1. A species of flowering plant includes plants with blooms that range from bright golden yellow to very pale yellow; no flowers carrying the yellow pigment allele appear white. The allele for yellow flower color:

a. must be a suppressor of another allele.
b. demonstrates incomplete penetrance.
c. demonstrates variable expressivity.
d. must be a modifier of another allele.
e. demonstrates variable penetrance.

2. Coat color in mice is determined by two alleles acting at a single locus: B is dominant and results in mice with black coats, and b is recessive and results in mice with white coats. In a litter of 12 mice, nine are black (B/â) and three are white (b/b). What is the penetrance of the B coat color allele?

a. zero
b. 25 percent
c. 50 percent
d. 75 percent
e. 100 percent

3. Semisterility in nearly 50 percent of the progeny they produce is often an indication that:

a. the parents are translocation heterozygotes.
b. both parents carry pericentric inversions.
c. both parents carry polytene chromosomes.
d. one of the parents carries a chromosomal deletion that removes a telomere.
e. one of the parents carries a chromosomal deletion that removes a chromosome's centromere.

4. A researcher is studying melanoma cells derived from a patient's skin tumor. He determines that all melanoma cells are 2n + 1, but the chromosome number in all normal skin cells is 2n. The 2n + 1 melanoma cells likely arose from:

a. mitotic nondisjunction.
b. meiotic nondisjunction.
c. mitotic recombination.
d. parthenogenesis.
e. colchicine treatment.

5. Why won't a balancer chromosome in Drosophila produce viable crossover products when paired with a wild-type chromosome?

a. Balancer chromosomes contain multiple inversions.
b. Balancer chromosomes contain multiple deletions.
c. Balancer chromosomes have no centromere.
d. Balancer chromosomes have no telomeres.
e. None of the answers is correct.

6. A doctor notes that a patient's genome contains 100 potentially harmful recessive mutations; however, the patient is heterozygous for all of the loci considered and thus does not demonstrate any abnormal phenotypes. The 100 recessive mutations the doctor discovered represent the patient's:

a. bivalents.
b. monosomy.
c.genetic load.
d. amphidiploidy.
e.nondisjunction.

7.The term describing the relationship between the number of copies of a gene and how much product is made from the gene is:

gene-dosage effect.
gene balance.
dosage compensation.
transcription.
aneuploidy.

8. The gene for upright ears in rabbits has two alleles. The E allele is dominant and results in upright ears, and the recessive e allele results in droopy ears. Of 100 rabbits surveyed, 87 had a genotype for upright ears (E/â). However, only 72 of these 87 rabbits had upright ears; the remaining 15 rabbits had completely droopy ears. This suggests that the allele for upright ears:

a. has incomplete penetrance.
b. has complete penetrance.
c. demonstrates variable expressivity.
d. is lethal.
e. is incompletely dominant.

9. A researcher has selfed an autotetraploid plant with the genotype D/D/d/d, and in the resulting progeny she observes a 35:1 phenotypic ratio. What can she conclude from this observation?

a. The progeny from this cross do not demonstrate a standard Mendelian phenotypic ratio.
b. In the 35:1 phenotypic ratio, the 1 represents the phenotype of the d/d/d/d progeny.
c. During meiosis in the D/D/d/d parent plant, it is likely that only bivalents, no quadrivalents or trivalents, formed.
d. It is likely that in this plant species, gametes associate with one another randomly.
e. All of the answers are correct.

10. A researcher is studying fur color in a new species of bats. He notices that fur color, which is due to the presence of a dominant allele (G), ranges from light gray to very dark gray. In addition, some bats that carry a G allele have no fur pigmentation whatsoever; their coats appear white. This is an example of:

a. only variable expressivity.
b. only incomplete penetrance.
c. both variable expressivity and incomplete penetrance.
d. recessive allele lethality.
e. pleiotropy.

amethystdinosaur303

**Please answer ALL 10 QUESTION**

1. A species of flowering plant includes plants with blooms that range from bright golden yellow to very pale yellow; no flowers carrying the yellow pigment allele appear white. The allele for yellow flower color:

a. must be a suppressor of another allele.

b. demonstrates incomplete penetrance.

c. demonstrates variable expressivity.

d. must be a modifier of another allele.

e. demonstrates variable penetrance.

