Question

1. by the end of prophase, all of the following has occurred except

a. the nuclear membrane has broken down
b. centrioles and spindle fibers have appeared
c. chromosomes have lined up in the middle of the cell
d. dna has become more tightly coiled into rod - shaped structures

1. substances known to produce or promote cancer are called

a. carcinogens b. kinases c. cyclins d. malignancies

1. one difference between a cancer cell and a normal cell is that

a. cancer cells divide uncontrollably b. normal cells divide uncontrollably
c. cancer cells cannot make copies of dna d. normal cells cannot make copies of dna
concept 3 open response

1. if a cell does not go through the s phase of the cell cycle before mitosis, what might be wrong with the daughter cells? (1 pt)
2. what are two purposes of the cell cycle? (1 pt)
3. beginning with prophase, list the parts of mitosis in order and give a brief description of what happens in each phase. (1 pt)

cumulative multiple choice (2 pts each)

1. a group of students wants to find out how heat affects the rate of chemical reactions. they use hydrogen peroxide, which breaks down into oxygen and water, for their experiment. the student measured how long it took to obtain 50 ml of water when the hydrogen peroxide was heated at different temperatures. they used the same amount of hydrogen peroxide for each test and measured the time it took for each sample to produce 50 ml of water. the data is shown to the right.

based on the data in the table above, what conclusions can be drawn?
a. heat does not affect the rates of the breakdown of hydrogen peroxide into oxygen and water.
b. the more time that passes, the lower the temperature of the reaction.
c. heat increases how long it takes to breakdown hydrogen peroxide into oxygen and water.
d. heat decreases how long it takes to breakdown hydrogen peroxide into oxygen and water.

1. in a hypothesis the ________ variable is what is being tested, while the ________ variable is the one being measured in response.

a. control; dependent b. dependent; independent
c. independent; control d. independent; dependent

1. what is the independent variable in the following hypothesis: \if carbon dioxide is added to the atmosphere, then the temperature of the earth will rise.\

a. presence of carbon dioxide b. the earth
c. temperature of the earth d. the atmosphere

1. substances that dislike water are considered ________ and substances that like water are ________

a. hydrophilic; hydrophobic b. hydrophobic; hydrophilic
c. hydrophilic; polar d. hydrophobic; nonpolar

Explanation:

1. Chromosomes line up in the middle during metaphase, not prophase.
2. Carcinogens are substances that produce or promote cancer.
3. Cancer cells divide uncontrollably while normal cells divide in a regulated way.
4. If the S - phase (DNA replication) is skipped before mitosis, daughter cells will have half the normal amount of DNA.
5. The cell cycle has two main purposes: growth and repair of the organism and asexual reproduction.
6. Prophase: chromatin condenses into chromosomes, nuclear membrane breaks down, centrioles and spindle fibers appear. Metaphase: chromosomes line up in the middle of the cell. Anaphase: sister chromatids are pulled apart to opposite poles. Telophase: nuclear membranes reform around the separated chromosomes, chromosomes de - condense.
7. As the temperature increases, the time to break down hydrogen peroxide decreases, so heat increases the rate of the reaction.
8. In a hypothesis, the independent variable is what is being tested, and the dependent variable is the one measured in response.
9. The independent variable in the hypothesis "If carbon dioxide is added to the atmosphere, then the temperature of the Earth will rise." is the presence of carbon dioxide.
10. Substances that dislike water are hydrophobic and substances that like water are hydrophilic.

Answer:

1. C
2. A
3. A
4. Daughter cells will have half the normal amount of DNA.
5. Growth, repair and asexual reproduction.
6. Prophase: Chromatin condenses, nuclear membrane breaks down. Metaphase: Chromosomes line up. Anaphase: Sister chromatids separate. Telophase: Nuclear membranes reform.
7. D
8. D
9. A
10. B