中国大学MOOC 遗传学（英文）-西北农林科技大学 测验与作业答案

Chapter 1 Introduction to Genetics

1 The contribution of Gilbert and Sanger to modern genetics was to: 
develop the PCR technique. 

discover DNA in the nucleus of cells.

describe the structure of DNA.

show that genes were made of DNA.
喵查答案：develop a method for sequencing DNA.

2 The contribution Charles Darwin made to genetics was to:
demonstrate the connection between Mendel’s principles of inheritance and evolution.
喵查答案：

propose that evolution occurs by natural selection.
develop the theory of evolution, based on earlier theories of population genetics.

connect the fields of evolution and molecular genetics.

3 Which of the following scientists contributed significantly to the foundations of transmission genetics?

James Watson
喵查答案：Thomas Hunt Morgan 
John B. S. Haldane
Charles Darwin

4 Which of the following would serve least well as a model for understanding basic mechanisms of inheritance?
fruit flies
喵查答案：

humans

yeast

mice
zebrafish

5 Which of the following species is considered a genetic model organism?

the plant, Linaria vulgaris
the deer mouse, Peromyscus maniculatus
喵查答案：the worm, Caenorhabditis elegans
the frog, Hyla chrysoscelis
the chimpanzee, Pan troglodytes

6 Genetic information can be carried in which of the following biomolecules?

Proteins
DNA and not RNA

RNA and not DNA
喵查答案：Either DNA or RNA

7 The first complete DNA sequence of a non-viral, free-living organism was obtained for:

a bacterium in 1900.
a bacterium in 1945.
喵查答案：

a bacterium in 1995.

humans in 1990.

humans in 2000.

8 Evolution cannot occur without genetic changes in populations. 
喵查答案：正确
错误

9 Some phenotypes or traits, such as hair color, are determined by the information provided by more than a single gene. 
喵查答案：正确
错误

10 Charles Darwin accurately described the laws of inheritance in his landmark book, On the Origin of Species.
喵查答案：正确
错误

11 Some viruses have RNA as their genetic information. 
喵查答案：正确
错误

12 Bacteria and viruses can be used to study genes and inheritance, even though they are structurally and metabolically different from animal and plant cells.
喵查答案：正确
错误

13 Many human traits, such as skin and hair color, exhibit blending inheritance, in which genetic information is mixed and is not separated in future generations.  
正确
喵查答案：错误

14  The theory of pangenesis states that all living organisms are composed of cells. 
正确
喵查答案：错误

15 Humans first applied genetics to the domestication of plants and animals between approximately 10,000 and 12,000 years ago. 
喵查答案：正确
错误

Chapter 2 Chromosomes and Cellular Reproduction

1 Which of the following statements is FALSE?
Generally, chromosomes of prokaryotes are circular.
Prokaryotes usually have a single molecule of DNA.
喵查答案：Generally, chromosomes of eukaryotes are circular.
Eukaryotes usually have multiple chromosomes.
Eukaryote chromosomes are usually linear.

2 Which of the following are NOT prokaryotes?
eubacteria
archaea
喵查答案：viruses
ancient bacteria

3 Which of the following statements is FALSE?
喵查答案：Errors in chromosome separation are rarely a problem for an organism.
Errors in chromosome separation can result in a miscarriage.
Errors in chromosome separation can result in cancer.
Errors in chromosome separation can result in a child with severe handicaps.
Errors in chromosome separation can cause numerous problems for an organism.

4 Suppose that a diploid cell contains 8 chromosomes (2n = 8).  How many different combinations in the gametes are possible?
2
4
8
喵查答案：16
64

5 What process is unique to plants?
meiosis
喵查答案：double fertilization
crossing over
haploid gametes

spermatogenesis

6 In order to be functional, a eukaryotic chromosome requires all of the following except:
a centromere.
origins of replication.
喵查答案：a nucleoid.
telomeres.

