Transport of photosynthetically produced sugars from leaves to roots occurs by _____
a. pressure flow
b. differences in source and sink solute concentrations
c. the pumping force of xylem vessels
d. transpiration, tension, and cohesion of water
e. pressure flow and differences in source and sink solute concentrations
E
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Which of the following contributed to the dust bowl in the American southwest during the 1930s?
I) overgrazing by cattle II) clear-cutting of forest trees III) plowing of native grasses IV) lack of soil moisture A) I and II B) II, III, and IV C) I, III, and IV D) I, II, III, IV
Tetralogy of Fallot (TF) is a genetic disorder characterized by four major malformations of the heart. The circulation of blood is abnormal, so TF patients have too little oxygen in their blood. Inadequate oxygen levels result in damaged mitochondrial membranes, which in turn cause cells to self-destruct. In 2004, Sarah Kuruvilla and her colleagues looked at abnormalities in the mitochondria of
heart muscle in TF patients. Some of their results are shown in Figure 7.13 (on previous slide). What conclusion do the data support about mitochondrial abnormalities and levels of oxygen saturation of the blood (SPO2)?
1.Abnormalities in size of mitochondria is not an important factor.
2.Abnormalities in number of mitochondria have a significant impact on SPO2.
3.The combination of broken mitochondria and abnormal numbers of mitochondria causes the lowest levels of SPO2.
4.Younger patients have lower levels of SPO2.
DDT was once considered a "silver bullet" that would permanently eradicate insect pests. Instead, DDT is largely useless against many insects. Which of these would have prevented this evolution of DDT resistance in insect pests?
A) All habitats should have received applications of DDT at about the same time. B) The frequency of DDT application should have been higher. C) None of the insect pests would have genetic variations that resulted in DDT resistance. D) DDT application should have been continual.
Which of the following best demonstrates the relationships between the different developmental processes?
a. Cell differentiation is the major driver of the other developmental processes b. Cell proliferation, on its own, can result in substantial changes to embryo shape c. In the absence of induction, most of the other developmental processes would be severely impaired or not occur d. Programmed cell death usually only occurs when needed to eliminate defective cells in an embryo