Download Exam 3 Multiple Choice Practice Questions

Exam 3 Multiple Choice Practice Questions
1. Which of the following describes an organism’s relative fitness?
a) survival
b) number of matings
c) adaptation to the environment
d) successful competition of resources
e) relative number of visible offspring
2. According to the Hardy-Weinberg principle,
a) the allele frequencies of a population should remain constant from one generation to the next if the
population is large and only sexual reproduction is involved
b)only natural selection, resulting in unequal reproductive success, will cause evolution
c) the square root of the frequency of individuals showing the dominant trait will equal the frequency of p
d) p and q can only be determined for a population that is not evolving
e) all of the above are correct
3) The breeding of plants and animals for particular traits by humans is called _______.
a) natural selection
b) sexual recombination
c) founder effect
d) artificial selection
e) neutral variation
4) In a certain species of plant, the alleles A, B, and C are completely dominant to the alleles a, b, and c. A
plant with genotype AABbcc will have the same phenotype as a plant with the genotype…
a) Aabbcc
b) aabbcc
c) AaBBcc
d) AABBCc
e) none of the above
5) If a population has the following genotype frequencies, AA = 0.42, Aa= 0.46, and aa= 0.12m what are
the allele frequencies?
a) A = 0.42 a= 0.12
b) A = 0.6 a= 0.4
c) A = 0.65 a =0.35
d) A = 0.76 a = 0.24
e) A = 0.88 a = 0.12
6) A scientist observes that the height of a certain species of asters decreases as the altitude on a
mountainside increases. She gathers seeds from samples at various altitudes, plants them in a uniform
environment, and measures the height of the new plants. All of her experimental asters grow to
approximately the same height. From this she concludes that:
a) height is not a quantitative trait
b) the cline she observed was due to genetic variations
c) the differences in the parent plants’ heights were due to directional selection
d) the height variation she initially observed was an example of nongenetic environmental influence
e) stabilizing selection was responsible for height differences in the parent plants
7. The greatest source of genetic variation in plant and animal populations is from
a) mutations
b) sexual reproduction
c) selection
d) geographic variation
e) recessive masking in heterozygote
8. Mice that are homozygous for a lethal recessive allele die shortly after birth. In a large breeding colony of
mice, you find that a surprising 5% of all newborns die from this trait. In checking lab records, you discover
that the same proportion of offspring have been dying from this trait in this colony for the past three years.
(Mice breed several times a year and have large litters.) How might you explain the persistence of this lethal
allele at such a high frequency?
a) homozygous recessive mice have a reproductive advantage
b) a large mutation rate keeps producing this lethal allele
c) there is some sort of heterozygote advantage and perhaps selection against the homozygous dominant trait
d) genetic drift has kept the recessive allele at this high frequency in the population
e) since this is a diploid species, the recessive allele cannot be selected against when it is in the heterozygote.
9. In a population with two alleles, B and b, the allele frequency of b is 0.4. What would be the frequency of
the heterozygotes if the population is in Hardy-Weinberg Equilibrium?
a) 0.16
b) 0.24
c) 0.48
d) 0.6
e) you cannot tell from this information
10. What is a karyotype?
a) a genotype of an individual
b) a pictorial display of an individual’s chromosomes
c) a blood type determination of an individual
d) a unique combination of chromosomes found in a gamete
e) a species-specific diploid number of chromosomes
11. What are autosomes?
a) sex chromosomes
b) chromosomes that occur singly
c) chromosomal abnormalities that result in genetic defects
d) chromosomes found in mitochondria and chloroplasts
e) none of the above
12. During the first meiotic division (meiosis I),
a) homologous chromosomes separate
b) the chromosome number is reduced in half
c) crossing over between nonsister chromatids occurs
d) paternal and maternal chromosomes assort randomly
e) all of the above occur
13. A cell with a diploid number of 6 could produce gametes with how many different combinations of
maternal and paternal chromosomes?
a) 6
b) 8
c) 12
d) 64
e) 128
14. In a population that is in Hardy-Weinberg equilibrium for two alleles, C and c, 16% of the population
show a recessive trait. Assuming C is dominant to c, what percent show the dominant trait?
a) 36%
b) 48%
c) 60%
d) 84%
e) 96%
15. Mutations are rarely a direct source for microevolution in eukaryotes because
a) they are most often harmful and do not get passed on
b) they do not directly produce most of the genetic variation present in a diploid population
c) they occur very rarely
d) they are only passed on when they occur in gametes
e) all of the above
16. In a study of a population of field mice, you find that 48% of the mice have a coat color that indicates
that they are heterozygous for a particular gene. What would be the frequency of the dominant allele in this
population?
