Chapter 13

The karyotype of one species of primate has 48 chromosomes. In a particular female, cell division goes awry and she produces one of her eggs with an extra chromosome (25). The most probable source of this error would be a mistake in which of the following?

either anaphase I or II

An advantage of asexual reproduction is that it _____.

enables the species to rapidly colonize habitats that are favorable to that species

For the male Drosophila shown in Figure 13.1, what are the (1) haploid number, (2) ploidy, and (3) total number of chromosomes? See Section 13.1 (Page) .

(1) 4; (2) 2n; (3) 8 - This individual is diploid (2n) with two versions of each of the four types of chromosome.

In Figure 13.14, every asexual individual or sexually reproducing couple produces 4 offspring over a lifetime, sexually reproducing individuals produce half males and half females, and all offspring survive to breed. How many (1) asexually and (2) sexually produced offspring would be present in generation four? See Section 13.4 (Page)

(1) 64; (2) 16

- There are 16 chromosomes in the model. - The color codes in this model will help to show independent assortment - During metaphase I, there will be four pairs of chromosomes (tetrads) aligned at the metaphase plate. -The chromosomes in the model are replicated. - In this model, the color codes emphasize that two homologous chromosomes contain the same genes. - In this model, the color codes emphasize that two homologous chromosomes contain the same alleles. - Since independent assortment can occur in different ways during meiosis, two people could come up with different color-combinations of chromosomes in their drawings of gametes, and both be correct

-false - false - true -true -true -false -false

If a diploid cell undergoes meiosis and produces two gametes with n + 1 chromosomes and two gametes with n− 1 chromosomes, what type of error occurred?

A nondisjunction error occurred in meiosis I, in which both members of a homologous pair migrated to the same pole of the cell. - When this type of error occurs, half of the gametes receive one too many chromosomes, and the other half receive one too few. When all of the gametes are affected, the error probably occurred in meiosis I.

If a diploid cell undergoes meiosis and produces two gametes that are normal, and one with n − 1 chromosomes, and one with n + 1 chromosomes, what type of error occurred?

A nondisjunction error occurred in meiosis II, in which both sister chromatids of a chromosome migrated to the same pole of the cell. - When this error occurs in meiosis II, only half of the gametes are affected.

What is a nondisjunction?

An error in cell division that causes homologous chromosomes or sister chromatids to move to the same side of the dividing cell - Nondisjunction refers to the failure of pairs of chromosomes or sister chromatids to separate during meiosis or mitosis.

True or false? A haploid organism has one pair of homologous chromosomes.

False -A haploid organism only has one set of chromosomes, so it has no homologous chromosomes

Which statement best describes unreplicated chromosomes in a 2n cell where n=3 and in a 3n=6 cell. See Section 13.1 (Page) .

The 2n and 3n cells will both have 6 chromosomes; however, the 2n cell will have 3 different types of chromosomes and the 3n cell will have 2 different types of chromosomes. - When we write ploidy number the "n" refers to the number of different types of chromosomes in a set and the number that precedes "n" indicates the number of sets present.

What information can not be obtained from an individual's karyotype?

The sequence of bases of a particular gene - Karyotypes only give information about the chromosomes in an individual.

Assume that an organism exists in which crossing over does not occur, but that all other processes associated with meiosis occur normally. Consider how the absence of crossing over would affect the outcome of meiosis. If crossing over did not occur, which of the following statements about meiosis would be true?

There would be less genetic variation among gametes.

What makes sexually reproduced offspring genetically different from their parents?

genetic recombination during meiosis

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.

Which is the smallest unit containing the entire human genome?

human somatic cell

Sister chromatids separate from each other during _____.

mitosis and meiosis II

A particular plant species can reproduce both sexually and asexually. When samples of this plant are grown in an environment where a harmful bacterial pathogen is abundant, the plants that survive are likely to have been produced primarily through what type of reproduction? See Section 13.4 (Page) .

sexual _Sexual reproduction will permit variation among the offspring, and some of the offspring were are likely more resistant to the bacterial pathogen.

Review the checklist of tips for drawing chromosomes during independent assortment. Four of the tips were followed, but one was not. Which one?

start with replicated chromosomes - The chromosomes in the model are not shown replicated. Each chromosome should have two chromatids because replication occurs in interphase prior to meiosis.

Independent assortment of chromosomes is a result of _____.

the random way each pair of homologous chromosomes lines up at the metaphase plate during meiosis I

Somatic cells from an individual with Down syndrome (trisomy 21) have ______ copies of the genes on chromosome 20 and ______ copies of the genes on chromosome 21. See Section 13.3 (Page) .

two; three -These individuals are trisomic only for chromosome 21.

