BIOL-1103 Test #2 Study Guide (GSU Dr. Chowdhury)

A thoroughbred racehorse could have at most __________ alleles of the same gene.

2

Consider a gene with two alleles that show complete dominance. When two heterozygotes for this genebreed, they have a 25 percent chance of producing a homozygous recessive offspring. The next time thesetwo individuals breed, what are the chances that they will once again have a homozygous recessiveprogeny?

25 percent

A pea plant that is heterozygous for the flower color gene makes gametes. What is theprobability that a specific gamete contains the recessive allele for flower color?

50 percent

Suppose D were dominant and d were recessive, and you could label the D allele in theP generation with a radioactive substance that could be inherited over several generations.You create hybrids by mating your radioactive DD individuals to dd individuals. Finally, you cross twoF1 individuals (with the Dd genotype). In 1,000 offspring, how many would you predict would beradioactive?

750

Would it be necessary to have both the genotype and phenotype for an organism if you are attempting to predict the inheritance pattern for a trait, such as hair color, in offspring?

No; knowing the genotype will indicate the phenotype.

Why did Mendel analyze thousands of plants while conducting his research?

The likelihood of seeing a clear pattern is higher with a larger data set.

An allele is

a version of a gene.

Which of the following choices represents the genotype of an individual diploid organism? a. BbCCdd b. BCd c. bcd d. BbCd

a. BbCCdd

Which of the following statements explains how genetically identical plant clones can exhibit dramatic phenotypic variation? a. Environmental conditions under which plants are grown can cause variations in phenotypes. b. Plants undergo mutations to adapt to temperature extremes. c. Plants are able to shut off genes that are not adaptive in their current environment. d. Genetically identical plants cannot have different phenotypes.

a. Environmental conditions under which plants are grown can cause variations in phenotypes.

Which of the following represents all of the possible gametes that can be formed by an individual with thegenetic makeup FfGgHH? a. FGH, FgH, fGH, fgH b. Ff, Gg, HH c. FG, FH, Fg, fH, fG, fg, GH, gH d. FfGhHH, FFGGHH, ffgghh

a. FGH, FgH, fGH, fgH

Which of the following did Gregor Mendel notice in garden peas? a. Some plants always produced offspring with flowers that were the same color as theparent plant's flowers. b. The first generation from a genetic cross of true-breeding plants always producedoffspring that were intermediate in their phenotype and did not look like either parent. c. Garden peas always produce a variety of phenotypes in their offspring, which result fromfrequent mutations. d. Any individual pea plant carries at least three different alleles for flower color.

a. Some plants always produced offspring with flowers that were the same color as the parent plant's flowers.

In which of the following situations would it become nearly impossible to predict the phenotype of anindividual with a known genotype? a. The environment affects the phenotype. b. The genotype of the parents is unknown. c. The genotype of offspring is unknown. d. You should always be able to predict the phenotype if you know the genotype.

a. The environment affects the phenotype.

Which of the following did Mendel use to help him form the law of independent assortment? a. dihybrid crosses between pea plants b. monohybrid crosses between pea plants c. traits that were codominant d. traits with incomplete dominance

a. dihybrid crosses between pea plants

The coat color in a Siamese cat is determined by a temperature-sensitive allele that allows the brownishpigment melanin to be produced in extremities of the body. What might explain this phenomenon? a. Melanin appears darker in extremities because less light is reflected. b. Alleles are used to produce proteins that function best in specific temperature ranges. c. Siamese cats evolved in warm climates and did not need melanin. d. Extremities in a cat are more prone to damage from sunlight.

b. Alleles are used to produce proteins that function best in specific temperature ranges.

