Biology exam chap 9-11
Which of the following statements are true of cytokinesis in plant cells? Select the two that apply. - After chromosome separation is complete, a network of microfilaments forms near the plane of cell division that will separate the two new cells. - The plasma membrane of the parent cell grows inward, eventually joining with the cell plate. - The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. - Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
-----The cell plate consists of the plasma membrane and cell wall that will eventually separate the two daughter cells. -----Vesicles from the Golgi apparatus move along microtubules, coalesce at the plane of cell division, and form a cell plate.
Which of the following statements are true regarding Down syndrome?
-It can be detected using a karyotype. -It is also called trisomy 21. -It can result from nondisjunction in either meiosis I or meiosis II.
What would happen if the chromosome number were NOT cut in half during the process of meiosis in humans?
-Upon fertilization, the zygote would have a different number of chromosomes from the parents. -Gametes would be diploid instead of haploid. -Upon fertilization, the zygote would be inviable because it would have more than 47 chromosomes.
A cell in prophase I has a diploid number (2n) of 36. At the end of meiosis II, how many sets of chromosomes will each gamete have?
1 set of chromosomes for a total of 18 chromosomes Submit
If a sexually reproducing organism has a diploid number of 36, how many individual chromosomes would any of its gametes have?
18 chromosomes
A cell in G2 of the cell division cycle contains 20 chromatids. How many centromeres are present in this cell?
20
Somatic cells in elephants have 56 chromosomes. How many chromosomes would be carried by the gametes produced by elephants?
28
Beginning with a fertilized egg (zygote), how many cells would be present in an embryo following a series of five cell divisions?
32
What number and types of chromosomes are found in a human somatic cell?
44 autosomes and 2 sex chromosomes
A human bone marrow cell, in prophase of mitosis, contains 46 chromosomes. How many chromatids does it contain?
92
Which of the following statements correctly describes an organism's genome?
A genome is a complete set of all of an organism's genes.
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 statement correctly describes how cellular DNA content and ploidy levels change during meiosis I and meiosis II?
DNA content is halved in both meiosis I and meiosis II. Ploidy level changes from diploid to haploid in meiosis I, and remains haploid in meiosis II.
Which of the following is true of an organism that has a chromosome number of 2n = 16?
Each cell has eight homologous pairs of chromosomes.
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
Which of the following processes happens during meiosis I?
Homologous chromosomes of a pair are separated from each other.
Which of the following statements correctly describes the differences between sexual and asexual reproduction?
In sexual reproduction, offspring vary genetically from their siblings and both parents.
Synapsis occurs during _____.
Prophase I
During _____ a spindle forms in a haploid cell.
Prophase II
Which of the following phases make up the stages of mitosis?
Prophase, prometaphase, metaphase, anaphase, and telophase
Which of the following statements regarding sexual life cycles is correct?
Sexual life cycles can produce both haploid and diploid cells at different stages.
Which of the following occurs during meiosis but not during mitosis?
Synapsis occurs.
What must happen to a chromosome before a cell starts mitosis?
The single DNA molecule in the chromosome must be replicated. Submit
Which statement correctly describes the chromosomes in each daughter cell at the end of meiosis I?
The sister chromatids of each duplicated chromosome are no longer identical. Submit
If crossing over did not occur, which of the following statements about meiosis would be true? Select all that apply.
There would be less genetic variation among gametes.
Which of the following statements is correct regarding human X and Y chromosomes?
They are responsible for the determination of an individual's sex.
Humans produce skin cells by mitosis and gametes by meiosis. Which of the following statements about the nuclei of skin cells is correct?
They contain twice as much DNA as the nuclei of gametes produced by meiosis.
Why is it difficult to observe individual chromosomes with a light microscope during interphase?
They have uncoiled to form long, thin strands.
Why do some species employ both mitosis and meiosis, whereas other species use only mitosis?
They need both if they are reproducing sexually.
Which of the following is true of benign tumors but not malignant tumors?
They remain confined to their original site.
