Question 1

A particular organism has 46 chromosomes in its karyotype. Which of the following statements is correct regarding this organism?

Accepted Answer

The presence of 46 chromosomes in the karyotype indicates that the organism is diploid and produces gametes with 23 chromosomes through meiosis. This is a characteristic of sexually reproducing organisms, which includes both animals and plants. The information given does not provide any indication of whether the organism is human or not.

Question 2

-Which of the life cycles is typical for plants and some algae?

Accepted Answer

C

Question 3

Asexual reproduction occurs during which of the following processes?

Accepted Answer

Asexual reproduction occurs through mitosis, where a single parent creates genetically identical offspring. Meiosis and fertilisation involve the combination of genetic material from two parents, leading to genetic diversity. The exchange of chromosomes between organisms of different species is not a process of reproduction at all.

Question 4

Which of the following characteristics do homologous chromosomes exhibit?

Accepted Answer

Homologous chromosomes carry the same genes in the same locations, although they may carry different alleles (versions) of those genes. This allows for the exchange of genetic material during meiosis, which can lead to genetic diversity in offspring.

Question 5

In a life cycle such as that shown in part III of the figure above, if the zygote's chromosome number is ten, which of the following statements will be true?

Accepted Answer

The answer of In a life cycle such as that...

Question 6

Which of the following statements is true of a species that has a chromosome number of 2n = 16?

Accepted Answer

A species with a chromosome number of 2n=16 is diploid, with two sets (n=8) of homologous chromosomes. Therefore, each diploid cell has eight homologous pairs of chromosomes. Option A is incorrect because it incorrectly states that the species has 32 chromosomes per cell, which would be the case if the species was tetraploid (4n=32). Option B is incorrect as it states that the species has 16 sets of chromosomes per cell, which is not correct since the diploid number is 2n=16, not n=16. Option D is incorrect since gametes will have half the diploid number of chromosomes, i.e. n=8.

Question 7

Which of the following statements is correct in comparing sexual and asexual reproduction?

Accepted Answer

In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring, whereas in asexual reproduction, offspring are produced from a single individual without the involvement of gametes or fusion of nuclei. Asexual reproduction can occur in both plants and animals, while sexual reproduction is characteristic of most animals and many plants. Asexual reproduction can produce either haploid or diploid offspring, depending on the mode of reproduction, while sexual reproduction always produces diploid offspring.

Question 8

Which of the following processes might produce a human zygote with 45 chromosomes?

Accepted Answer

An error in meiotic anaphase during either egg or sperm formation could lead to a gamete with an extra chromosome (producing 24 chromosomes instead of the usual 23). When that gamete combines with a normal 23-chromosome gamete during fertilization, the resulting zygote would have 45 chromosomes instead of the usual 46.

Question 9

Which of the following statements describes an example of alternation of generations?

Accepted Answer

Alternation of generations refers to a life cycle in which there is a alternation between haploid (n) and diploid (2n) stages. In this case, the sporophyte (diploid) produces spores by meiosis, which develop into haploid pollen grains (gametophyte). The pollen grains produce gametes, which then go on to fertilize each other and produce a new sporophyte generation.

Question 10

Eukaryotic sexual life cycles show tremendous variation. Which of the following characteristics do all sexual life cycles have in common?
I. Alternation of generations
II. Meiosis
III. Fertilisation
IV. Gametes
V. Spores

Accepted Answer

All sexual life cycles involve meiosis, the production of gametes, and fertilization. Alternation of generations and spores are not features of all eukaryotic sexual life cycles. Choice B includes these three common features without including the less common characteristics.

Question 11

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?

Accepted Answer

The answer of In a human karyotype, chromosomes are arranged...

Question 12

A triploid cell contains three sets of homologous chromosomes. If a cell of a diploid species that normally has 42 chromosomes per cell is triploid, this cell would be expected to have which of the following sets of chromosomes?

Accepted Answer

A diploid cell of the species normally contains 42 chromosomes. A triploid cell would have three sets of homologous chromosomes. Therefore, the total number of chromosomes in a triploid cell would be 3 x 42 = 126. This set of chromosomes would be divided into 21 sets of three chromosomes. Therefore, the correct answer is 63 chromosomes in 21 sets of 3 (choice B).

Question 13

-Which of the life cycles is typical for most fungi and some protists?

Accepted Answer

The answer of 
-Which of the life cycles is typical...

Question 14

At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?

Accepted Answer

Chromosomes are most easily photographed in metaphase because they are fully condensed and aligned in the middle of the cell.

Question 15

Which of the following processes occurs in a plant's sexual life cycle?

Accepted Answer

The answer of Which of the following processes occurs in...

Question 16

Many organisms spend most of their life cycle in the diploid state. If meiosis produces haploid cells, how is the diploid number restored for these types of organisms?

Accepted Answer

Organisms that spend most of their life cycle in the diploid state restore the diploid number through fertilization, where haploid gametes from two individuals combine to form a diploid zygote.

Question 17

Quaking aspen trees can send out underground stems for asexual reproduction. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?

Accepted Answer

The haploid gametes have 19 chromosomes, which means that the diploid cells have twice that number, or 38 chromosomes. The underground stems are likely to be diploid, since they are involved in asexual reproduction, which usually relies on somatic cells.

Question 18

If a horticulturist breeding gardenias succeeds in having a single plant with a particularly desirable set of traits, which of the following would be the most probable and efficient route to establishing a line of such plants?

Accepted Answer

Cloning the plant would ensure that the exact same set of desirable traits is passed down to the next generation. This method is efficient and reliable since it eliminates the possibility of genetic variation that could occur through sexual reproduction or selection of offspring from backcrossing.

Question 19

Which of the following statements defines a genome?

Accepted Answer

A genome is the complete set of an organism's genes and other DNA sequences, including non-coding regions. It consists of both coding DNA sequences that transcribe into functional mRNA and non-coding DNA sequences with regulatory functions. A genome encodes all the information necessary for an organism's development, growth, and function. Options A and B are incorrect because they only refer to the set of polypeptides, while option C refers to an ordered display of an individual's chromosomes.

Question 20

-Which of the life cycles is typical for animals?

Accepted Answer

Life cycle I is typical for animals, where the organism goes through stages of fertilization, embryonic development, birth/hatching, growth and development, reproduction and death. Life cycle II is typical for fungi, and life cycle III is typical for plants.

Quiz 13: Meiosis and Sexual Life Cycles