Mastering Bio: Cell Cycle, Mitosis and Meiosis
Which of the following is an example of alternation of generations?
A diploid plant (sporophyte) produces, by meiosis, a spore that gives rise to a multicellular, haploid pollen grain (gametophyte).
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 happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other.
For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Homologous chromosomes are aligned at the equator of the spindle.
II
For what purpose(s) might a karyotype be prepared?
The first three answers are correct.
Which of the following is NOT true concerning cancer cells?
When they stop dividing, they do so at random points in the cell cycle; they are not subject to cell cycle controls; and they exhibit density-dependent inhibition when growing in culture.
When a cell is in late anaphase of mitosis, which of the following will we see?
a clear area in the center of the cell
Which of the following best describes a karyotype?
a display of each of the chromosomes of a single cell
What is a cleavage furrow?
a groove in the plasma membrane between daughter nuclei
Which of the following can utilize both mitosis and meiosis in the correct circumstances?
a plantlike protist
In alternation of generations, what is the diploid stage of a plant that follows fertilization called?
sporophyte
Which of the following defines a genome?
the complete set of an organism's genes
Mitosis is commonly found in all of the following except
haploid animal cell.
After telophase I of meiosis, the chromosomal makeup of each daughter cell is
haploid, and the chromosomes are each composed of two chromatids.
Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?
lack of appropriate cell death
At which stage of mitosis are chromosomes usually photographed in the preparation of a karyotype?
metaphase
Compared to most prokaryotic cells, eukaryotic cells typically have
more DNA molecules and larger genomes.
What is produced if the nucleus of a cell divides by mitosis but the cytoplasm does not undergo cytokinesis?
one cell with two nuclei, each identical to the nucleus of the parent cell
Which of these is a karyotype?
organized images of a cells chromosomes
To visualize and identify meiotic cells at metaphase with a microscope, what would you look for?
pairs of homologous chromosomes all aligned at the cell's center
Asexual reproduction _____.
produces offspring genetically identical to the parent
At which phase are centrioles beginning to move apart in animal cells?
prophase
When we see chiasmata under a microscope, that lets us know which of the following has occurred?
prophase I
Movement of the chromosomes during anaphase would be most affected by a drug that prevents
shortening of microtubules.
The beginning of anaphase is indicated by which of the following?
Cohesin is cleaved enzymatically.
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
32
What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes
If there are 20 chromatids in a cell, how many centromeres are there?
10
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?
92
Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. This phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. A growth inhibiting signal is sent to both cells, preventing them from dividing. Certain external physical factors can affect this inhibition mechanism. Select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.
As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.
In a dividing cell, the mitotic (M) phase alternates with interphase (I), a growth period. The figure shows the cell cycle. Interphase is the biggest part, it consists of G1 phase, S phase, and G2 phase. Mitotic phase consists of mitosis and cytokinesis. In the end of mitotic phase the cell divides into two daughter cells. 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.
Which is the first checkpoint in the cell cycle where a cell will be caused to exit the cycle if this point is not passed?
G1
Which of the following correctly matches a phase of the cell cycle with its description?
G1: follows cell division
Identify all possible products of meiosis in plant and animal life cycles.
Gametes (sperm and eggs) Spores
The cell cycle control systems of cancer cells differ from those of normal cells. Select the best explanation for this fact.
Genetic changes alter the function of the cancer cell's protein products.
In eukaryotes, genetic information is passed to the next generation by processes that include mitosis or meiosis. Which of the explanations identifies the correct process and supports the claim that heritable information is passed from one generation to another?
In asexual reproduction, a single individual is the sole parent and passes copies of its genes to its offspring without the fusion of gametes.
The cyclin component of MPF is destroyed toward the end of which phase?
M
Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?
MPF
Which of the following is released by platelets in the vicinity of an injury?
PDFG
Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms. Which statement best represents the connection between reproduction and evolution?
Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms.
Which of the following occurs during meiosis but not during mitosis?
Synapsis occurs
Image of a cell with six duplicated chromosomes. Three are red (maternal) and three are blue (paternal). What is the best evidence telling you whether this cell is diploid or haploid?
The cell is diploid because it contains two sets of chromosomes.
During meiosis, homologous chromatids exchange genetic material by a process called crossing over. This process increases genetic variation in the gametes that are produced. The figure shows the type of meiotic processes and fertilization for animals. Gametes fuse together in the process called fertilization and form a diploid zygote, which develops into diploid multicellular organism through a series of mitotic divisions. Then meiosis occurs in organism's cells and produces haploid gametes and the cycle repeats. The figure shows the type of meiotic processes and fertilization for plants and some algae. Haploid gametes fuse and form a diploid zygote, which develops into diploid multicellular organism or sporophyte through a process called fertilization. The cells of sporophyte undergo meiosis and form haploid spores. Spores grow into haploid multicellular organism called gametophyte, which produce haploid gametes through mitosis and the cycle repeats. The figure shows the type of meiotic processes and fertilization for most fungi and some protists. Haploid gametes fuse and form a diploid zygote through a process called fertilization. Then zygote undergoes meiosis and forms haploid cells, which grow into haploid unicellular or multicellular organism. This organism produces haploid gametes and the cycle repeats. Which of the following explanations of other meiotic processes and fertilization would also increase variation within a population?
The random fertilization of egg cells by sperm increases variation within the population by producing new combinations of chromosomes within the zygote.
Independent assortment of chromosomes occurs.
The statement is true for meiosis I only.
Chromatids are separated from each other.
The statement is true for mitosis and meiosis II.
All cell cycle checkpoints are similar in which way?
They give the go-ahead signal to progress to the next checkpoint.
Why is it difficult to observe individual chromosomes with a light microscope during interphase?
They have uncoiled to form long, thin strands.
Which of the following is true of benign tumors, but not malignant tumors?
They remain confined to their original site
Image of a cell with six duplicated chromosomes. Three are red (maternal) and three are blue (paternal). Look at the cell in the figure. Based on this figure, which of the following statements is true? Image of a cell with six duplicated chromosomes. Three are red (maternal) and three are blue (paternal). Look at the cell in the figure. Based on this figure, which of the following statements is true?
This cell is a dipoliod
Which of the following might result in a human zygote with 45 chromosomes?
an error in either egg or sperm meiotic anaphase
During which phase of mitosis do the chromatids become chromosomes?
anaphase
In eukaryotic cells, chromosomes are composed of DNA
and proteins.
which of the following best describes the frequency of crossing over in mammals?
at least 1-2 per chromosome pair
Which of these is a way that the sexual life cycle increases genetic variation in a species?
by allowing crossing over
Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in concentration during the cell cycle, are called
cyclins
What is crossing over?
the exchange of homologous portions of nonsister chromatids
Humans produce skin cells by mitosis and gametes by meiosis. The nuclei of skin cells produced by mitosis will have
twice as much DNA as the nuclei of gametes produced by meiosis.
Mitosis results in the formation of how many cells; meiosis results in the formation of how many cells?
two diploid cells ... four haploid cells