A city was intensively sprayed with DDT to control houseflies. The number of houseflies was immediately greatly reduced
Each year thereafter, the city was sprayed again, but the flies gradually increased in numbers until 10 years later, when they were almost as abundant as they were when the control program began. Which explanation applies to this situation? A) Flies from other areas moved in and replaced the ones killed by DDT.
B) The few flies that were affected by DDT but survived developed antibodies to DDT, which they passed on to their descendants.
C) The DDT caused new mutations to occur in the surviving flies, resulting in resistance to DDT.
D) The DDT killed most flies. The few that were already naturally resistant survived and passed this resistance on to their offspring.
D
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In analyzing microarray data if the ratio of mRNA present before and after a particular treatment is 1 it indicates that
A. there was no change in mRNA levels before and after treatment B. the gene was not expressed either before or after treatment. C. gene expression could not be detected. D. mRNA was not detected before treatment.
Which of the following may be added to normal media to make it more selective for staphylococci?
A. 7.5% salt B. 0.5% HCl C. 1.0% glucose D. 5.0% mannose
Which of the following do yeast produce during fermentation?
A. Glucose. B. Pyruvate. C. Ethanol. D. Lactate. E. NADH.
Which of the following statements best describes the difference between mitosomes and mitochondria?
A. Mitosomes contain hydrolytic enzymes that help the protozoan digest food particles. B. Mitosomes are much larger than mitochondria. C. Mitosomes have one membrane whereas mitochondria have a double membrane. D. Mitosomes are not involved in ATP production.