The leaf color of a certain plant is controlled by one gene. For that gene, the allele G = orange and g =green. You have a plant with orange leaves, but do not know whether that plant's genotype is GG or Gg.Which of the following would help you determine the plant's genotype? a. Cross the plant to another plant with orange leaves. b. Cross the plant to a plant with green leaves. c. Cross two true-breeding, orange-leaved plants to each other and then cross one of theiroffspring to the plant with the unknown genotype. d. Change the environment in which the plant grows to find the conditions that cause the leaves to produce the orange color.

b. Cross the plant to a plant with green leaves.

In a particular plant, two genes control leaf shape and color. Round leaves (R) aredominant to jagged leaves (r). Yellow fruits (Y) are dominant to white fruits (y). A true-breedinground-leaved, yellow-fruited plant is mated with a jagged-leaved, white-fruited plant.What are the genotypes of the plants involved in this cross? a. RRYY x RRYY b. RRYY x rryy c. RrYy x RrYy d. cannot determine from the information given

b. RRYY x rryy

Two organisms that are true-breeding for a certain genetic characteristic are mated andtheir offspring analyzed. Which of the following statements about this situation is true? a. Both parents are heterozygotes. b. The offspring are either 100 percent homozygotes or 100 percent heterozygotes. c. The offspring represent the P generation. d. The gametes produced by the offspring will carry two alleles for this gene.

b. The offspring are either 100 percent homozygotes or 100 percent heterozygotes.

If you compare a sperm cell in a human to a skin cell from the same individual, which of the following differences would you expect to find? a. The sperm cell would contain four alleles for a given gene; the skin cell would contain two alleles. b. The sperm cell would contain only one allele for a given gene; the skin cell would contain two alleles. c. Both sperm and skin cells may carry different alleles for an individual gene. d. Both sperm and skin cells would contain 46 chromosomes found as homologous pairs.

b. The sperm cell would contain only one allele for a given gene; the skin cell would contain two alleles.

Which of the following expresses Mendel's law of segregation? a. All dominant alleles of different genes divide into different cells from the recessive alleles. b. Two alleles of a gene separate during meiosis and end up in different gametes. c. When gametes form, the genes originally from one parent all end up in different gametesfrom the genes originally from the other parent. d. Gametes with recessive alleles will fuse only with each other.

b. Two alleles of a gene separate during meiosis and end up in different gametes.

Which of the following statements is NOT true? a. Two organisms with the same phenotype may have different genotypes. b. Two organisms with the same genotype are homozygous. c. A heterozygous organism may have the same phenotype as a homozygous organism. d. A heterozygous organism has fewer alleles for a given gene than a homozygous organism.

b. Two organisms with the same genotype are homozygous.

In a genetic cross of Gg with Gg guinea pigs, none of the four offspring were gg. This a. disproves Mendel's law of independent assortment. b. neither supports nor disproves Mendel's law of independent assortment. c. supports Mendel's law of independent assortment. d. supports Mendel's law of segregation.

b. neither supports nor disproves Mendel's law of independent assortment.

Which of the following is true for mutations? a. Mutations will affect the genotype without affecting the phenotype. b. Mutations will affect the phenotype without affecting the genotype. c. Mutations will affect the genotype, which may affect the phenotype. d. Mutations will affect the phenotype, which may affect the genotype.

c. Mutations will affect the genotype, which may affect the phenotype.

Which of the following statements is a basic summary of one of Mendel's laws? a. All beneficial human genetic traits are dominant and harmful traits are recessive. b. The pattern of inherited characteristics of organisms is not predictable. c. The separation of alleles for one gene does not affect the separation of alleles for other genes. d. Recessive alleles cause the death of the gamete.

c. The separation of alleles for one gene does not affect the separation of alleles for other genes.

Which of the following might explain how two separate genes control a single trait? a. Both genes have the same alleles. b. One gene functions better at higher temperatures. c. There are two genes to control two separate steps in a pathway. d. Two genes cannot control a single trait.

c. There are two genes to control two separate steps in a pathway.