7 In eukaryotes, chromosomes do not contain:
喵查答案：ribosomes.
chromatin
proteins
histones
DNA

8 A dividing eukaryotic cell is treated with a drug that inhibits the molecular motors associated with kinetochores.  At which cell cycle stage would it stop?
G1
S
G2
喵查答案：M (anaphase)
M (telophase)

9 If a healthy cell passes the G1/S checkpoint:
it will enter the G0 stage of the cell cycle.
喵查答案：DNA will be replicated.
it will not divide.
it will proceed immediately to cytokinesis.
it will die.

10 Diploid cells are cells with ______ chromosomes.
a single set of
circular
喵查答案：two sets of
many sets of
three sets of

11 The process of splitting the cytoplasm, which separates one cell into two, is termed:
喵查答案：cytokinesis
mitosis
anaphase
diakinesis

12 The attachment point on the chromosome for spindle microtubules is the:
telomere
喵查答案：centromere
origin of replication
sister chromatid
sister chromatid

13 Cells with a single set of chromosomes are called diploid.
正确
喵查答案：错误

14 Generally, chromosomes of eukaryotes are circular.
正确
喵查答案：错误

15 Archaea are more closely related to eukaryotes than they are to eubacteria.
喵查答案：正确
错误

16 The prokaryotes include both the eubacteria and the archaea.
喵查答案：正确
错误

17 Errors in chromosome separation are rarely a problem for an organism.
正确
喵查答案：错误

Chapter 3 Basic Principles of Heredity

1 Which of the following statements is TRUE?
The genotype is the physical appearance of a trait.
Alleles, genes, and loci are different names for the same thing.
The phenotype of a dominant allele is never seen in the F1 progeny of a monohybrid cross.
喵查答案：A testcross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele.

2 In poodles, black is dominant to white.  A black poodle is crossed with a white poodle.  In a litter of four, all of the puppies are black.  What is the best conclusion?
The black poodle is definitely homozygous.
喵查答案：

The black poodle is probably homozygous

The black poodle is definitely heterozygous.

The black poodle is probably heterozygous.

3 In a cross between pure-breeding tall plants with pure-breeding short plants, all of the F1 are tall.  When these plants are allowed to fertilize themselves, the F2 plants occur in a ratio of 3 tall:1 short.  Which of the following is not a valid conclusion from these results?

The allele that produces the tall condition is dominant to the allele that produces the short condition.

The difference between tall and short stature in these lines is controlled by a single gene pair.

During production of gametes in F1 plants, the tall and short alleles segregate from each other equally into the gametes.
喵查答案：

The tall and short traits assort independently of each other in this cross.

Fertilization occurs randomly between gametes carrying the tall and short alleles.

4 In Mendel’s peas, yellow seeds are dominant to green.  A pure-breeding yellow plant is crossed with a pure-breeding green plant.  All of the offspring are yellow.  If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?
0%
25%
喵查答案：50%
75%
100%

5 Which of the following was not one of Mendel’s conclusions based on his monohybrid crosses?
喵查答案：Genes are carried on chromosomes.
Genes exist in pairs.
Members of a gene pair segregate equally into gametes. 

Genes behave as particles during inheritance.

One member of a gene pair can mask the expression of the other member.

6 In Mendel’s peas, purple flower color is dominant to white.  From which of the following descriptions can you not infer the genotype for the locus completely?
喵查答案：purple
white
pure-breeding purple
heterozygous

7

Genes come in different versions called:
喵查答案：alleles
loci
genotypes
chromosomes
genomes

8 The chi-square test is used to determine if observed outcomes are consistent with expected outcomes. 
喵查答案：正确
错误

9 The probability of a woman giving birth to three girls in a row is 1/8.
喵查答案：正确
错误

10 A testcross can be used to determine whether an individual is homozygous or heterozygous. 
喵查答案：正确
错误

11 The genotype is the physical appearance of a trait.
正确
喵查答案：错误

12 Mendel’s experiments involved both discrete and continuous genetic traits.
正确
喵查答案：错误

13 Branched diagrams are used for determining probabilities of various genotypes for genetic crosses involving more than one gene pair.
喵查答案：正确
错误

