemia is a genetic disease caused by the presence of a faulty hemoglobin gene (HbS). The normal version of this gene is HbA. Which of the following is TRUE about HbS and HbA?

Answer 19

they’re both alleles for the same trait

Question 20

Cystic fibrosis, which is usually lethal before reproductive ages, is a homozygous recessive disease. Why do cases continue to arise, even though people with the disease rarely live to reproduce?

Answer 20

The harmful allele can reside in heterozygous individuals with few to no negative effects.

Question 21

In pea plants, purple flower color is dominant to white flower color. If two pea plants that are true-breeding for purple flowers are crossed, in the offspring:

Answer 21

all of the flowers will be purple

Question 22

A plant with pink flowers is allowed to self-pollinate. Generation after generation, it produces pink flowers. This is an example of:

Answer 22

a true-breeding plant

Question 23

The failure of a seedling to turn green if grown in the dark is an example of:

Answer 23

interaction between genotype and environment

Question 24

Which of the following statements about a rare, X-linked dominant condition in humans is INCORRECT?

Answer 24

The son of a woman with this condition has a 100% chance of also having this condition

Question 25

In many species of birds males are XX and females are XZ. With birds like this who is most likely to display a sex-linked recessive trait?

Answer 25

females

Question 26

If you have blood type A, which of the following is true about you?

Answer 26

you have A antigens

Question 27

In snapdragons, there is an allele for flower color, CW, that produces no pigment. A plant with the genotype CWCW will produce _____________ flowers.

Answer 27

white

Question 28

Which of the following results would mean that a test-cross investigation was complete, given that a pigmented alligator (M_) is crossed with an albino alligator (mm)?

Answer 28

getting a single albino offsrping

Question 29

The impact of a single gene on more than one characteristic is called:

Answer 29

pleitropy

Question 30

In pea plants, tall stem length is dominant to short and round seed shape is dominant to wrinkled seed shape. If a plant that is homozygous for tall stem and homozygous for wrinkled seeds is allowed to self-fertilize, what proportion of the offspring will have wrinkled seeds and a tall stem?

Answer 30

All of the offspring will have wrinkled seeds & a tall stem

Question 31

The ABO blood type system in humans is an example of:

Answer 31

multiple alleles and codominance

Question 32

The SRY gene is considered pleiotropic because:

Answer 32

it is a single gene that influences multiple traits: development of fetal gonads, secretion of testosterone, and more

Question 33

Jay has type O blood, and his brother Alon has type AB blood. What are the genotypes of these boys’ parents?

Answer 33

I^Ai and I^Bi

Question 34

Phenylketonuria (PKU) is a disease characterized by the buildup of phenylalanine. The enzyme phenylalanine hydroxylase, which catalyzes the conversion of _________ to __________, is mutated and non-functional.

Answer 34

phenylalanine; tyrosine

Question 35

the term diploid refers to cells that have:

Answer 35

two copies of each chromosome (in humans that is two sets of 23 chromosomes, for 46 chromosomes in total)

Question 36

the term haploid refers to cells that have:

Answer 36

one copy of each chromosome.

Question 37

somatic cells are _______, and gametes, the cells produced in meiosis, are _______

Answer 37

diploid, haploid