bio chapter 5

which step does not occur in meiosis I

which step does not occur in meiosis I

sister chromatids are pulled apart by meiotic spindles

which statement is true about meiosis II?

meiotic spindles attach to kinetochores and cause sister chromatids to separate

Which process does not lead to new genetic combinations during meiosis?

fertilization

If the diploid number of chromosomes in a dog is 78, how many chromosomes are present in a single cell during prophase I, prophase II, telophase II, and in a zygote, respectively?

78, 39, 39, 78

Which of the following processes is not unique to meiosis compared to mitosis?

Spindles attaching to opposite sides of a centromere

_____________ is the set of genes that an organism carries, while _______________ is the set of traits that the organism expresses as a result of the genes it carries (and environmental conditions)

genotype ; phenotype

Categorize each description/event as fitting for "sexual"

• meiosis

  two parents

  offspring are genetically unique compared to parents

  is more costly in terms of energy and resources, but produces genetic variation

Categorize each description/event as fitting for "asexual"

one parent

offspring are genetically identical to parents

binary fission

mitosis

Synapsis occurs....

in prophase I when homologous chromosomes pair up

In a Karyotype, the chromosomes are displayed in an organized manner. Other than the sex chromosomes, the rest of them are considered...

autosomes

The most important distinction between Meiosis I and Meiosis II is that....

during Meiosis I, the homologous chromosomes separate. But during Meiosis II, sister chromatids separate.

Consider the end of Meiosis I. Check all the conditions that apply.

• there are two daughter cells at this point (before beginning Meiosis II)

• each chromosome is a replicated chromosome (it has a centromere with 2 chromatids), but the chromatids may not be identical to each other

• the cells produced are haploid

If a cell begins Meiosis with 8 chromosomes, what is the best description of each daughter cell at the end of Meiosis?

4 individual chromosomes

Which description is true of the resulting gametes formed in males vs. females?

in females, there are 4 haploid cells. But one remains and the other 3 degrade into polar bodies

In regard to genotypes and phenotypes, which statement is true?

Genotypes indicate the alleles that an organism carries while phenotypes are the traits that organisms express.

Which statement about the law of segregation is true?

It helps explain how genetic variation is maintained over generations, which can be observed when traits are able to "skip" generations (the trait never "disappeared," it was only "masked").

What is a likely outcome of self-fertilizing an F1 generation of heterozygotes that was produced by crossing purebred parents that are homozygous for a different allele?

The F2 generation will be comprised of 3/4 dominant phenotypes and 1/4 recessive phenotypes.

A cross begins with purebred parents (AABB x aabb) and then the F1 generation is allowed to self-fertilize. Which statement is false?

The F1 generation will have a phenotypic ratio of 9:3:3:1.

Which statement is true about inferring inheritance patterns from pedigrees?

Incomplete penetrance can complicate the interpretation of inheritance

A Punnett square on a dihybrid cross that involves epistasis will likely show

a phenotypic ratio that differs from 9:3:3:1

If researchers crossed one breed of chicken with a CC ii genotype with another chicken having a cc II genotype, what will be the phenotypes of the offspring? Use Figure 28.1 on page 391 (included here)

All offspring will have white feathers.

Which statement is true about X-linked genes?

Males express the recessive trait when they carry one recessive allele

Which statement is true about Y-linked genes?

In mammals, there are many fewer Y-linked genes than X-linked genes.

Which statement is true regarding the inheritance of mitochondrial genes in mammals?

They are maternally inherited.

a pattern of inheritance in which the heterozygote is an intermediate phenotype of the dominant and recessive phenotype is known as which pattern of inheritance? (For example, a blue flower crosses with a white flower to make offspring that are light blue)

incomplete dominance

a pattern of inheritance in which one gene affects the expression of another gene is known as what pattern of inheritance? For example, this is observed in labrador dogs since they are typically brown or black, but another gene can override them and cause them to be yellow, regardless of whether the gene for fur color is black or brown.

epistasis

a pattern of inheritance in which the heterozygote expresses aspects of both the dominant phenotype and the recessive phenotype is known as which pattern of inheritance? (For example, a white chicken crosses with a black chicken and produces an erminette/speckled chicken)

codominance

In a field of cotton plants where the farmer has planted a single genotype, you see differences in plant height. Which statement does this evidence support?

The differences in height are due to differences in environment.

The arctic fox grows a brown coat in the summer and a white coat in the winter. This is an example of

phenotypic plasticity

Why do phenotypic trade-offs favor the evolution of plastic phenotypes?

A phenotype that performs well in one environ-ment performs poorly in other environments.

Which statement about human diseases is not true?

Most diseases are not affected by the environment.

Why are twin studies useful in understanding human diseases?

Differences in disease susceptibility in identical twins are only due to environmental differences.

Tay-Sachs disease

results from a recessive single-gene mutation.

Which statement is true about single-gene mutations?

They occur in all organisms.

Which is an accurate description of the effects of extra or missing chromosomes?

They are often lethal in animals.

Which statement is true about nondisjunction?

It can happen during meiosis and mitosis, but there is potential that its effects are more significant if they occur in meiosis (if a gamete resulting from nondisjunction is involved in fertilization)