CH 9 Mastering Bio

In the laboratory fruit fly, n is 4. How man different chromosome set can be produced by one fly, excluding crossing over?

2^4 variations; among each chromosome pair, a choice can be made. This means 2 to the power of n unique combinations exist.

A cell preparing to undergo meiosis duplicates its chromosomes during

Chromosomes are duplicated during interphase.

At the end of the mitotic (M) phase, the cytoplasm divides in a process called _____________.

Cytokinesis is the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis.

At what point in the cell cycle does a cell decide to undergo cell division?

G1; the decision in G1 to divide is what causes the cell to progress to S phase.

How do the genes in DNA control cell function?

Genes carry the instructions for making proteins; genes control cells by controlling protein production.

How are homologous chromosomes defined?

Homologous chromosomes have identical genes, but may have different varieties of that gene (different alleles)

During prophase I of meiosis

Homologous chromosomes stick together in pairs during prophase I.

What word is used to describe the exact position of a gene on a chromosome?

Locus

Which of the following is a correct description of meiosis?

Meiosis is one round of DNA replication followed by two rounds of cell division to reach the haploid number.

Meiosis starts with a single diploid cell and produces

Meiosis produces four haploid cells.

The chromosomes line up in the center of the cell during which phase of mitosis?

Metaphase occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell.

The correct order of events during meiosis is

Prophase I, Metaphase I, Anaphase I,Telophase I, Cytokinesis, Meiosis II.

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Prophases it the first phase of mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up.

During meiosis, segments of nonsister chromatids can trade places. The recombination of maternal and paternal genetic material is a key feature of meiosis. During what phase of meiosis does recombination occur?

Segments of nonsister chromatids trade places during Prophase I, resulting in recombination.

What is the most important reason for sexual reproduction?

Sexual reproduction creates genetically unique individuals. The products of asexual reproduction are clones of the parent cells. Genetic uniqueness allows a species to adapt better to its environment.

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

Sister chromatids separate and start their migration toward opposite poles during anaphase.

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?

Telophase is the final phase of mitosis, when the chromosomes have arrived at the poles and the nuclear envelopes of the two new cells form.

Which cellular structure contributes to the biggest difference between mitosis in plants and mitosis in animals?

The cell wall of plants is rigid, preventing the cell from being pinched in half by a microfilament belt.

What must happen before a cell can begin mitosis?

The chromosomes must be duplicated, which occurs during interphase.

Which of the following events occurs during prophase?

The spindle microtubules must form before DNA can be sorted and divided.