Ch. 8 HW Questions
A human bone marrow cell in the prophase stage of mitosis contains 46 chromosomes. Therefore, there are a total of _____ sister chromatids in this cell.
92
Which of the following checkpoints DOES NOT occur late in G1?
A check that chromosome replication has been successfully completed.
_______ reproduction is a means of creating new individuals solely by ______, the form of cell division that creates genetically identical daughter cells.
Asexual; mitosis.
The first step of bacterial replication is...
DNA replication.
Why are individuals with an extra chromosome 21, which causes Down Syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16?
Extra copies of the other somatic chromosomes are probably fatal.
Eukayotic cells spend most of their cell cycle in which phase?
Interphase
Within one chromosome, what is the relationship between the sequence of bases in DNA of one sister chromatid compared to the other?
The sequences are identical.
During ____ the cell grows and replicates both its organelles and its chromosomes.
interphase
When we say that an organism is haploid, we mean that...
its cells each have one set of chromosomes.
Sister chromatids are...
joined together at a centromere.
In some organisms such as certain fungi and algae, cells undergo mitosis repeatedly without subsequently undergoing cytokinesis. What would be the consequence of this?
large cells containing many nuclei
Gametes are produced by....
meiosis.
Variation occurs when chromosomes are shuffled in _____.
meiosis.
During which phase of mitosis do the chromosomes line up on a plane equidistant from the two spindle poles?
metaphase
After fertilization, the resulting zygote begins to divide by...`
mitosis.
Down syndrome can be the result of...
nondisjunction of chromosome 21 during meiosis.
Crossing over occurs during...
prophase I.
What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?
- The amount of DNA present - Whether the DNA is housed in a nucleus or not. - Whether the DNA is linear or circular.
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
16
Normal human gametes carry ____ chromosomes.
23
A certain species of animal has six pairs of chromosomes. How many DNA molecules are present in the nuclei of these animals during G2 phase?
24
In meiosis II, ____
sister chromatids are separated.
DNA replication occurs in...
the S phase of interphase.
During _____ both the contents of the nucleus and the cytoplasm are divided.
the mitotic phase
During mitosis, the chromosomes move because...
they attach to a dynamic, precisely regulated mitotic spindle.
Mitosis and cytokinesis result in the formation of _____; meiosis and cytokinesis result in the formation of ______.
two diploid cells; four haploid cells.
At the end of telophase I of meiosis, as cytokineses occurs, there are...
two haploid cells.
True or false: Mitosis takes place during M phase of the cell cycle, which is no longer than interphase.
False.
Immune system cells enter a resting phase after undergoing mitosis. When activated- for example, by an infection- they can reenter the sequence of events in the cell cycle that leads to cell division. What would be the correct cell cycle sequence of events for these reactivated cells?
G1, S, G2, M
During binary fission, each copy of the duplicating chromosomes moves to opposite ends of the cell. What does this achieve?
It ensures that each daughter cell receives one copy of the chromosome.
Which of the following statements regarding mitosis and meiosis is false?
Mitosis produces daughter cells with half the number of chromosomes as the parent cell.
Which of the following statements regarding sexual and asexual reproduction is true?
Sexual reproduction is more likely to increase genetic variation than is asexual reproduction.
In many organisms, including humans, chromosomes are found in homologous pairs. Homologous chromosomes....
are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes.
Bacteria divide by...
binary fission.
The chromosomal region where the nonsister chromatids are crossing over is called a(n)....
chiasma.
Which of the following types of organisms commonly demonstrates polyploidy?
flowering plants
Which of the following is a feature of plant cell division that distinguishes it from animal cell division?
formation of a cell plate
During asexual reproduction, yeast cells can produce _____
genetically identical offspring.
