About 99 percent of the UV radiation that the sun showers on Earth is blocked by:
A) the magnetic fields that surround the Earth.
B) stratospheric ozone.
C) ground level ozone.
D) stratospheric greenhouse gases, such as CO2 and water.
E) tropospheric greenhouse gases, such as CO2 and water.
Answer: B
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Characters that are similar because of descent from a common ancestor are _____; characters that are similar due to convergent evolution are _____
A. homologous; analogous B. analogous; homologous
When comparing specialist species with generalist species, it may be said that
a. generalist species will survive in fewer habitats than specialist species. b. generalist species are at a disadvantage when comparing niches. c. generalist species will most likely be at an advantage when it comes to adaptation in situations where the environment is changing. d. specialist species have a more diverse nutritional source list. e. specialist species exhibit a broad range of habitats.
Bacteria divide asexually by mitosis
__________________ Indicate whether the statement is true or false.
A 30-year-old woman has a 1 in 3,000 chance of giving birth to a child with trisomy 21; however, a 48-year-old woman has a 1 in 9 chance. Which statement is the most likely explanation for why a woman has a higher probability of giving birth to a child with trisomy 21 as she ages?
A) Older women are more likely to mate with older men, an d the older the man, the older the sperm. Older sperm are more likely to experience a nondisjunction event during meiosis. B) Older women have older oocytes, and the older the oocytes, the greater the chance they will experience a nondisjunction event during meiosis. C) Older women have lived longer and have an increased percentage of toxins and oxidative damage in their bodies. Because these are the major causes of trisomy 21, the likelihood of giving birth to a child with trisomy 21 increases. D) Older women have older oocytes, and the older the oocytes, the greater the chance they will experience failure of cytokinesis during cell division. E) Older women have older oocytes, and the older the oocytes, the greater the chance that sister chromatids will fail to separate during meiosis I.