A
Humans have been consuming natural plant pesticides for millennia and have had time to adapt to them.
B
The concentrations of natural pesticides in plants are typically much lower than the concentrations of synthetic pesticides in sprayed crop plants.
C
Natural plant pesticides are typically less potent than synthetic pesticides, whose toxicity is highly concentrated.
D
Natural plant pesticides generally serve only as defenses against specific parasites, whereas synthetic pesticides are often harmful to a wide variety of organisms.
E
The synthetic pesticides sprayed on crop plants by humans usually have chemical structures similar to those of the natural pesticides produced by the plants.
Before their larvae hatch, each parental pair of Nicrophorus beetles buries the carcass of a small vertebrate nearby. For several days after the larvae hatch, both beetles feed their voracious larvae from the carcass, which is entirely consumed within a week. Since both parents help with feeding, larvae should benefit from both parents’ presence; however, removing one parent before the hatching results in larvae that grow both larger and heavier than they otherwise would be.
"Surprising" Phenomenon
Why do the larva grow larger and heavier when one parent is present, even though both parents help with feeding by bringing a food source to the larva before they hatch?
Objective
The correct answer should help explain why having one parent present present is better for the larva’s growth than having two parents. Perhaps, for example, having two parents takes away from the amount of food available to the larva, or causes some kind of biological reaction in the larva that inhibits their growth. Or perhaps there’s something about having one parent present that leads larva to eat more.
A
Two beetles can find and bury a larger carcass than can a single beetle.
This makes the discrepancy harder to explain, because it’s something positive about having two parents present compared to only one.
B
Both parents use the carcass as their own food supply for as long as they stay with the larvae.
If both parents use the carcass for their own food, that leave less food available for the larva when both parents are present compared to when only one is present. That could explain why the larva grow larger with only one present.
C
Beetle parents usually take turns feeding their larvae, so that there is always one provider available and one at rest.
This doesn’t tell us why having both parents present would lead to less food for the larva. If anything, it suggests having both present would help the larva feed, which makes the discrepancy harder to explain.
D
After a week, the larvae are capable of finding other sources of food and feeding themselves.
But why would having two parents around be worse for larva growth than having only one present? This doesn’t differentiate between having both parents around compared to only one.
E
Two parents can defend the carcass from attack by other insects better than a single parent can.
This is a reason to think larva should have more food available when both parents are present than when only one is present. This makes the discrepancy harder to explain.
A
Scientists who use Euclidean geometry are likely to believe that progress in mathematical theory results in progress in natural science.
B
Scientists generally do not now believe that classical Euclidean geometry is uniquely capable of giving a correct mathematical representation of the universe.
C
Non-Euclidean geometry is a more complete way of representing the universe than is Euclidean geometry.
D
An accurate scientific theory cannot be developed without the discovery of a uniquely correct way of mathematically representing the universe.
E
The usefulness of a mathematical theory is now considered by scientists to be more important than its mathematical correctness.
A
It gives only one example of a tidal range.
B
It fails to consider that the size of a tidal range could be affected by the conditions in which gravitational forces act.
C
It does not consider the possibility that low tides are measured in a different way than are high tides.
D
It presumes, without providing warrant, that most activity within the world’s oceans is a result of an interplay of gravitational forces.
E
It does not differentiate between the tidal effect of the sun and the tidal effect of the moon.
Cardiologist: Coronary bypass surgery is commonly performed on patients suffering from coronary artery disease when certain other therapies would be as effective. Besides being relatively inexpensive, these other therapies pose less risk to the patient since they are less intrusive. Bypass surgery is especially debatable for single-vessel disease.
Summary
Coronary bypass surgery is performed on patients with coronary artery disease when other treatments would be as effective. The other therapies are less expensive and pose less risk to the patient. These concerns are especially high for single-vessel disease.
Strongly Supported Conclusions
It is likely that therapies other than coronary bypass surgery would be as effective for conditions like single-vessel disease while posing less risk and cost to the patient.
A
Bypass surgery is riskier than all alternative therapies.
This is unsupported because the author only states that there are some therapies with less risk than coronary bypass surgery, not that all therapies are less risky. There could be other therapies with much greater risk that are not discussed.
B
Needless bypass surgery is more common today than previously.
This is unsupported because the author provides no information about the frequency of different surgeries over time.
C
Bypass surgery should be performed when more than one vessel is diseased.
This is unsupported because although the author said bypass surgery is especially debatable for single-vessel disease, the author leaves open the possibility that bypass surgery is also too risky for diseases of multiple vessels.
D
Bypass surgery is an especially expensive therapy when used to treat single-vessel disease.
This is unsupported because while we know that bypass surgery is especially debatable for single-vessel disease, we don’t know if this is due to cost or risk.
E
Sometimes there are equally effective alternatives to bypass surgery that involve less risk.
This is strongly supported because the stimulus indicates that other therapies are as effective as bypass surgeries and that these therapies involve lower risk.