Characters that show a continuous range of variation

12 Jun Characters that show a continuous range of variation

Question
1.

Characters that show a continuous range of variation, such as height and eye color, usually are controlled:

A) by a single gene with two alleles that are codominant.

B) by many genes with an additive effect.

C) by epistatic interactions between two genes.

D) mainly by the environment, with only a small genetic component.

2.

In humans, red-green colorblindness is inherited as a sex-linked recessive trait. In order for a woman to be red-green colorblind, which of the following statements must be true.

A) Her mother must be red-green colorblind.

B) All of her brothers must be red-green colorblind.

C) Her father must be red-green colorblind.

D) All of the above statements must be true if a woman is red-green colorblind.

3.

The x-ray crystallography data collected by Rosalind Franklin suggested to Watson and Crick that the:

A) structure of DNA is a double helix.

B) two strands of the DNA molecule are joined by hydrogen bonds between the bases.

C) four bases within DNA pair in a specific way.

D) two strands of the DNA molecule are joined by covalent bonds between the bases.

4.

In the genetic code, _________ one amino acid.

A) one nucleotide specifies

B) two nucleotides specify

C) three nucleotides specify

D) four nucleotides specify

5.

During Meiosis I, a homologous pair of chromosomes may not separate, resulting in daughter cells that have extra chromosomes or are missing chromosomes. This can lead to genetic disorders, including Down Syndrome. This phenomenon is called:

A) independent assortment.

B) nondisjunction.

C) segregation.

D) crossing over.

6.

You are a human geneticist studying the incidence of retinitis pigmentosa in the residents of Tristan de Cunha, a group of small islands in the middle of the southern Atlantic Ocean. The allele for retinitis pigmentosa, which causes a form of blindness, is inherited as an autosomal recessive. You have determined that the frequency of this allele (r) in the population is 0.4 (40%). Using the principles of the Hardy-Weinberg rule, you would estimate the frequency of individuals who are heterozygous for this allele (Rr) in the population to be:

A) 0.16 (16%)

B) 0.24 (24%)

C) 0.36 (36%)

D) 0.48 (48%)

7.

Natural selection acts at the level of the:

A) phenotype.

B) gene.

C) population.

D) nucleotide.

8.

You are working with pea plants, trying to recreate the experiments that Mendel performed. You are doing a dihybrid cross with a plant that is heterozygous for both seed shape and seed color, with the genotype RrYy. Which allelic combinations would you expect to find in the gametes produced by this plant?

A) This plant would produce only RY and ry gametes.

B) This plant would produce only RrYy gametes.

C) This plant would produce RY, Ry, rY, and ry gametes.

D) You cannot determine which gametes this plant can produce without knowing the genotypes of its parents.

9.

Biochemist Erwin Chargaff found that in DNA there is a special relationship between the four bases that we now call Chargaff’s rule. His observation was that, in an organism’s genome the:

A) percentage of A nucleotides = the percentage of T nucleotides, and the percentage of C nucleotides = the percentage of G nucleotides.

B) four bases all occur in an equal frequency (25%) within each organism.

C) percentage of A nucleotides = the percentage of G nucleotides, and the percentage of C nucleotides = the percentage of T nucleotides.

D) genetic material is composed of proteins, not DNA.

10.

During DNA replication:

A) each strand of the double helix acts as a template for the synthesis of a new strand.

B) the enzyme DNA polymerase adds nucleotides to the strand being synthesized.

C) the bases A,C,G and T are required.

D) All of the above are true of DNA replication.

11.

During translation, amino acids are joined by peptide bonds to make polypeptides. The formation of these peptide bonds is catalyzed by:

A) DNA.

B) mRNA.

C) tRNA.

D) rRNA.

12.

If an allele (R) at a gene with two alleles shows complete dominance, individuals with the genotypes ______ will have the same phenotype.

A) RR and rr.

B) RR and Rr

C) Rr and rr

D) Each of the three possible genotypes will have a different phenotype.

13.

The arms of a human and the wing of a bat are _________________ structures, composed of the same bones that have been modified for different functions.

A) analogous

B) vestigial

C) homologous

D) convergent

14.

Xeroderma pigmentosum is an autosomal recessive genetic disorder. People who are homozygous for the disease-causing allele have skin that is damaged by exposure to ultraviolet radiation; this can lead to skin cancer at an early age. The mutation that causes this disorder is in a gene that functions:

A) to repair DNA by excising (removing) nucleotides damaged by UV light.

B) in lysosomes, to break down lipids that otherwise accumulate in the nervous system.

C) to produce the UV blocking pigment melanin in the skin cells

D) in red blood cells to carry oxygen to the skin.

15.

The Amish are a religious sect descended from a small group of colonists who came to the United States over 200 years ago. Their religious beliefs have kept them isolated from society. The Amish have a much higher than average incidence of both polydactyly (extra fingers and toes) and dwarfism in their communities. This is most likely explained by:

A) inheritance of acquired characters.

B) the founder effect.

C) disruptive selection.

D) natural selection.

16.

In the structure of DNA that Watson and Crick proposed, the sides of the “ladder” of the DNA molecule are always the same distance apart, making the molecule a constant width. This occurs because when the bases hydrogen bond to form the rungs of the “ladder”, a:

A) purine always pairs with a pyrimidine.

B) purine always pairs with a purine.

C) pyrimidine always pairs with a pyrmidine.

D) The structure of the double helix is not determined by how the bases pair.

17.

The RNA transcript of DNA that travels to the cytoplasm, carrying the instructions to make a protein, is called:

A) rRNA.

B) tRNA.

C) mRNA.

D) RNA polymerase.

18.

