According to the animation, where on the DNA strand does a repressor bind?
a. The inducer
b. The operator
c. The promoter
d. The structural genes
Answer: b. The operator
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Even in the absence of transpiration, some water can move into the roots and partially up the xylem columns. This phenomenon is due to
A. flooding. B. stomatal opening. C. root pressure. D. proton pumps. E. phloem translocation.
Which of the following is not one of the key adaptations that distinguish hominins from apes?
1.bipedal locomotion
2.opposable thumbs
3.upright posture
4.tool use
Leptin is a circulating hormone that is produced by fat cells and plays a role in body metabolism and obesity. It normally binds to receptors in the brain and inhibits appetite. Studies have demonstrated that when obese mice that are leptin deficient are injected with leptin they quickly lose their excess weight. Interestingly, however, many overweight people have high levels of leptin in their bloodstream. Why do you think that the high levels of leptin in obese individuals are insufficient to curb their appetite?
A. In obese people with high levels of leptin, the leptin is a non-functional second messenger. B. The form of leptin released by obese people may lack protein kinase activity. C. Obese people who have high levels of leptin may have a leptin receptor with decreased sensitivity. D. Paracrine signaling may be disrupted in obese people with high levels of leptin.
Most plants are known as photoheterotrophs. Indicate whether the statement is true or false