Question 1

What process produces genetic diversity through random distribution of chromosomes?

Accepted Answer

The answer of What process produces genetic diversity through random...

Question 2

What is an autosome?

Accepted Answer

An autosome is one of the non-sex chromosomes. This means that it is not directly involved in determining an individual's biological sex. Humans have 22 pairs of autosomes plus one pair of sex chromosomes (XX in females, XY in males).

Question 3

A gamete from a human male contains:

Accepted Answer

The answer of A gamete from a human male contains:
...

Question 4

In a human female, what happens to the collection of oocytes in the ovaries once puberty begins?

Accepted Answer

After puberty, one oocyte per month matures and completes meiosis I, resulting in one haploid secondary oocyte and one polar body. The secondary oocyte is then released during ovulation and waits for fertilization to complete meiosis II. If fertilization occurs, the secondary oocyte completes meiosis II to become a mature ovum. If fertilization does not occur, the ovum and the polar body degenerate. The remaining oocytes in the ovaries continue to undergo a process known as atresia, where they degenerate over time and are reabsorbed by the body.

Question 5

What factors produce genetic diversity in bacteria?

Accepted Answer

Genetic diversity in bacteria is primarily produced by mutation (changes in DNA sequence) and gene transfer (horizontal gene transfer, such as conjugation, transformation, or transduction). While bacteria do undergo cell division, this is not considered mitosis as it does not involve the formation of a spindle apparatus or separation of chromosomes. Similarly, while bacteria can exchange genetic material through horizontal gene transfer mechanisms, they do not undergo meiosis and therefore do not have independent assortment of chromosomes. While bacteria can undergo homologous recombination, this is not considered crossing over as there are no homologous pairs of chromosomes to exchange genetic material between.

Question 6

In gamete formation, the starting cells in females are the ________, and the starting cells in males are ________.

Accepted Answer

The answer of In gamete formation, the starting cells in...

Question 7

In the process of egg production, one cell produced during meiosis will become the egg, and the other three will become:

Accepted Answer

During meiosis, one cell becomes the mature egg, while the other three cells become non-functional polar bodies that eventually disintegrate. Therefore, the best choice is D: polar bodies.

Question 8

In birds, the female carries an unmatched pair of chromosomes (denoted WZ), corresponding roughly to the XY chromosomes in mammalian males, and male birds carry a matched set of chromosomes (denoted WW), corresponding to the pair of XX chromosomes in mammalian females. Therefore, in birds the ________ chromosome determines the sex of the offspring, and it is gametes from the ________ parent that determine sex.

Accepted Answer

In birds, the female carries a pair of sex chromosomes denoted as WZ, where W is the larger chromosome and Z is the smaller one. The male carries a matched pair of sex chromosomes, denoted as WW. Therefore, it is the female bird's gamete that determines the sex of the offspring. If the egg carries a W chromosome, the offspring will be female (ZW), and if the egg carries a Z chromosome, the offspring will be male (ZZ). Thus, option B is the correct answer as the Z chromosome determines sex, and gametes from the female parent determine the offspring's sex.

Question 9

If a 2n cell has three chromosome pairs, how many different combinations of chromosomes are possible in gametes after meiosis?

Accepted Answer

The number of different combinations of chromosomes possible in gametes after meiosis is given by 2^n, where n is the number of chromosome pairs. Here, n=3, so the number of combinations is 2^3 = 8.

Question 10

In metaphase I ________ are aligned along the metaphase plate, and in metaphase II ________ are aligned along the metaphase plate.

Accepted Answer

In metaphase I of meiosis, homologous chromosomes (not sister chromatids) pair up and align along the metaphase plate. In metaphase II, pairs of sister chromatids (not homologous chromosomes or tetrads) align along the metaphase plate, as the sister chromatids separate from each other. Therefore, D is the correct choice as it correctly identifies the structures that align in each metaphase.

Question 11

What is the result of independent assortment during meiosis?

Accepted Answer

Independent assortment during meiosis results in the random alignment of homologous pairs of chromosomes during metaphase I, leading to the random distribution of maternal and paternal chromosomes into daughter cells during anaphase I. This means that the resulting gametes each have a unique combination of maternal and paternal chromosomes, increasing genetic diversity.

Question 12

If a cell has a haploid number of 5, during mitosis there will be ________ chromosomes at metaphase, ________ chromosomes at anaphase, and ________ chromosomes per daughter cell at telophase.

Accepted Answer

The answer of If a cell has a haploid number...

Question 13

In a human cell that is haploid, how many chromosomes are there? How many are autosomes, and how many are sex chromosomes?

Accepted Answer

A haploid human cell has 23 chromosomes. Of these, 22 are autosomes and 1 is a sex chromosome. Therefore, choice C is the correct answer.

Question 14

A human egg contains:

Accepted Answer

Human eggs (ova) contain 22 autosomes and one X chromosome, as they are haploid cells resulting from meiosis, carrying half the number of chromosomes of somatic cells.

Question 15

Which of the following processes contributes least to genetic diversity?

Accepted Answer

Duplication of DNA does not create new genetic information, it simply creates additional copies of existing information. The other processes listed (crossing over, combining of gametes from two different individuals, and independent assortment of chromosomes at the metaphase plate) all involve the shuffling or recombination of genetic information, which can lead to new combinations of alleles and increased genetic diversity.

Question 16

What would the consequence be if spermatogonia were not stem cells?

Accepted Answer

Spermatogonia are the stem cells that continuously produce sperm throughout a male's life. If spermatogonia were not stem cells, there would only be a limited quantity of sperm that could be produced and once that supply was exhausted, no more could be produced, ultimately leading to infertility.

Question 17

Imagine you start a population of 1 million bacteria from a single bacterial cell. Now imagine that a population this large is started from a male and female housefly. How would these two populations differ?

Accepted Answer

Bacterial populations, especially those started from a single cell, tend to be genetically very similar due to asexual reproduction (binary fission), whereas houseflies reproduce sexually, leading to greater genetic diversity among individuals.

Question 18

What is the fate of sperm that are never released?

Accepted Answer

Sperm that are not released are eventually broken down and absorbed by the body. This process involves the immune system, which helps to clear out cells that are no longer needed or viable, including unused sperm.

Question 19

If a diploid cell has 12 chromosome pairs, how many different combinations of chromosomes are possible in gametes after meiosis?

Accepted Answer

During meiosis, each chromosome pair can independently assort into gametes, leading to 2 possible combinations per pair. With 12 pairs, the total number of combinations is 2^12.

Question 20

What is the result of recombination (crossing over) during meiosis?

Accepted Answer

Recombination (crossing over) during meiosis results in the creation of chromosomes that are a new combination of paternal and maternal material. This creates genetic diversity and variation within populations.

Quiz 10: Preparing for Sexual Reproduction: Meiosis