1. One condition that seems to lead to senescence and not apoptosis in stem cells is:

a. shortening of telomeres below a critical limit
b. base damage to DNA
c. unequal division of chromosomes at anaphase
d. none of the above

2. Knowing that even in the oldest people's stem cells seem to have many cell divisions left to them when cultured in vitro (in a dish), the you might contend that a possible reason for that was:

a. Absence of inhibitory factors found in the old bodies in the new culture medium
b. factors in the cellular environment of old people's bodies
c. The presence of high levels of growth factors in the culture serum
d. All of the above

3. In 1962, Leonard Hayflick conducted an experiment that supported Weismann's Theory of programmed death. He proposed The Hayflick Limit which can be reached faster by:

a. Increasing the rate of cell division
b. Underfeeding cells
c. Decreasing the rate of mutations
d. Synthetically elongating telomeres.

4. The antagonistic pleiotropy theory of aging assumes that each gene has only one effect on the phenotype of an organism at different stages of its life. True or False

5. In Conboy's study on heterochronic parabiotic pairs, which phrase described what future studies should focus on according to the results of this study?

a. adult stem cells
b. changes in aging cells
c. muscle cell regeneration
d. changes in aging plasma