Which of the following statements is true of Mendel's laws? a. They are less accurate than Punnett square results. b. They are useful only in unusual situations. c. They correctly explain how genes are inherited. d. They correctly predict the phenotype of an organism.

c. They correctly explain how genes are inherited.

Which of the following does NOT represent a phenotype? a. a person's susceptibility to Addison's disease b. the height of a draft horse c. the alleles in a mouse that control hair color d. the extent to which an individual is shy

c. the alleles in a mouse that control hair color

Which of the following is the mechanism described by Mendel that results in a new combination ofalleles in a pea plant seed? a. the mutation of multiple alleles during mitosis b. the mutation of multiple alleles during meiosis c. the separation of alleles for two different genes during meiosis d. the separation of alleles for a single gene during meiosis

c. the separation of alleles for two different genes during meiosis

If two different alleles for the same trait have an equal effect on the phenotype, the alleles are

codominant.

Most human genetic characters are

controlled by more than one gene.

Which of the following statements is NOT true? a. Traits that are determined by the effect of more than one gene are known as polygenic. b. Environmental factors can alter the effects of genes. c. Most traits are under the control of more than one gene. d. A genotype is always expressed in the phenotype.

d. A genotype is always expressed in the phenotype.

Which of the following statements regarding genes is NOT true? a. Genes are located on chromosomes. b. Genes consist of a long sequence of DNA. c. Genes are the basic unit of information affecting a genetic trait. d. In sexually reproducing species, each cell contains a single copy of every gene.

d. In sexually reproducing species, each cell contains a single copy of every gene.

When Mendel proposed the law of segregation, which of the following pieces of information did he NOT have? a. data on the outcomes of crossing two true-breeding pea plants b. ratios to predict the outcome of crossing two heterozygous pea plants c. a prediction for how a single trait is inherited d. knowledge of the location of the alleles for flower color

d. knowledge of the location of the alleles for flower color

Two genes control fur color in Labrador retrievers. The first gene determines whether the pigment to bedeposited in the hairs will be black or brown. The second gene determines whether the pigments are putinto the dog's hairs at all. A dog homozygous for the recessive allele of this second gene will be yellowbecause no pigment is deposited in its hairs. This is an example of

epistasis

We need a hammer to pound nails into a board. Even if we have the nails, we cannot pound them withoutfirst getting hold of a hammer. This is similar to the genetic relationship known as

epistasis.

Mendel used __________ as his research organism to study patterns of genetic inheritance.

garden peas

Feather color in a certain species of bird is controlled by a pair of alleles that exhibit incompletedominance. If birds that are homozygous for one allele are black and birds that are homozygous for theother allele are white, then heterozygous birds would be

gray.

A chestnut-colored horse is mated with a cremello (cream-colored) horse. Over a 10-yearperiod, all of their offspring are palominos. This pattern of inheritance is best explained by

incomplete dominance.

Mendel's laws of segregation and independent assortment both have their biological basis in events that take place during

meiosis

One of the first medical tests a newborn receives determines if the child has phenylketonuria (PKU). PKUis the result of a mutation in a single gene that causes mental retardation and a host of other phenotypes(light hair and skin color, eczema, and a "mousy" smell). By detecting PKU early, doctors are able toreduce the effect of this condition with a modified diet. PKU is an example of

pleiotropy.

The observation that individuals afflicted with albinism also always have vision problems isan example of

pleiotropy.

A Punnett square is used to

predict the outcome of a genetic cross.

In Mendel's controlled mating experiments the individuals produced by crossing two true-breeding parents are referred to as

the F1 generation.

The pleiotropy that occurs when a single gene controls multiple skeletal traits in dogs, such as leg bonelength and skull size, may be explained because

the skeletal traits are related in the overall function of the dog.

Mendel's manuscript discussing his pea-breeding results is considered one of the two most important scientific papers of the nineteenth century because he was the first to explain how

traits are passed from one generation to the next.

What is the smallest number of traits that are needed to test Mendel's law of independent assortment?

two