The strongest evidence for __________ comes from research showing that human cells allowed to divide in the laboratory have a lifespan of 50 divisions, plus or minus 10.
A) the existence of aging genes
B) the random events theory of aging
C) the cross-linkage theory of aging
D) behavioral modification of aging
Question 2
Noras grandfather lived to be 87, and her father is still alive at the age of 98. Nora concludes that longevity is inherited and anticipates a very long life. Nora should know that __________.
A) there is no reliable data on the heritability of longevity, so the cumulative effects of random events probably contributed to the long lives of her relatives
B) the lifespans of fraternal twins are just as similar as the lifespans of identical twins, indicating that longevity is probably not a heritable trait
C) rather than inheriting longevity directly, people probably inherit risk and protective factors that influence their chances of dying earlier or later
D) the heritability of longevity is high, ranging from .75 to .95 for age at death, indicating that longevity is directly related to genetic factors
Soil profile exposed in a boreal forest site, showing LFH, A, B, and C horizons.
Left: This web was woven by a 17-day-old spider, showing regular patterns. Right: This web was woven
The underbelly of a sand tiger shark, showing its pectoral fins
The face of a caterpillar with the mouthparts showing
BLOOD CELLS
human body