AP Bio Semester 1

Gregor Mendel's pioneering genetic experiments with pea plants occurred before the discovery oT the structure and function of chromosomes. Which of the following observations about inheritance in pea plants could be explained only after the discovery That genes may be linked chromosome?

Most offspring of a given cross have a combination of traits that is identical to that of either one parent the other.

A genetic counselor is consulted by a young man who is worried about developing Huntington's disease, an inherited disorder caused by a dominant allele of a single gene. The young man explains that his cousin was recently diagnosed with Huntington's disease, and the news has caused him to consider his own risk of developing the disorder. Which of the following questions will best help the genetic counselor to evaluate the risk of the young man developing Huntington's disease and transmitting it to his children?

(B) Were your parents or grandparents ever diagnosed with Huntington's disease?

In garden peas, a. single gene controls stem length. The recesslve allele (O produces short stems v when homozygous. The dominant allele (Ti produces long stems. A short-stemmed plant is crossed with a heterozygous long-stemmed plant. Which of the following represents the expected phenotypes of the offspring and the ratio in which they will occur?

1 long-stemmed plant : 1 short-stemmed plant

A couple has 5 children,all sons.If the woman gives birth to a sixth child,what is the probability that the sixth child will be a son?

1/2

if three children are born to Matthew and Jane, what are the chances that the first two children will not express the trait but that the third will be an achondroplastic dwarf

1/8

An African violet grower observes that genetically identical African plants... Which of the following best explains the differences in flower color of the African violets in the greenhouse?

An enzyme responsible for the flower color does not fold correctly in cooler temperatures, and the greenhouse is warmest in the center

Trinosomy 21 is a condition in which a child is born with an extra chromosome in pair 21. ers assessed the frequency of children born with trisomy 21 by age of the mothers at birth age) and primary cause of the error leading to trisomy 21...which of the following is most likely the primary causes trisonomy 21 births in the selected maternal age-groups?

At older maternal ages, the incidence of errors in meiosis during egg production increases, which leads to an increase in nondisjunction,

In the pedigree above, squares represent males and circles represent females. Individuals who express a particular trait are represented by shaded figures. Which of the following patterns of inheritance best explains the transmission of the trait?

Autosomal dominant

A student in a biology class crossed a male Drosophila melanogaster having a gray body and long wings with a female D. melanogaster having a black body and apterous wings. The following distribution of traits was observed in the offspring. Which of the following is supported by the data?

Genes for the two traits located close together on the same chromosome, and crossing over occurred between the two gene loci

n sweet pea plants, purple flower color is dominant over red flower color and long pollen grain {-shape is dominant over round pollen grain shape. Two sweet pea plants that are hgerozygous for both flower color and pollen grain shape are crossed with one another. A geneticist is surprised to observe that there are far fewer roum rnRm offs[Mg and lon red offspring than were predicted by the 9 3 3 1 expected phenotypic ratio. Which of the following statements provides the most reasonable prediction to account for the deviation from the expected results?

In sweet pea plants. The gene for flower color and the gene for pollen grain shape are genetically linked.

Australian dragon lizards have a ZW sex-determination system. The male genotype is homogametic (ZZ), and the female genotype is heterogametic (ZW). However, all §ggs incubatedat tem Ftures above 32 ° C tend to lop into feaa wwch of the following best explains how the development of phenotypic female Australian dragonlizards with a ZZ genotype occurs when incubation temperatures are above 32'C?

Incubation temperatures above 32 inhibit the genes on the Z chromosome that produce proteins necessary for male development

Based on the data in Table I, which of the following best explains why there are no individuals withconstricted pods in the F, generation?

Inflated pod shape is dominant to constricted pod shape

if the normal spermatogenesis is disrupted, the gametes can have different chromosomes than expected. Which of the following is the most likely cause of one of the four gametes having two X chromosomes and one having neither an X or a Y chromosome

Nondisjunction of the X chromosome during meiosis II

In peas the trait for tall plants is dominant (7) and the trait for short plants is recessi»e k The trait for yellow seed color is dominant (y) and the trait for green seed odor is recessiye «r)-A cross between two plants results in 296 tall yellow plants and 104 tall gieen plants_Wnich of ihe iollowingare most likely to be the genotypes of the parents?

TtYy x TTYy

The diagram above depicts a karyotype of an individual human. Which of theFollowing statements concerning the karyotype in the diagram is true?

The diagram illustrates the results of nondisjunclion during gamete formation

Which of the following best supports the hypothesis that the difference in, leaf color is genetically controlled?

The existence of yellow-leaved seedlings as well as green-Ieaved seedlings on day 14 in dish B

Eye color in a particular strain of fly is influenced by one gene with two alleles : a dominant allele that results in red eyes and a/ecessive allele that results irkseia eyesy A red-eyed fëmare from a t>mnnmMg population is mated with a sepia-eyed male. The F1 offspring are all red-eyed. The F1 flies are allowed to interbreed, producing the following in the F2 generation. Females 40 red eyes 1 3 sepia eyes Males 39 red eyes 1 1 sepia eyes Which of the following best describes the likely mode of inheritance for the eye-color gene?

The eye color gene is likely autosomal because males and females have similar phenotype ratios.

Red-green color-blindness in humans is caused by a recessive allele...How would the extra chromosome affect the male offspring produced by the gamete?

The male offspring would have full-color vision, because of the presence of the extra X chromosome.

Pedigree of Russian blue cats owned by Russian Blue Club...Based on the inheritance pattern shown in Figure 1, which of the following best predicts the nature of the original mutation?

a recessive mutation on a somatic chromosome

Which of the following occurs in all species of living organisms and may lead to an increase in genetic variation?

mutations in the genome

If individual 2 were to marry a woman with no family history of the disease, which of the following would most likely be true of their children?

none of the children would have the disease

In Table I, the ratio Phenotypes in the offspring from the testcross with F1 plants that had purple flowers and inflated pods suggests that the genes for the flower and pod shape are located

on different chromosomes

A blue flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. Thes seeds germinate and grow into flowering plants. Of these plants, 36 produce blue flowers and 1 produce pink flowers. What is the best explanation for the pink-flowered offspring?

pink flower color is trait recessive to blue flower

a scientist studying phenotypic variation in a species of a butterfly observed that genetically identical caterpillars grown in similar cages...Which of the following best explains the cause of the phenotypic variation observed in the butterflies?

there was differential gene expression of wing color and body size in response to the colors of light the caterpillars were exposed to.

A male fruit fly... In the F1 generation, the results are best explained by the fact that

these genes for eye color and wing shape are found on the same chromosome