Exam 3 quizzes

Which of the following is a true statement about sexual vs. asexual reproduction?

In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring.

Hydrangea plants of the same genotype are planted in a large flower garden. Some of the plants produce blue flowers and others pink flowers. This can be best explained by which of the following?

environmental factors such as soil pH

For what purpose(s) might a karyotype be prepared?

for prenatal screening, to determine if a fetus has the correct number of chromosomes to determine whether a fetus is male or female and to detect the possible presence of chromosomal abnormalities such as deletions, inversions, or translocations

Movement of the chromosomes during anaphase would be most affected by a drug that prevents _____.

shortening of microtubules

Which of the following is an example of polygenic inheritance?

skin pigmentation in humans

In alternation of generations, what is the diploid stage of a plant that follows fertilization called?

sporophyte

If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?

10

What number and types of chromosomes are found in a human somatic cell?

44 autosomes and 2 sex chromosomes human somatic cells contain 22 pairs of autosomes and either two X chromosomes (in females) or an X and a Y chromosome (in males)

Density-dependent inhibition is explained by which of the following?

As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.

Which of the following is found in binary fission but not in mitosis?

Duplicated chromosomes attach to the plasma membrane.

Which of the following correctly matches a phase of the cell cycle with its description?

G1: follows cell division

Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?

G2

The cell cycle control systems of cancer cells differ from those of normal cells. Select the best explanation for this fact.

Genetic changes alter the function of the cancer cell's protein products.

A sexually reproducing animal has two unlinked genes, one for head shape (H) and one for tail length (T). Its genotype is HhTt. Which of the following genotypes is possible in a gamete from this organism?

HT

How are sister chromatids and homologous chromosomes different from each other?

Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.

If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents?

It has half the amount of DNA as the cell that began meiosis.

Folk singer Woody Guthrie died of Huntington's disease, an autosomal dominant disorder. Which statement below must be true?

It is very likely that at least one of Woody Guthrie's parents also have had the allele for Huntington's disease.

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

MPF

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early twentieth century?

Mendelian genes are at specific loci on the chromosome and, in turn, segregate during meiosis.

A white-eyed female Drosophila is crossed with a red-eyed male Drosophila. Which statement below correctly describes the results?

None of the females will have white eyes.

Why did the F1 offspring of Mendel's classic pea cross always look like one of the two parental varieties?

One allele was dominant.

One of two major forms of a human condition called neurofibromatosis (NF 1) is inherited as a dominant gene, although it may range from mildly to very severely expressed. Which of the following is the best explanation for why a young, affected child is the first in her family to be diagnosed?

One of the parents has a mild expression of the gene.

Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human X chromosome. The patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. They rarely live past their twenties. How likely is it for a woman to have this condition?

One-half of the daughters of an affected father and a carrier mother could have this condition.

In his breeding experiments, Mendel first crossed true-breeding plants to produce a second generation, which were then allowed to self-pollinate to generate the offspring. How do we name these three generations?

P ... F1 ... F2 Mendel started with true-breeding P generation plants, and in a typical experiment generated two subsequental generations, called F₁and F₂.

You cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. All of the F1 are pink. What does this say about the parental traits?

Red shows incomplete dominance over white.

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?

The gene involved is on the X chromosome.

Which of the following is true of kinetochores?

They are sites at which microtubules attach to chromosomes.

What is true of all cancers?

They have escaped normal cell cycle controls

Why is it difficult to observe individual chromosomes with a light microscope during interphase?

They have uncoiled to form long, thin strands.

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

Traits are inherited in discrete units and are not the results of "blending."

For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Centromeres of sister chromatids disjoin and chromatids separate.

VII

Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely

a plant cell in the process of cytokinesis.

What is an allele?

an alternative version of a gene

During which phase of mitosis do the chromatids become chromosomes?

anaphase

The individual with genotype AaBbCCDdEE can make many kinds of gametes. Which of the following is the major reason?

different possible assortment of chromosomes into gametes

Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to

disruption of mitotic spindle formation.

How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? They have _____.

half the number of chromosomes and one-fourth the amount of DNA.

After telophase I of meiosis, the chromosomal makeup of each daughter cell is _____.

haploid, and the chromosomes are each composed of two chromatids

Neurons and some other specialized cells divide infrequently because they _____.

have entered into G0

A woman is found to have forty-seven chromosomes, including three X chromosomes. Which of the following describes her expected phenotype?

healthy female of slightly above-average height

Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?

lack of appropriate cell death

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

roan × roan

In a human karyotype, chromosomes are arranged in 23 pairs. If we choose one of these pairs, such as pair 14, which of the following do the two chromosomes of the pair have in common?

length, centromere position, staining pattern, and traits coded for by their genes

Mendel continued some of his experiments into the F2 or F3 generation to _____.

observe whether or not a recessive trait would reappear

Which of the following describes the ability of a single allele to have multiple phenotypic effects?

pleiotropy

Asexual reproduction _____.

produces offspring genetically identical to the parent

At which phase are centrioles beginning to move apart in animal cells?

prophase

What is crossing over?

the exchange of homologous portions of nonsister chromatids

Which of the following is the best statement of the use of the addition rule of probability?

the probability that either one of two independent events will occur

Sex determination in mammals is due to the SRY gene. Which of the following could allow a person with an XX karyotype to develop a male phenotype?

translocation of SRY to a X chromosome

Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?

two diploid cells ... four haploid cells

What name is given to the most common phenotype in a natural population?

wild type