14 The principle of independent assortment can be demonstrated using a monohybrid cross.
正确
喵查答案：错误

15 A Mendelian dihybrid cross involves one gene and two different alleles.
正确
喵查答案：错误

16 The phenotype of a dominant allele is never seen in the F1 progeny of a monohybrid cross.
正确
喵查答案：错误

17 The probability of two or more independent events occurring together is calculated by multiplying their independent probabilities.
喵查答案：正确
错误

18 Alleles, genes, and loci are different names for the same thing. 
正确
喵查答案：错误

Chapter 4 Sex Determination and Sex-linked Characteristics

1 A Barr body is a(n):

gene on the X chromosome that is responsible for female development.

patch of cells that has a phenotype different from surrounding cells because of variable X inactivation

喵查答案：

 inactivated X chromosome, visible in the nucleus of a cell that is from a female mammal.

extra X chromosome in a cell that is the result of nondisjunction.

extra Y chromosome in a cell that is the result of nondisjunction.

2

If a female Drosophila that is heterozygous for a recessive X-linked mutation is crossed to a wild-type male, what proportion of female progeny will have the mutant phenotype?

100%
喵查答案：

0%

25%

50%

3

Red–green color blindness is X-linked recessive. A woman with normal color vision has a father who is color blind. The woman has a child with a man with normal color vision. Which phenotype is NOT expected?
喵查答案：

a color-blind female

a color-blind male

a noncolor-blind female

a noncolor-blind male
喵查答案：

a color-blind female

4

In Drosophila, flies that are XXY but have a normal diploid set of autosomes have been found. Such XXY chromosome constitutions have also been found in humans. The sex of such individuals is expected to be:

male in both Drosophila and humans.

female in both Drosophila and humans.

male in Drosophila but female in humans.
喵查答案：

female in Drosophila but male in humans.

intersexes in Drosophila and males in humans.

5

The sex determination system used by Drosophila is called:
喵查答案：

the X:A sex determination system.

the ZZ-ZW sex determination system.

the XX-XO sex determination system.

the XX-XY sex determination system.

genic sex detemination.

6

In species of birds, males are the homogametic sex and females the heterogametic sex. Which of the following statements is TRUE in this system of sex determination?
喵查答案：

The gender of the offspring is determined by the female parent.

Male offspring have a ZW chromosome constitution.

The gender of the offspring is determined by the male parent.

Female offspring have a ZZ chromosome constitution.

Female and male offspring have the same chromosome constitution.

7

In which of the following organisms is gender/sex determined by the temperature during embryonic development?

humans

mice

fruit flies

many snakes and birds
喵查答案：

many turtles and alligators

8

Which of the following chromosome constitutions would never lead to a viable human baby being born?

XXX

XYY

XO (O = the absence of a second chromosome)
喵查答案：

YY

XXY

9

What is the role of the SRY gene in humans?

It initiates the X inactivation process in females.

It is located on the X chromosome and causes the X to pair with the Y chromosome during male meiosis.
喵查答案：

It is located on the Y chromosome and initiates the developmental pathway toward the male phenotype.

It is located on an autosomal chromosome and represses expression of autosomal genes in order to balance their expression level with genes on the X chromosome.

10 Species in which individuals have only male or only female reproductive structures are called dioecious. 
喵查答案：正确
错误

11 A female with androgen insensitivity may have XY sex chromosomes rather than XX.
喵查答案：正确
错误

12 In species in which females are the homogametic sex, gender of offspring is determined by the male. 
喵查答案：正确
错误

13 Temperature during embryonic development determines sex in reptiles like turtles and alligators. 
喵查答案：正确
错误

14 The condition of having no X chromosomes, for example YO, is lethal in humans.
喵查答案：正确
错误

15 The condition XXXY is always lethal in humans. 
正确
喵查答案：错误

16 The cellular reason for X-inactivation is to reduce the amount of nondisjunction during meiosis.
正确
喵查答案：错误

17 Female mammals that are heterozygous for an X-linked gene have patches of cells that express one allele and patches of cells that express the other.
喵查答案：正确
错误

18 In humans SRY is the male determining gene.
喵查答案：正确
错误

19 The X and Y chromosomes are named after their characteristic shape.
正确
喵查答案：错误