Which of the following gametes could result from the cell shown? (Assume that meiosis proceeds normally.)

small black, med blue. large blue

If a cell has 24 chromosomes, how many chromosomes would each of its four daughter cells have after meiosis?

12 - Meiosis is a reduction division that reduces the number of chromosomes passed on to daughter cells by one-half.

In the snail Pomacea patula catemacensis, n = 13. What is the diploid number for this organism?

26

What is the ploidy of organisms that have two sets of chromosomes?

2n

Which structure is directly correlated with the production of genetic variability in the daughter cells produced during meiosis?

Chiasma - The chiasma is an X-shaped structure formed from the crossing over of homologous chromosomes, which can then exchange segments at the crossover sites.

Which metaphase cell could have produced these gametes?

The replicated homologous chromosomes are lined up in pairs during metaphase I of meiosis, with the three smallest red chromosomes on the same side as the largest blue chromosome.

What kind of cell results when a diploid and a haploid gamete fuse during fertilization?

a triploid cell - A triploid cell has three sets of chromosomes: the two from the diploid gamete and the one from the haploid gamete.

Which of the following might result in a human zygote with 45 chromosomes?

an error in either egg or sperm meiotic anaphase

Homologous chromosomes _____.

carry information for the same traits

Which of the following could be considered an evolutionary advantage of asexual reproduction in plants?

increased success of progeny in a stable environment.

A triploid individual _____.

is unable to undergo normal meiosis

When does the synaptonemal complex disappear?

late prophase of meiosis I

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 -

All individuals of a particular species of whiptail lizards are females. Their reproductive efforts depend on _____.

meiosis followed by a doubling of the chromosomes in egg

What is the most common source of the extra chromosome 21 in an individual with Down syndrome?

nondisjunction in the mother

Of the following chromosomal abnormalities, which type is most likely to be viable in humans?

trisomy - Some trisomies are viable in humans, but they result in developmental abnormalities, such as Down syndrome (trisomy 21). Only humans with trisomies of the small chromosomes (13, 18, or 21) or the sex chromosomes survive past birth.

Which of these statements is correct? - In humans, the twenty-second pair, the sex chromosomes, determines whether the person is female (XY) or male (XX). - Single, haploid (2n) sets of chromosomes in ovum and sperm unite during fertilization, forming a diploid (4n), single-celled zygote. - In humans, each of the 23 maternal autosomes has a homologous paternal chromosome. - At sexual maturity, ovaries and testes produce haploid gametes by meiosis.

At sexual maturity, ovaries and testes produce haploid gametes by meiosis.

Sort each process into the appropriate bin according to whether it contributes to heredity only, genetic variation only, or both

Both - fertilizations - DNA Replication - Crossing Over Metaphase 1 & anaphase 1 - metaphase 2 & anaphase 2

When can nondisjunction occur? Choose the best answer.

In meiosis, when sister chromatids fail to separate In mitosis, when sister chromatids fail to separate In meiosis, when homologous chromosomes fail to separate -All three answers are correct.

A student has drawn a series of metaphase I cells to show the principle of independent assortment. Which cell does not belong in the series?

In this series, red and blue are used to distinguish maternal and paternal chromosomes within each homologous pair. However, in this cell, both homologs within each pair are the same color, which is not helpful in showing independent assortment of the homologs. - https://quizlet.com/506854685/meiosis-classwork-flash-cards/

Which of the following statements about meiosis and mitosis is true?

Meiosis II is similar to mitosis in that sister chromatids of each chromosome separate. -Both meiosis II and mitosis are cell divisions involving the separation of sister chromatids.

What is the composition of a tetrad at the beginning of prophase I?

One pair of homologous chromosomes -One chromosome in a tetrad is paternally inherited, while the other is maternally inherited. Each chromosome consists of two chromatids.

Which of the following cell models is a correct illustration of metaphase I for a 2n = 4 cell?

Replicated chromosomes line up at the metaphase plate in homologous pairs (tetrads).

Which event makes meiosis a reductional division and why? See Section 13.1 (Page)

Separation of homologs in meiosis I, because it produces 2 haploid (n) daughter cells from a single diploid (2n) parent cell - Separation of homologs results in a reduction in chromosome number

Which syndrome is characterized by the XO chromosome abnormality?

Turner syndrome -Turner syndrome is characterized by a chromosome pattern of XO, or one X chromosome and no Y chromosome.

The fastest way for organisms to adapt to a changing environment involves _____.

sexual reproduction