Mastering Bio Chapter 8
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
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.
16
Asexual and sexual reproduction differ in that sexual reproduction can produce _________
Great variation among the offspring
A cleavage furrow forms in an animal cell during _____.
cytokinesis
A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes. 1) 16 2) 8 3) 64 4) 30 5) 32
16
Normal human gametes carry _____ chromosomes. 1) 23 pairs of 2) 5 3) 23 4) 46 pairs of 5) 46
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. Each chromosome (12) is replicated, there are 24 DNA molecules in the nucleus during G2 phase.
In humans, the haploid number of chromosomes is 23. Independent assortment has the possibility of producing ______ different types of gametes.
2^23
On average, what percentage of infants born to 45-year-old mothers have Down syndrome?
3%
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
Two types of cell division Part complete Drag the labels onto the grid to indicate the phases of mitosis and meiosis. Use only pink labels for pink targets.
A. Mitosis B. Prophase C. Metaphase D. Anaphase, Telophase and Cytokinesis E. Meiosis F. Prophase I G. Metaphase I H. Anaphase I, Telophase I and Cytokinesis I. Meiosis II
Can you label the events and stages of mitosis?
A. Mitotic B. Sister Chromatids Centered C. Chromosomes Seperating D. Nuclear Envelopes Forming E. Interphase F. Prophase G. Metaphase H. Anaphase I. Telephase and cytokensis
What name is given to this process?To view the animation, click here. Then click on the image to start the animation. A) gametogenesis B) sexual reproduction C)meiosis D) asexual reproduction E) fertilization
Asexual reproduction
The first step of bacterial replication is
DNA replication
Use the graph and your knowledge of Down syndrome to select the three true statements.
Down syndrome is caused by a trisomy of chromosome 21. The incidence of Down syndrome in infants born to mothers under the age of 35 is less than 0.5%. The risk of having a baby with Down syndrome more than doubles for 45-year old mothers compared to 40-year old mothers.
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.
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.
Consider the photograph of a karyotype. This is _____.
a photograph of all a person's chromosomes
If a fragment of a chromosome breaks off and then reattaches to the original chromosome at the same place but in the reverse direction, the resulting chromosomal abnormality is called _____.
an inversion
Homologous chromosomes migrate to opposite poles during _____.
anaphase I
During _____ sister chromatids separate.
anaphase II
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
Down syndrome can be the result of _____.
c. (nondisjunction of chromosome 21 during meiosis)
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
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.
Polyploidy is involved in which of the following examples?
A normal watermelon has 22 chromosomes but seedless watermelons have 33 chromosomes.
Crossing over is important because it __________.
A. allows the exchange of different versions of genes between homologous chromosomes
Which of these cells is (are) haploid? 1) C and D 2) A and D 3) B and C 4) D 5) B
C and D
In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell culture. What is one explanation that could account for this?Cancer cells continue to die at a rate that is equal to their growth.Cancer cells are unable to attach to a surface and grow.Cancer cells continuously secrete growth factors into the cell culture medium.Cancer cells have inactive receptors for growth factors.
Cancer cells continuously secrete growth factors into the cell culture medium.
What is the difference between a benign tumor and malignant tumor?
Cells of benign tumors do not metastasize; those of malignant tumors do
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.
Gametes are produced by _____ .1) meiosis 2) fertilization 3) mitosis 4) the cell cycle 5) asexual reproduction
Meiosis
Variation occurs when chromosomes are shuffled in _____.
Meosis
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.
What must happen before a cell can begin mitosis?
The chromosomes must be duplicated, which occurs during interphase.
Consider the photograph shown below. You can determine this is a plant cell rather than an animal cell because it has _____.
formed a cell plate
Meiosis II typically produces _____ cells, each of which is _____.
four ... haploid
The function of meiosis is to make __________.
four cells with a haploid number of chromosomes
A cell replicates its entire chromosome DNA only before ______
its about to divide
During meiosis, homologous chromosomes sometimes "stick together" and do not separate properly. This phenomenon is known as _____.
nondisjunction
Synapsis occurs during _____.
prophase I
The exchange of parts between nonhomologous chromosomes is called _____.
reciprocal translocation
Meiosis I produces _____ cells, each of which is _____.
two ... haploid
True or false. Mitosis takes place during M phase of the cell cycle, which is longer than interphase.
False. Although mitosis takes place in M phase, M phase is shorter than interphase; cells spend most of their time in interphase.
Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X chromosome is not. What is the explanation for this difference?
Only one copy of the X chromosome is active, regardless of the total number of X chromosomes.