Chapter 11: BIO181

Chapter 11 critical thinking/review questions

Meiosis usually produces ________ daughter cells.

1. two haploid

2. two diploid

3. four haploid

4. four diploid

• four haploid

What structure is most important in forming the tetrads?

1. centromere

2. synaptonemal complex

3. chiasma

4. kinetochore

synaptonemal complex

At which stage of meiosis are sister chromatids separated from each other?

1. prophase I

2. prophase II

3. anaphase I

4. anaphase II

anaphase II

At metaphase I, homologous chromosomes are connected only at what structures?

1. chiasmata

2. recombination nodules

3. microtubules

4. kinetochores

chiasmata

Which of the following is not true in regard to crossover?

1. Spindle microtubules guide the transfer of DNA across the synaptonemal complex.

2. Nonsister chromatids exchange genetic material.

3. Chiasmata are formed.

4. Recombination nodules mark the crossover point.

Spindle microtubules guide the transfer of DNA across the synaptonemal complex

What phase of mitotic interphase is missing from meiotic interkinesis?

1. G₀ phase

2. G₁ phase

3. S phase

4. G₂ phase

S phase

The part of meiosis that is similar to mitosis is ________.

1. meiosis I

2. anaphase I

3. meiosis II

4. interkinesis

meiosis II

If a muscle cell of a typical organism has 32 chromosomes, how many chromosomes will be in a gamete of that same organism?

1. 8

2. 16

3. 32

4. 64

16

Which statement best describes the genetic content of the two daughter cells in prophase II of meiosis?

1. haploid with one copy of each gene

2. haploid with two copies of each gene

3. diploid with two copies of each gene

4. diploid with four copies of each gene

haploid with two copies of each gene

The pea plants used in Mendel’s genetic inheritance studies were diploid, with 14 chromosomes in somatic cells. Assuming no crossing over events occur, how many unique gametes could one pea plant produce?

1. 28

2. 128

3. 196

4. 16,384

128

How do telophase I and telophase II differ during meiosis in animal cells?

1. Cells remain diploid at the end of telophase I, but are haploid at the end of telophase II.

2. Daughter cells form a cell plate to divide during telophase I, but divide by cytokinesis during telophase II.

3. Cells enter interphase after telophase I, but not after telophase II.

4. Chromosomes can remain condensed at the end of telophase I, but decondense after telophase II.

Chromosomes can remain condensed at the end of telophase I, but decondense after telophase II

What is a likely evolutionary advantage of sexual reproduction over asexual reproduction?

1. Sexual reproduction involves fewer steps.

2. There is a lower chance of using up the resources in a given environment.

3. Sexual reproduction results in variation in the offspring.

4. Sexual reproduction is more cost-effective.

Sexual reproduction results in variation in the offspring

Which type of life cycle has both a haploid and diploid multicellular stage?

1. asexual life cycles

2. most animal life cycles

3. most fungal life cycles

4. alternation of generations

alternation of generations

What is the ploidy of the most conspicuous form of most fungi?

1. diploid

2. haploid

3. alternation of generations

4. asexual

haploid

A diploid, multicellular life-cycle stage that gives rise to haploid cells by meiosis is called a ________.

1. sporophyte

2. gametophyte

3. spore

4. gamete

sporophyte

Hydras and jellyfish both live in a freshwater lake that is slowly being acidified by the runoff from a chemical plant built upstream. Which population is predicted to be better able to cope with the changing environment?

1. jellyfish

2. hydra

3. The populations will be equally able to cope.

4. Both populations will die.

jellyfish

Many farmers are worried about the decreasing genetic diversity of plants associated with generations of artificial selection and inbreeding. Why is limiting random sexual reproduction of food crops concerning?

1. Mutations during asexual reproduction decrease plant fitness.

2. Consumers do not trust identical-appearing produce.

3. Larger portions of the plant populations are susceptible to the same diseases.

4. Spores are not viable in an agricultural setting.

Larger portions of the plant populations are susceptible to the same diseases

Describe the process that results in the formation of a tetrad

During prophase I of meiosis, homologous chromosomes pair up in a process called synapsis. Each chromosome has two sister chromatids, so the paired homologous chromosomes form a group of four chromatids called a tetrad

Explain how the random alignment of homologous chromosomes during metaphase I contributes to the variation in gametes produced by meiosis

During metaphase I, homologous chromosome pairs line up randomly at the cell's equator. This independent assortment creates different combinations of maternal and paternal chromosomes in gametes, increasing genetic variation

What is the function of the fused kinetochore found on sister chromatids in prometaphase I?

The fused kinetochores ensure that sister chromatids stay together and attach to spindle fibers from the same pole, allowing homologous chromosomes—not sister chromatids—to separate during anaphase I.

In a comparison of the stages of meiosis to the stages of mitosis, which stages are unique to meiosis and which stages have the same events in both meiosis and mitosis?

Prophase I, metaphase I, anaphase I, and telophase I are unique to meiosis because homologous chromosomes pair, cross over, and separate. Meiosis II closely resembles mitosis because sister chromatids separate during anaphase II.

Why would an individual with a mutation that prevented the formation of recombination nodules be considered less fit than other members of its species?

Without recombination nodules, crossing over cannot occur, reducing genetic variation in offspring. Less genetic diversity makes offspring less adaptable to environmental changes, reducing overall fitness.

Does crossing over occur during prophase II? From an evolutionary perspective, why is this advantageous?

No. Crossing over occurs only during prophase I because homologous chromosomes are paired only then. This is advantageous because one round of crossing over creates sufficient genetic diversity while maintaining accurate chromosome separation during meiosis II.

List and briefly describe the three processes that lead to variation in offspring with the same parents

1. Crossing over – Exchange of DNA between homologous chromosomes during prophase I creates new gene combinations.

2. Independent assortment – Random alignment of homologous chromosomes during metaphase I produces different chromosome combinations in gametes.

3. Random fertilization – Any sperm can fertilize any egg, creating many possible genetic combinations.

Animals and plants both have diploid and haploid cells. How does the animal life cycle differ from the alternation of generations exhibited by plants?

In animals, the diploid stage is multicellular, and the haploid stage consists only of gametes. In plants, both the diploid sporophyte and the haploid gametophyte are multicellular stages.

Explain why sexual reproduction is beneficial to a population but can be detrimental to an individual offspring.

Sexual reproduction increases genetic diversity, helping populations adapt to changing environments. However, an individual offspring may inherit less favorable combinations of genes or lose successful gene combinations found in its parents.

How does the role of meiosis in gamete production differ between organisms with a diploid-dominant life cycle and organisms with an alternation of generations life cycle?

In diploid-dominant organisms (such as animals), meiosis produces gametes directly. In organisms with alternation of generations (such as plants), meiosis produces haploid spores, which grow into gametophytes that produce gametes by mitosis.

How do organisms with haploid-dominant life cycles ensure continued genetic diversification in offspring without using a meiotic process to make gametes?

In haploid-dominant organisms, meiosis produces haploid spores, not gametes. The spores grow into haploid individuals that produce gametes by mitosis. Genetic diversity comes from crossing over and independent assortment during meiosis that formed the spores, along with random fertilization.