Which of the following statements best describes a karyotype?
a display of all 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 types of cells would be produced by meiosis?
a haploid animal cell
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely __________.
a plant cell in the process of cytokinesis
A human cell containing 22 autosomes and a Y chromosome is __________.
a sperm
Which of the following events characterizes metaphase of mitosis?
alignment of the chromosomes at the equator Submit
Which of the following events might result in a human zygote with 45 chromosomes?
an error in either egg or sperm meiotic anaphase
At which phase of mitosis do the sister chromatids become daughter chromosomes?
anaphase
the chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of the cell as their kinetochore microtubules shorten.
anaphase
Homologous chromosomes migrate to opposite poles during _____.
anaphase I
During _____ sister chromatids separate.
anaphase II
Asexual reproduction __________.
can result in offspring that are genetically identical to the parent
In the cells of some organisms, mitosis occurs WITHOUT cytokinesis. This will result in __________.
cells with more than one nucleus
2. After chromosomes condense, the _______ is the region where the identical DNA molecules are most tightly attached to each other.
centromere
The centrosome(s) are the organizing centers for microtubules involved in separating chromosomes during mitosis.
centrosome(s)
During interphase, most of the nucleus is filled with a complex of DNA and protein in a dispersed form called________
chromatin
Which of these is NOT a carcinogen?
cigarette smoke, fat, UV light, testosterone, all of the above are carcinogens -all of these substances can cause cancer
In most eukaryotes, division of the nucleus is followed by __________, when the rest of the cell divides.
cytokinesis
During telophase, the nonkinetochore microtubules ______
disassemble
Chromatids are separated from each other during which of the following processes?
during both mitosis and meiosis II
_____ is a carcinogen that promotes colon cancer.
fat
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
During _____ the cell grows and replicates both its organelles and its chromosomes.
interphase
In dividing cells, most of the cell's growth occurs during _______
interphase
During mitosis, microtubules attach to chromosomes at the
kinetochore
In some organisms, such as certain fungi and algae, cells undergo the cell cycle repeatedly without subsequently undergoing cytokinesis. What would result from this?
large cells containing many nuclei
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 characteristics are most likely for the two chromosomes of the pair to have in common?
length, centromere position, staining pattern, and traits coded for by their genes
During prophase, the microtubules of the mitotic spindle
lengthen
During anaphase, the non-kinetochore microtubules ________ and move past each other, and the kinetochore microtubules _______
lengthen, shorten
Genetic variation occurs when chromosomes are shuffled in fertilization and what other process?
meiosis
Which of the following elements do all sexual life cycles in eukaryotic organisms have in common?
meiosis and fertilization
the spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the plate.
metaphase
During _____ chromosomes align single file along the equator of a haploid cell.
metaphase II
What will be the result if a eukaryotic cell completes mitosis but does not undergo cytokinesis?
one cell with two nuclei, each identical to the nucleus of the parent cell
discrete chromosomes are now visible; each consists of two aligned, identical sister chromatids. Later the nuclear envelope will fragment.
prometaphase
the chromosomes are condensing and the nucleolus is beginning to disappear. The mitotic spindle is starting to form.
prophase
Which of the following does NOT occur during mitosis?
replication of the DNA
What diagnostic procedures can a karyotype be used for?
screening for defective or abnormal numbers of chromosomes in an individual
1. DNA replication produces two identical DNA molecules, called __________, which separate during mitosis.
sister chromatids
Following DNA replication, each eukaryotic chromosome consists of two identical DNA molecules known as
sister chromatids
In alternation of generations, what is the diploid stage of a plant that follows fertilization called?
sporophyte
daughter nuclei are forming. Cytokinesis has started: The cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell.
telophase
At the end of _____ and cytokinesis, haploid cells contain chromosomes that each consist of two sister chromatids.
telophase I
At the end of _____ and cytokinesis there are four haploid cells.
telophase II
What is crossing over?
the exchange of homologous portions of nonsister chromatids
During _____ both the contents of the nucleus and the cytoplasm are divided.
the mitotic phase
is a cell structure consisting of microtubules, which forms during early mitosis and plays a role in cell division.
the mitotic spindle
Independent assortment of chromosomes during meiosis is a result of
the random and independent way in which each pair of homologous chromosomes lines up at the metaphase plate during meiosis I.
For what purpose(s) might a karyotype be prepared?
to determine whether a fetus is male or female for prenatal screening, to determine if a fetus has the correct number of chromosomes to detect the possible presence of chromosomal abnormalities such as deletions,inversions, or translocations The first three answers are correct.
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
In a typical animal, mitosis produces ____________ while meiosis produces _____________.
two diploid daughter cells ... four haploid daughter cells