next biology test

Human gametes are produced by _____.

meosis

Normal human gametes carry _____ chromosomes.

23

In human gamete production there is an average of _____ crossover events per chromosome pair.

2-3

In a diploid cell with 5 chromosome pairs (2n = 10), how many sister chromatids will be found in a nucleus at prophase of mitosis?

20

What number and types of chromosomes are found in a human somatic cell?

44 autosomes and 2 sex chromosomes

What number and types of chromosomes are found in a somatic cell in an animal with a diploid number of 48?

48 chromosomes (24 from each parent, including one sex chromosome from each)

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?

63 chromosomes in 3 sets of 21

Two sister chromatids are joined at the centromere prior to meiosis. Which statement is correct?

Barring mutation, the two sister chromatids must be identical.

Which of the following processes occurs when homologous chromosomes cross over in meiosis I?

Corresponding segments of non-sister chromatids are exchanged.

Select the part of the cell cycle where the cell actually produces two new identical cells.

Cytokinesis when the cytoplasm divides forming two new cells.

Which statement provides the best description of the interphase portion of the cell cycle?

During interphase, a cell is metabolically active.

If a eukaryotic cell is in the G1 phase of the cell cycle, which statement about the cell's chromosomes must be correct?

Each chromosome is made of a complex of DNA and associated proteins.

Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in

G1

How are sister chromatids and homologous chromosomes different from each other?

Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.

Which of the following events happens at the conclusion of meiosis I?

Homologous chromosomes of a pair are separated from each other.

If a cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II, which of the following is an appropriate description of its genetic contents?

It has half the amount of DNA as the cell that began meiosis.

Which of the following statements is correct regarding the human X chromosomes?

It is present in every somatic cell of males and females.

Which of the following statements describes a major difference between meiosis II and mitosis in a diploid animal?

Meiosis II occurs in a haploid cell, while mitosis occurs in diploid cells

How does natural selection apply to sexual reproduction as opposed to asexual reproduction?

Sexual reproduction results in many new gene combinations, some of which will lead to differential reproduction.

Which of the following characteristics do homologous chromosomes exhibit?

They carry information for the same characters.

Normal hemoglobin is a tetramer, consisting of two molecules of β-globin and two molecules of α-globin; normal hemoglobin molecules do not associate with each other. In sickle-cell disease, the change in a single amino acid results in mutant hemoglobin tetramers, which associate with each other and assemble into large fibers. Based on this information alone, what can we conclude about the changes in the structure of sickle cell hemoglobin as compared to normal hemoglobin?

altered primary and quaternary structure

During which phase of mitosis do the chromatids become chromosomes?

anaphase

Centromeres of sister chromatids disjoin and chromatids separate.

anaphase 2

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?

by fertilization

The bulldog ant has a diploid number of two chromosomes. Therefore, following meiosis, each daughter cell will have a single chromosome. In addition to mutations, how might genetic diversity be generated in this species?

crossing over and random fertilization

Heritable variation is required for which of the following?

evolution

Which processes lead to most genetic variation in sexually reproducing organisms?

independent assortment of chromosomes in meiosis crossing over random fertilization

Homologous chromosomes are aligned at the equator of the spindle.

metaphase

Homologous pairs of chromosomes are lined up independently of other such pairs during _____.

metaphase I

During which of the following processes do homologous pairs of chromosomes align adjacent to one another at the metaphase plate of a cell?

metaphase I of meiosis

Crossing over, resulting in an increase in genetic variation, occurs between _____.

nonsister chromatids of homologous chromosomes

The information contained in DNA is used to make which of the following product(s)?

proteins, mRNA, and tRNA

Movement of the chromosomes during anaphase would be most affected by a drug that prevents which of the following events in mitosis and cell division?

shortening of microtubules

Which of the following occurs during meiosis but not during mitosis?

synapsis occurs

What is crossing over?

the exchange of homologous portions of nonsister chromatids

Somatic cells of roundworms have four individual chromosomes per cell. How many chromosomes would you expect to find in an ovum from a roundworm?

two

In diploid cells: mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?

two diploid cells ... four haploid cells