Deck 2: Heredity and Evolution

Question 1

What is the term for the condition of two copies of the same allele being present in the genotype?

A) dominant
B) codominant
C) recessive
D) homozygous
E) segregated

Answer 1

D

Question 2

In Mendel's experiments, what was the ratio of tall to short plants in the F2 generation?

A) 15 to 1
B) 3 to 1
C) ½ tall, ½ short
D) 4 to 1
E) 5 to 1

Answer 2

B

Question 3

In Mendel's experiments, the tall parental (P) plants

A) were homozygous for the allele for tallness
B) were heterozygous at the locus controlling height
C) could NOT be crossed with short plants
D) were homozygous for the allele for shortness
E) were heterozygous for the allele for shortness

Answer 3

A

Question 4

Which statement concerning the F1 plants in Mendel's experiments is false?

A) They were hybrids.
B) They were heterozygous for the traits in question.
C) Their parents were homozygous for the traits in question.
D) All F1s displayed the dominant trait in their phenotype.
E) All F1s displayed the recessive trait in their phenotype.

Question 5

The ABO blood type system consists of ______ alleles.

A) 6
B) 4
C) 3
D) 2
E) 5

Question 6

How many ABO phenotypes (blood types) are there?

A) 4
B) 2
C) 3
D) 6
E) 1

Question 7

Gregor Mendel is known for which of the following?

A) He developed theories of evolutionary change.
B) He discovered the structure of the DNA molecule.
C) He studied characteristics that are influenced by several genetic loci.
D) He discovered the fundamental principles of how traits are inherited.
E) He developed the theory of inheritance of acquired characteristics.

Question 8

According to the principle of independent assortment there is a __________chance that any tall pea plant will produce either yellow or green peas.

A) 0 percent
B) 25 percent
C) 50 percent
D) 75 percent
E) 100 percent

Question 9

What is an individual's actual genetic make-up called?

A) phenotype
B) homozygosity
C) recessiveness
D) phenotypic ratio
E) genotype

Question 10

Mendelian traits

A) are governed by more than one genetic locus
B) occur only in some people
C) are always dominant
D) are governed by one genetic locus
E) are always recessive

Question 11

When Mendel crossed true breeding tall and short parental plants, what was produced?

A) All the offspring were tall.
B) Half the offspring were tall, the other half were short.
C) All the offspring were short.
D) The offspring were intermediate in height relative to the two parent plants.
E) About 90 percent were tall, but the rest were short.

Question 12

Which of the following is not a polygenic trait?

A) stature
B) skin color
C) eye color
D) ABO blood type
E) hair color

Question 13

Mendelian traits are described as discrete, or discontinuous because

A) Their phenotypic expressions overlap
B) Their phenotypic expressions do not fall into clearly defined categories
C) Their genotypic expression overlap
D) Their genotypic expressions do not fall into clearly defined categories
E) Their phenotypic expressions do not overlap

Question 14

Gregor Mendel

A) published his results and won the Nobel Prize for his discoveries
B) was trained as a geneticist
C) did not know about chromosomes
D) was a professor at the University of Vienna
E) never published his work

Question 15

In a hypothetical situation, B is the allele that causes brachydactyly. If a man who has normal fingers (bb) and a woman with brachydactyly (Bb) have children, what proportion of these children would you expect to have normal fingers? (Hint: Use a Punnett square).

A) None
B) All
C) 1/4
D) 3/4
E) 1/2

Question 16

How do the basic principles of inheritance, identified by Mendel in plants, differ from those in humans?

A) They are simpler.
B) Plants don't have alleles.
C) There are no differences since the basic principles are the same.
D) There are no Mendelian traits in humans.
E) The number of chromosomes is different; therefore the genetic principles are different.

Question 17

A person who is homozygous recessive at a locus has which of the following?

A) two copies of the recessive allele
B) two copies of the dominant allele
C) an autosomal trisomy
D) a recessive allele on the X chromosome only
E) a recessive allele on the Y chromosome only

Question 18

What is type AB blood an example of?

A) codominance
B) blending
C) recessiveness
D) dominance
E) polygenic inheritance

Question 19

What is it called when a person possesses two different alleles at the same locus, and both alleles are expressed in the phenotype?

A) recessiveness
B) codominance
C) dominance
D) homozygosity
E) X-linkage

Question 20

What is the term used to refer to the observable, physical expression of genotypes?

A) genotype
B) phenotype
C) phenotypic ratio
D) genotypic ratio
E) independent assortment

Question 21

Evolution can be most succinctly defined as

A) the appearance of new species
B) the change from one species to another in one generation
C) the change in allele frequency from one generation to the next
D) any type of genetic mutation
E) genetic drift

Question 22

All human genetic disorders are inherited as recessive traits.

Question 23

What produces new alleles at a locus?

A) natural selection
B) recombination
C) mutation
D) migration
E) genetic drift

Question 24

The HbS allele increased in frequency in West African populations due to which of the following?

A) sickle-cell anemia
B) genetic drift
C) migration
D) increased mutation rates
E) natural selection

Question 25

Which of the statements below is false regarding the relationship between malaria and the HbS allele?

A) There is no geographic correlation between the distribution of the HbS allele and malaria.
B) Heterozygotes have greater resistance to malaria than homozygous individuals.
C) The malarial parasite does not reproduce very well in the red blood cells of heterozygotes.
D) Malaria is caused by the Plasmodium parasite.
E) Most people are homozygous for the HbA allele.

