The earliest cells on Earth were primitive anaerobic bacteria. Why were they anaerobic?
a. Oxygen gas was present in the atmosphere.
b. They had no photosynthetic pigments.
c. There was no oxygen gas in the early Earth's atmosphere.
d. Bacteria did not possess the complicated mechanisms required for other means of energy generation.
e. They required the heat produced by Earth's molten rock.
Ans: c. There was no oxygen gas in the early Earth's atmosphere.
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Which would be more likely to cause illness-a water sample that tested positive for coliforms or one that tested positive for E. coli O157:H7?
A. Both would be equally capable of causing illness-all coliforms cause illness. B. The coliform positive sample would be more likely to cause illness. Coliforms are inherently more pathogenic than the weak O157:H7 lab strain of E. coli. C. The E. coli O157:H7 sample would be more likely to cause illness. This strain of bacterium is highly pathogenic and capable of causing kidney damage. D. Neither-there is usually a small amount of coliforms (including E. coli O157:H7) in all water.
What evidence is there that choanoflagellates were the ancestors to animals? What will be an ideal response?
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, and the older the man, the older the sperm. Older sperm are more likely to experience a non disjunction 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.
Gene expression includes which of the following?
A) DNA replication B) replication, transcription, and translation C) transcription and translation D) translation only