20. Which of the following statements is *NOT* true?
a) The cells resulting from meiosis are diploid and the cells resulting from mitosis are haploid.
b) Meiosis and meiosis both starts with one cell, but meiosis ends with four and mitosis with two.
c) Mitosis produces new cells for growth and repair, meiosis produces gametes.
d) Mitosis goes through cytokinesis once, meiosis goes through cytokinesis twice.
e) Cross over happens in meiosis, but not in mitosis.
21. In the scientific method, a hypothesis ____________.
a) is a statement of fact
b) is a proposed explanation based on observations
c) is usually proven to be correct
d) can only be tested once
e) all of the above
22. To test a hypothesis about a given variable, experimental and control groups are tested in parallel. Which of the following best explains the dual experiments?
a) In the experimental group, a chosen variable is altered in a known way. In the control group, that chosen variable is not altered so a comparison can be made.
b) In the control group, a chosen variable is altered in a known way. In the experimental group, that chosen variable is not altered so a comparison can be made.
c) In the experimental group, a chosen variable plus all other variables are altered. In the control group, the chosen variable is altered; however, all other variables are held constant.
d) In the experimental and control groups, two different variables are altered.
e) Experimental and control group experiments are identical and run in parallel to get repeatable results.

The sexually transmissible disease gonorrhea has become increasingly resistant to treatment with antibiotics. What is the most likely scientific explanation?
a) The gonorrhea bacteria learned to avoid antibiotics
b) The gonorrhea bacteria changed their genes when they sensed antibiotics
c) Antibiotic-sensitive gonorrhea bacteria died out, but antibiotic-resistant gonorrhea bacteria have flourished and persisted
d) The antibiotic increased the mutation rate in the gonorrhea bacteria
e) Both b and d