Question 26

Two people (both heterozygotes) are able to taste a chemical substance called PTC. The ability to taste PTC is caused by a dominant allele (T). The inability to taste PTC is caused by a recessive allele (t). What proportion of their offspring would be expected to be heterozygous?

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

Question 27

Recessive conditions are usually associated with the lack of production of an enzyme.

Question 28

Genetic drift is

A) the change in allele frequencies produced by random factors
B) the result of large populations
C) the opposite of founder effect
D) not evolutionary change
E) the change in allele frequencies produced by nonrandom factors

Question 29

What does each mitochondrion contain?

A) nuclear DNA
B) 46 chromosomes
C) an X but never a Y chromosome
D) several copies of a ring-shaped DNA molecule, or chromosome
E) A Y but never an X chromosome

Question 30

Polygenic traits

A) are discrete
B) have a continuous range of expression
C) are controlled by only one genetic locus
D) include the ABO blood type system and cystic fibrosis
E) are also called Mendelian traits

Question 31

Evolution can be described as a two-stage process that includes which of the following?

A) genetic drift followed by migration
B) natural selection followed by migration
C) recombination followed by mutation
D) production of variation followed by natural selection acting on this variation
E) production and distribution of variation

Question 32

Two people (both heterozygotes) are able to taste a chemical substance called PTC. The ability to taste PTC is caused by a dominant allele (T). The inability to taste PTC is caused by a recessive allele (t). What proportion of their children would be expected not to be able to taste PTC?

A) 3/4
B) All
C) 1/4
D) 2/3
E) none

Question 33

Two people (both heterozygotes) are able to taste a chemical substance called PTC. The ability to taste PTC is caused by a dominant allele (T). The inability to taste PTC is caused by a recessive allele (t). What proportion of their children would be expected to have the ability to taste PTC?

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

Question 34

What is gene flow defined as?

A) production of new alleles
B) production of new genetic material
C) chance loss of alleles in a population
D) exchange of genes between populations
E) differential reproductive success of individuals

Question 35

At a hypothetical locus, a man's genotype is Aa. What proportion of his gametes would be expected to receive the A allele?

A) All
B) ½
C) ¾
D) ¼
E) None

Question 36

Which of the following types of traits are governed by more than one genetic locus?

A) polygenic
B) dominant
C) Mendelian
D) recessive
E) pleiotropic

Question 37

Which statement concerning polygenic traits is not true?

A) They are governed by more than one genetic locus.
B) Their expression is often influenced by genetic/environmental interactions.
C) The alleles have an additive effect on the phenotype.
D) They are continuous traits
E) The most frequently discussed are skin, hair and eye color.

Question 38

In order for a mutation to be passed on to offspring, the mutation must

A) occur in a gamete
B) be beneficial
C) occur in a somatic cell
D) result in additional chromosomes
E) have negative evolutionary consequences

Question 39

What is the only source of new genetic material in any population?

A) mutation
B) genetic drift
C) founder effect
D) migration
E) natural selection

Question 40

Which of the following is not inherited in a Mendelian fashion?

A) Huntington Disease
B) albinism
C) cleft chin
D) Tay-Sachs disease
E) skin color

Question 41

Mitochondrial DNA (mtDNA) is extremely useful for studying genetic change over time.

Question 42

Explain Mendel's principle of independent assortment.

Question 43

In regions where malaria is present, it acts as a selective agent that favors the heterozygous phenotype, because people with sickle-cell trait produce more offspring than those with only normal hemoglobin, who may die of malaria.

Question 44

New alleles are the results of mutations.

Question 45

Polygenic traits account for few, if any, of the readily observable phenotypic variation seen in humans.

Question 46

What are the typical Mendelian phenotypic and genotypic ratios in the F2 generation for a cross of purebred tall and short plants? Why are these ratios typical?

Question 47

Explain why a woman with type O blood and a man with type A blood could potentially have children with either type A or O blood.

Question 48

Define genetic drift. How are founder effect and genetic drift related?

Question 49

Melanin production is the result of interactions between several different loci.

Question 50

Why is mutation an important element in accounting for the variation in mtDNA? What are the factors that redistribute genetic variation?

Question 51

Explain the concepts of dominance, co-dominance, and recessiveness as used in modern genetics.

Question 52

What is the effect of genetic bottlenecks on human and nonhuman species?

Question 53

The genotype sets limits and potentials for development and interacts with the environment to produce the phenotype.

Question 54

Genetic drift is the random factor in evolution.

Question 55

A manifestation of sickle-cell anemia is the abnormal hemoglobin S reduces the ability of red blood cells to transport oxygen throughout the body.

Question 56

Dominance and recessiveness are all-or-nothing situations because the recessive allele has no phenotypic effects in heterozygotes.

Question 57

The relationship between malaria and the HbS allele is an example of natural selection as a factor that can cause directional change in allele frequencies.

Question 58

Explain how two parents who do NOT express a particular trait in their phenotype can nevertheless produce children who express the trait. Give an example of a specific trait or disease where this could occur.

Question 59

Explain Mendel's principle of segregation.

Question 60

What is meant by the statement, "natural selection is the one factor that can cause directional change in allele frequency relative to specific environmental factors"?

Question 61

Using the HbS allele to illustrate, describe why fitness levels are a function of the environment.

Question 62

Discuss the differences between Mendelian and polygenic modes of inheritance. Provide an example of a Mendelian and a polygenic trait.

Question 63

Allele frequencies are indicators of the genetic makeup of a population. Use the example of ABO blood types to show how allele frequencies change.