2. Coat color in mice is determined by two alleles acting at a single locus: B is dominant and results in mice with black coats, and b is recessive and results in mice with white coats. In a litter of 12 mice, nine are black (B/â) and three are white (b/b). What is the penetrance of the B coat color allele?

a. zero

b. 25 percent

c. 50 percent

d. 75 percent

e. 100 percent

3. Semisterility in nearly 50 percent of the progeny they produce is often an indication that:

a. the parents are translocation heterozygotes.

b. both parents carry pericentric inversions.

c. both parents carry polytene chromosomes.

d. one of the parents carries a chromosomal deletion that removes a telomere.

e. one of the parents carries a chromosomal deletion that removes a chromosome's centromere.

4. A researcher is studying melanoma cells derived from a patient's skin tumor. He determines that all melanoma cells are 2n + 1, but the chromosome number in all normal skin cells is 2n. The 2n + 1 melanoma cells likely arose from:

a. mitotic nondisjunction.

b. meiotic nondisjunction.

c. mitotic recombination.

d. parthenogenesis.

e. colchicine treatment.

5. Why won't a balancer chromosome in Drosophila produce viable crossover products when paired with a wild-type chromosome?

a. Balancer chromosomes contain multiple inversions.

b. Balancer chromosomes contain multiple deletions.

c. Balancer chromosomes have no centromere.

d. Balancer chromosomes have no telomeres.

e. None of the answers is correct.

6. A doctor notes that a patient's genome contains 100 potentially harmful recessive mutations; however, the patient is heterozygous for all of the loci considered and thus does not demonstrate any abnormal phenotypes. The 100 recessive mutations the doctor discovered represent the patient's:

a. bivalents.

b. monosomy.

c.genetic load.

d. amphidiploidy.

e.nondisjunction.

7.The term describing the relationship between the number of copies of a gene and how much product is made from the gene is:

a. gene-dosage effect. gene balance.

b. dosage compensation.

c. transcription.

d. aneuploidy.

8. The gene for upright ears in rabbits has two alleles. The E allele is dominant and results in upright ears, and the recessive e allele results in droopy ears. Of 100 rabbits surveyed, 87 had a genotype for upright ears (E/â). However, only 72 of these 87 rabbits had upright ears; the remaining 15 rabbits had completely droopy ears. This suggests that the allele for upright ears:

a. has incomplete penetrance.

b. has complete penetrance.

c. demonstrates variable expressivity.

d. is lethal.

e. is incompletely dominant.

9. A researcher has selfed an autotetraploid plant with the genotype D/D/d/d, and in the resulting progeny she observes a 35:1 phenotypic ratio. What can she conclude from this observation?

a. The progeny from this cross do not demonstrate a standard Mendelian phenotypic ratio.

b. In the 35:1 phenotypic ratio, the 1 represents the phenotype of the d/d/d/d progeny.

c. During meiosis in the D/D/d/d parent plant, it is likely that only bivalents, no quadrivalents or trivalents, formed.

d. It is likely that in this plant species, gametes associate with one another randomly.

e. All of the answers are correct.

10. A researcher is studying fur color in a new species of bats. He notices that fur color, which is due to the presence of a dominant allele (G), ranges from light gray to very dark gray. In addition, some bats that carry a G allele have no fur pigmentation whatsoever; their coats appear white. This is an example of:

a. only variable expressivity.

b. only incomplete penetrance.

c. both variable expressivity and incomplete penetrance.

d. recessive allele lethality.

e. pleiotropy.

viridianlouse647

If an organismâs diploid chromosome number is 18, how many different possible combinations of homologous chromosomes lining up during meiosis exist for the eggs or sperm produced by that organism?

	A.	512
	B.	9
	C.	18
	D.	128
	E.	36

At the end of metaphase I, _______________ separate.

	A.	sister chromatids
	B.	germ cells
	C.	homologous chromosomes
	D.	haploid chromatids
	E.	centrioles

Mendel observed that dominant traits

	A.	are seen in all of the F1 hybrid pea plants in his experiments.
	B.	are expressed in all plants.
	C.	were absent in the F1 generation of pea plants that he used in his experiments.
	D.	were the only traits seen in the F2 generation of pea plants in his experiments.
	E.	are only expressed in hybrids.

Cytokinesis in plant cells differs from cytokinesis in animal cells because

	A.	there is no difference.
	B.	in plant cells, the cell plate must also divide into two parts.
	C.	the contractile protein, actin, is important only in plant cells.
	D.	plant cells have a rigid cell wall.
	E.	a contractile ring forms only in plant cells.