When DNA is replicated, the error rate is approximately one error for every 10,000 nucleotides copied. However, that error rate is reduced to only 1 error for every 1 billion nucleotides. The DNA sequence is “corrected” by:

A) repeating S phase to see if the error rate is lower the second time around.

B) enzymes that proofread the DNA and repair errors.

C) messenger RNA during the process of transcription.

D) Any errors made during DNA replication cannot be corrected. If errors are detected after S phase, the cell is destroyed.

19.

Mendel’s principle of segregation says that:

A) when gametes are formed, each gamete receives only one allele for a particular gene.

B) some genes are dominant to others.

C) a testcross must be used to determine the genotype of an organism with a dominant phenotype.

D) all of the above

20.

Tay-Sachs disease is lethal before reproductive age, but the allele persists in Louisiana French Canadians because:

A) it is a dominant allele.

B) new mutations causing this disease are common in that population.

C) it is not expressed in the phenotype of heterozygous individuals.

D) the disease is contagious and can be transmitted by nonheritable means.

21.

Physical features that are similar in organisms which are not closely related to each other are most likely a result of ____________. A good example of this is the similarities seen between some marsupial and placental mammals.

A) natural selection.

B) adaptation to similar environments

C) convergent evolution

D) All of the above phrases can be used to correctly fill this blank.

22.

In humans, which of the following sex chromosome compliments could be found in males?

A) XY

B) XX

C) Y

23.

The proteins that are associated with eukaryotic chromosomes:

A) help to package the DNA within the nucleus.

B) are involved in gene expression, through binding with the DNA.

C) may be replicating or transcribing the DNA.

D) All of these are true of proteins that are associated with eukaryotic chromosomes.

24.

A sequence of DNA nucleotides that contains the information to produce a single protein is a(n):

A) codon.

B) gene.

C) polypeptide.

D) anticodon.

25.

Which one of the following statements about mutations is true?

A) Mutations provide the basis for genetic variability in all organisms.

B) Mutations that occur in any cell in the body are heritable.

C) Mutations that occur during replication cannot be repaired.

D) Mutations in the DNA are always harmful.

26.

In cats, short fur (L) is a completely dominant trait; long fur (l) is recessive. You are breeding cats and you want to see if your short-haired cat is homozygous dominant or heterozygous for the gene that determines the length of its fur. What would be the genotype of the cat that you would mate it with to determine its genotype for fur length?

A) LL

B) Ll

C) ll

D) You do not need to do a cross to determine this. You can tell simply by observing the cat’s phenotype.

27.

The gypsy moth was introduced from Europe to the United States in the late 1860s, in the town of Medford, Massachusetts. Since that time, it has continued to spread across the northeastern part of the country. This species poses a serious economic threat because in years of high population density its caterpillars defoliate trees, leaving the trees susceptible to disease or death. Controlling this species is a high priority for both federal and state governments. Female gypsy moths cannot fly, but secrete pheromones to signal to the male moths where they are. The male moths follow these chemical signals to the females, and mate with them. A synthetic version of this hormone has been made and traps are baited with it, luring the male moths to their deaths. These pheromones would best be described as a ____________ reproductive isolating mechanism.

A) temporal

B) behavioral

C) mechanical

D) habitat

28.

Which one of the following is an example of macroevolution?

A) The appearance of an albino squirrel in the population of gray squirrels on the Penn State’s campus.

B) The increase in size of white-tailed deer as you go from the southern to the northern United States.

C) A kitten with long hair in a litter of kittens whose parents both had short hair.

D) The evolution of flight in a group of mammals, the bats.

29.

Genetics Problems – Problem I. In mice, yellow coat color is inherited as an autosomal trait that shows complete dominance; a mouse with gray fur is homozygous for the recessive allele (g). However, mice that are homozygous for the dominant yellow allele (G) die on the sixth day of gestation, so they are never born. You mate a yellow female mouse with a yellow male mouse. Construct a Punnett Square in order to answer the questions below. What is the genotype of the parent mice?

A) GG

B) Gg

C) gg

D) The parents can be either GG or Gg

30.

What proportion of the mice in the litter will be yellow?

A) 1/4 (25%)

B) 1/3 (33%)

C) 2/3 (67%)

D) 3/4 (75%)

31.

What will the genotype of these yellow offspring be?

A) GG

B) Gg

C) gg

D) Yellow offspring can be either GG or Gg.

32.

What proportion of the mice in the litter will be gray?

A) 1/4 (25%)

B) 1/3 (33%)

C) 2/3 (67%)

D) 3/4 (75%)

33.

Genetics Problems – Problem II. The ichthyoses are a family of genetic skin diseases characterized by excessively dry, thickened, scaling skin. Ichthyosis, often called “fish scale” disease, is disfiguring, often disabling and in some cases life threatening. The most common type of ichthyosis affects approximately one of every 6000 people and is inherited as a sex-linked recessive disorder in humans. A woman with normal skin who is a carrier of the ichthyosis allele (f) marries a man who has normal skin (F). Based upon this information, construct a Punnett Square, then answer the questions that follow. What is the probability that they will have a child with ichthyosis?

A) 25% (1/4)

B) 50% (1/2)

C) 75% (3/4)

D) 100%

34.

The woman becomes pregnant and has a karyotype analysis done for her fetus. The couple finds out that the baby is a boy. What is the probability that their son will have ichthyosis?

A) 0%

B) 25% (1/4)

C) 50% (1/2)

D) 100%

35.

If the child is a daughter, what is the probability that she will have ichthyosis?

A) O%

B) 25% (1/4)

C) 50% (1/2)

D) 100%

36.

What is the probability that they will have a child who has normal skin but is a carrier of the ichthyosis allele?

A) 0%

B) 25% (1/4)

C) 50% (1/2)

D) 75% (3/4)