Complete the following table to compare mitosis and meiosis.

If an intestinal cell in a grasshopper contains 24 chromosomes, then a grasshopper sperm cell contains ___________ chromosomes.

a. 6

b. 12

c. 24

d. 48

Which of the following is not a function of mitosis in humans?

a. Repair of wounds

b. Growth

c. Production of gametes from diploid cells

d. Replacement of lost or damaged cells

It is difficult to observe individual chromosomes during interphase because

a. The DNA has not been replicated yet

b. They are in the form of long, thin strands

c. They leave the nucleus and are dispersed to other parts of the cell

d. Homologous chromosomes do not pair up until division starts

A fruit fly somatic cell contains 8 chromosomes. This means that ___________ different combinations of chromosomes are possible in its gametes.

a. 8

b. 16

c. 32

d. 64

If a fragment of a chromosome breaks off and then reattaches to the original chromosome but in the reverse direction, the resulting chromosomal abnormality is called

a. A deletion

b. An inversion

c. A translocation

d. A non-disjunction

Which of the following phases of mitosis is essentially the opposite of prophase in terms of changes within the nucleus?

a. Telophase

b. Metaphase

c. Interphase

d. Anaphase

A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in a cell doubled

a. Between prophase and anaphase of mitosis

b. Between the G1 and G2 phases of the cell cycle

c. During the M phase of the cell cycle

d. Between prophase I and prophase II of meiosis

A micrograph of a dividing cell from a mouse showed 19 chromosomes, each consisting of two sister chromatids. During which of the following stages of cell division could such a picture have been taken? (Explain your answer.)

a. Prophase of mitosis

b. Telophase II of meiosis

c. Prophase I of meiosis

d. Prophase II of meiosis

Cytochalasin B is a chemical that disrupts microfilament formation. This chemical would interfere with:

a. DNA replication

b. Formation of the mitotic spindle

c. Cleavage

d. Formation of the cell plate

Why are individuals with an extra chromosome 21, which causes Down syndrome, more numerous than individuals with an extra chromosome 3 or chromosome 16?

a. There are probably more genes on chromosome 21 than on the others.

b. Chromosome 21 is a sex chromosome, and chromosomes 3 and 16 are not.

c. Down syndrome is not more common, just more serious.

d. Extra copies of the other chromosomes are probably fatal.

In the light micrograph below of dividing cells near the tip of an onion root, identify a cell in interphase, prophase, metaphase, anaphase, and telophase. Describe the major events occurring at each stage.

<IMAGE>

Discuss the factors that control the division of eukaryotic cells grown in the laboratory. Cancer cells are easier to grow in the lab than other cells.

Why do you suppose this is?

Compare cytokinesis in plant and animal cells.

In what ways are the two processes similar?

In what ways are they different?

Sketch a cell with three pairs of chromosomes undergoing meiosis, and show how non-disjunction can result in the production of gametes with extra or missing chromosomes.

Suppose you read in the newspaper that a genetic engineering laboratory has developed a procedure for fusing two gametes from the same person (two eggs or two sperm) to form a zygote. The article mentions that an early step in the procedure prevents crossing over from occurring during the formation of the gametes in the donor's body. The researchers are in the process of determining the genetic makeup of one of their new zygotes. Which of the following predictions do you think they would make? Justify your choice, and explain why you rejected each of the other choices.

a. The zygote would have 46 chromosomes, all of which came from the gamete donor (its one parent), so the zygote would be genetically identical to the gamete donor.

b. The zygote could be genetically identical to the gamete donor, but it is much more likely that it would have an unpredictable mixture of chromosomes from the gamete donor's parents.

c. The zygote would not be genetically identical to the gamete donor, but it would be genetically identical to one of the donor's parents.

d. The zygote would not be genetically identical to the gamete donor, but it would be genetically identical to one of the donor's grandparents.

Bacteria are able to divide on a faster schedule than eukaryotic cells. Some bacteria can divide every 20 minutes, while the minimum time required by eukaryotic cells in a rapidly developing embryo is about once per hour, and most cells divide much less often than that. State at least two testable hypotheses explaining why bacteria can divide at a faster rate than eukaryotic cells.

Red blood cells, which carry oxygen to body tissues, live for only about 120 days. Replacement cells are produced by cell division in bone marrow.

How many cell divisions must occur each second in your bone marrow just to replace red blood cells? Here is some information to use in calculating your answer: There are about 5 million red blood cells per cubic millimeter (mm³) of blood. An average adult has about 5 L (5,000 cm³) of blood. (Hint: What is the total number of red blood cells in the body?

What fraction of them must be replaced each day if all are replaced in 120 days?

What you think of as 'a banana' is a Cavendish, one variety of the species Musa acuminate. It is a triploid organism (3n) with three sets of chromosomes in every somatic cell. The Cavendish cannot be naturally bred; it can only be reproduced by cloning. Explain how its triploid state accounts for its inability to form normal gametes. Discuss how the lack of sexual reproduction might make the species particularly vulnerable to a new pest.