Asexual and sexual reproduction differ in that sexual reproduction _____. |
can produce great variation among the offspring |
Consider the process by which bacterial populations grow. What process performs a similar |
mitosis |
During binary fission, the replicated bacterial chromosome attaches to the plasma membrane |
It ensures the separation of the replicated chromosomes as new membrane is made. |
Within one chromosome, what is the relationship between the sequence of bases in DNA of one |
The sequences are identical. |
Which of the following statements correctly describes the timing of DNA synthesis? |
DNA is synthesized in the S phase of interphase. |
What would be the immediate consequence of destroying a cell's centrosomes? |
The mitotic spindle would not form. |
During mitosis, the chromosomes move because _____. |
they attach to a dynamic, precisely regulated mitotic spindle |
A cell is treated with a drug that prevents the formation of intracellular (within the cell) |
cytokinesis in a plant cell |
In the laboratory, cancer cells fail to show density-dependent inhibition of growth in cell |
Cancer cells continuously secrete growth factors into the cell culture medium. |
When examining cells in the laboratory, you notice that a particular cell has half as much DNA |
G1 |
A benign and a malignant tumor differ in that _____. |
cells of a benign tumor remain within the tumor, whereas cells of a malignant tumor can spread to other body tissues |
When forming buds, hydras _____. |
divide by mitosis |
In many organisms, including humans, chromosomes are found in homologous pairs. |
are identical in the arrangement of their genes, but some versions of the genes may differ between the chromosomes |
Baker's yeast is an organism with 32 chromosomes that can perform asexual or sexual |
16 |
The M phase of mitosis and M phase of meiosis both occur after interphase. However, the two |
The pairing up of homologous chromosomes and crossing over only occur during meiosis. |
At the conclusion of meiosis I, the daughter cells are _____. |
haploid and the sister chromatids are joined |
In meiosis II, _____. |
sister chromatids are separated |
If we assume that crossing over does not occur, how many different combinations of chromosomes are possible in a zygote derived from diploid parents who have 3 pairs of of chromosomes? |
64 Correct. Each gamete can have eight different combinations of parental chromosomes (2n, or 23). There are 8 × 8 = 64 different combinations possible for the zygote. |
Inbreeding has a number of interesting effects. For one, highly inbred strains (varieties) may |
1 |
During meiosis I, homologous chromosomes form a tetrad. What does this accomplish? |
This brings the chromosomes into alignment so that crossing over can create new combinations of genes present on a single chromosome. |
In a cell with eight chromosomes, one chiasma develops during meiosis I in only one particular |
two |
Scientists commonly choose white blood cells that are going through mitosis to prepare |
During mitosis, chromosomes are more condensed than during interphase. |
Although in humans there are 22 pairs of autosomal chromosomes, only three different chromosomal trisomies are commonly seen in newborns. Of the remaining 19 autosomes, |
Trisomy for the other autosomal chromosomes is often lethal, and the affected embryos are miscarried. |
In theory, when a nondisjunction for chromosome 18 occurs during meiosis I, four gametes |
Two of the embryos will be trisomic for chromosome 18, and two will contain a single copy of chromosome 18. |
Trisomy for most autosomes is fatal, yet trisomy or even tetrasomy (four copies) of the X |
Only one copy of the X chromosome is active, regardless of the total number of X chromosomes. |
You suspect that a serious developmental disorder is due to a chromosome abnormality and |
In trisomy there would be one extra chromosome; in a duplication, one chromosome would have two copies of a portion of the chromosome. |