Sickle cell anemia is an example of what type of inheritance?

	A.	complete dominance
	B.	incomplete dominance
	C.	codominance
	D.	multiple alleles
	E.	recessive dominance

Which of the following statements is true:

	A.	The dominant allele is masked in homozygous dominant individuals.
	B.	With recessive genetic disorders, if both parents are carriers, the offspring will all be affected.
	C.	In carriers, the recessive allele causes an intermediate phenotype.
	D.	In recessive genetic disorders, the mother and/or father of an affected individual must also be affected.
	E.	With dominant genetic disorders, the mother and/or father of an affected individual must also be affected.

Skin cancers typically develop in the

	A.	upper layers of the epidermis.
	B.	lower layers of the dermis.
	C.	subcutaneous layer.
	D.	lower layers of the epidermis.
	E.	upper layers of the dermis.

Duchenne muscular dystrophy (MD) is inherited from an X-linked recessive allele. What is the probability that a son with Duchenne MD inherited this disease from his biological father?

	A.	1/2
	B.	0
	C.	1/16
	D.	1/4
	E.	1/8

The genetic makeup of a particular trait in an individual is its

	A.	genotype.
	B.	heterozygosity.
	C.	phenotype.
	D.	filial.
	E.	dominance.

What structure holds the sister chromatids to the spindle fibers?

	A.	chromatin
	B.	kinetochore
	C.	MPF
	D.	centromere
	E.	cyclin

If you view a cell in which the genetic material is beginning to be visible as separate bodies, and the nucleus has disappeared from view, you may surmise that the cells is in

	A.	telophase.
	B.	anaphase.
	C.	interphase.
	D.	metaphase.
	E.	prophase.

Gregor Mendel was successful in his analysis of the genetics of pea plants because

	A.	he examined and analyzed both the F1 and F2 generations.
	B.	he studied the parental plants to determine their differences.
	C.	he decided to only look at his results in an objective manner.
	D.	he studied a trait that had a strange inheritance pattern.
	E.	pea plants have genetics different from other organisms.

Tall corn plants (T) are dominant to dwarf plants (tt). Solid green leaves (G) are dominant to leaves with a white tip (gg). A cross between two corn plants yielded the following phenotypes: 51 tall plants with a white tip on their leaves; 43 dwarf plants with solid leaves; 48 dwarf plants with white tips on their leaves; 45 tall plants with solid leaves. What are the genotypes of the parents that produced these plants?

	A.	None of the above
	B.	TtGg x Ttgg
	C.	ttGG x TTgg
	D.	TtGg x TtGg
	E.	TtGg x ttgg

In humans, a gene that has been identified as causing a type of skin cancer is the

	A.	superwoman echidna.
	B.	mutant superman.
	C.	sonic hedgehog.
	D.	mutant mole rat.
	E.	superhero aardvark.

The segregation principle states that in sexually reproducing diploid organisms the two copies of each gene

	A.	segregate from each other during meiosis.
	B.	must always be the same allele.
	C.	separate from each other during mitosis.
	D.	will both wind up in either the sperm or egg.
	E.	move together as a unit during meiosis.

In what phases is the genetic material in the cell correctly referred to as chromatids?

	A.	metaphase and telophase
	B.	anaphase and metaphase
	C.	interphase and telophase
	D.	interphase and prophase
	E.	metaphase and prophase

Consider two traits for an organism, determined by two genes, each of which is governed by at least two alleles. In the case of a dihybrid individual, the gametes formed will be of either the parental type or the recombinant type. Recombinant type gametes are formed because of

	A.	the principle of dihybrids.
	B.	multiple alleles.
	C.	heterozygosity.
	D.	incomplete dominance.
	E.	independent assortment.

An allele is

	A.	an alternate form of a gene.
	B.	always recessive.
	C.	the main factor determining a trait.
	D.	always one of a pair.
	E.	the dominant form of a gene.

After the DNA is replicated, and it condenses in prophase, two identical rods of DNA are seen. These are

	A.	spindle fibers.
	B.	kinetochores.
	C.	chromatids.
	D.	chromatin.
	E.	centromeres.

Special cells found in the gonads that give rise to gametes upon division are called

	A.	egg cells.
	B.	somatic cells.
	C.	germ cells.
	D.	stem cells.
	E.	basal cells.

BIOL 2153 Lecture : Lecture 3

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