a) 0.24
b) 0.48
c) 0.50
d) 0.60
e) you cannot estimate allele frequency from this information
17. An individual with the genotype of AABbCcDD can make how many different kinds of gametes?
a) 2
b) 4
c) 8
d) 16
e) 32
18. Natural selection acts most directly on…
a) phenotypes
b) genotypes
c) mutations
d) heterozygotes
e) homozygotes
19. Flower color is snapdragons is an example of incomplete dominance. When a red-flowered plant is
crossed with a white-flowered plant, the F1 generation has pink flowers. If a pink-flowered plant is crossed
with a white-flowered plant, the progeny plants will be:
a) 100% pink
b) 100% white
c) 50% pink and 50% white
d) 25% red, 50% pink, 25% white
e) 25% white and 75% pink
20. The DNA content of a diploid cell is measured in the G1 phase. After meiosis I, the DNA content of
one of the two cells produced would be
a) equal to that of the G1 cell
b) twice that of the G1 cell
c) one-half that of the G1 cell
d) one-fourth that of the G1 cell
e) impossible to estimate due to independent assortment of homologous chromosomes
21. In most fungi and some protists,
a) the zygote is the only haploid stage
b) gametes are formed by meiosis
c) the multicellular organism is haploid
d) the gametophyte generation produces gametes by mitosis
e) reproduction is exclusively asexual
22. Meiosis II is similar to mitosis because
a) sister chromatids separate
b) homologous chromosomes separate
c) DNA replication precedes the division
d) they both take the same amount of time
e) haploid cells are almost always produced
23. Pairs of homologous chromosomes
a) have identical DNA sequences in their genes
b) have genes for the same characters at the same loci
c) are found in gametes
d) separate in meiosis II
e) have all of the above characteristics
24. asexual reproduction of a diploid organism would
a) be impossible
b) involve meiosis
c) produce identical offspring
d) show variation among sibling offspring
e) involve spores produced by meiosis
25. How many chromatids are present in metaphase II in a cell undergoing meiosis from an organism in
which 2n= 24?
a) 12
b) 24
c) 36
d) 48
e) 96
26. Which of the following would not be considered a haploid cell?
a) daughter cell after meiosis II
b) gamete
c) daughter cell after mitosis in gametophyte generation of a plant
d) cell in prophase I
e) cell in prophase II
27. Which of the following is not true of homologous chromosomes?
a) they behave independently in mitosis
b) they synapse during the S phase of meiosis
c) they travel together to the metaphase plate in meiosis I
d) they are held together during synapsis by a synaptonemal complex
e) crossing over between nonsister chromatids of homologous chromosomes is indicated by the presence of
chiasmata
28. Which of the following human diseases is inherited as a simple recessive trait?
a) Tay-Sachs disease
b) cancer
c) diabetes
d) Alzheimer’s disease
e) cardiovascular disease
29. A 1:1 phenotypic ratio in a testcross indicates that
a) the alleles are dominant
b) one parent must have been homozygous dominant
c) the dominant phenotype parent was a heterozygote
d) the alleles segregated independently
e) the alleles are codominant
30. A mother with type B blood has two children, one with type A blood and one with type O blood. Her
husband has type O blood. Which of the following could you conclude from this information?
a) the husband could not have fathered either child
b) the husband could have fathered both children
c) the husband must be the father of the child with type O blood and could be the father of the type A child
d) the husband could be the father of the child with type O blood, but not the type A child
e) neither the mother nor the husband could be the biological parent of the type A child
31. In pea plants, tall (T) is dominant to dwarf (t) and yellow (Y) is dominant to green (y). In a cross of truebreeding tall yellow peas x dwarf green peas, what proportion of the progeny are tall with yellow peas?
a) 0%
b) 25%
c) 50%
d) 75%
e) 100%
32. In a cross that follows a single trait, if a homozygous dominant is crossed with a heterozygote for a
given trait, the offspring will be:
a) all of the dominant phenotype
b) ¼ of the recessive phenotype
c) all homozygous dominant
d) all homozygous recessive
e) present in a 9:3:3:1 ratio
33. A dominant allele P causes the production of purple pigment; pp individuals are white. A dominant
allele C is also required for color production; cc in dividuals are all white. What proportion of offspring will
be purple from a ppCc x PpCc cross?
a) 1/8
b) 3/8
c) ½
d) ¾
e) none
34. Sex-linked traits
a) are carried on an autosome but expressed only in males
b) are coded for by genes located on a sex chromosome
c) are found in only one or the other sex, depending on the sex determination system of the species
d) are always inherited from the mother in mammals and fruit flies
e) depend on whether the gene was inherited from the mother or the father
35. A wild type is
a) the phenotype found most commonly in nature
b) the dominant allele
c) designated by a small letter if it is recessive or a capital letter if it is dominant
d) a trait found on the X chromosome
e) your basic party animal