Which activity is an example of a decomposer recycling organic compounds back into the environment?*

Itching and other skin problems are signs that a cat or dog may have fleas. Fleas are parasites known for their biting and blood-sucking abilities. When they bite, flea saliva enters the pet’s circulatory system, sometimes causing an allergic response commonly seen as a “hot spot” on the pet’s neck or the base of its tail.

These observations are best explained by the fact that*

A German measles (rubella) epidemic during the years 1963 to 1965 resulted in approximately 30,000 babies being born with birth defects. The specific cause of these birth defects was most likely*

Placenta previa is a medical condition that occurs in some pregnant women. Women with this condition are often placed on bed rest, which prohibits them from any strenuous activity that may cause the blood vessels in the placenta to rupture. If not diagnosed, placenta previa can be a very dangerous condition because the placenta is*

Over time, a tree that once had a total mass of 300 g increased in mass to 3000 kg. This increase in mass comes mostly from*

Recently, a type of genetically modified fish has been approved for sale for human consumption. The modified fish contain a growth hormone gene from a different fish species. As a result, the modified fish grow rapidly and are ready to sell in almost half the time it normally would take. The modified fish are able to produce the new growth hormone because*

Melanoma is a type of skin cancer that can spread to vital organs in the body. Doctors believe that exposure to ultraviolet (UV) radiation from the Sun is a leading cause of melanoma. One practical way governments can help prevent the harmful effects of UV radiation is to*

Some birds have recently modified their migratory behavior. Instead of flying to warmer climates during the winter months, the birds are remaining in northern areas where they can consume discarded food that is abundant in landfills. As a result of this change in migratory behavior, many insect populations that the birds normally feed on in the warmer climate areas are now increasing. This is an example of human activity*

New York State charges consumers a fee when purchasing beverages sold in aluminum cans and plastic bottles. This money is returned to purchasers when they return these items for recycling. Programs such as these are an attempt to*

Recently, a human trachea (a respiratory organ) was produced by using a patient’s own stem cells. The benefit of using the patient’s own cells to produce a trachea instead of receiving one from a donor is that*

The diagram below represents the organization of structures within an organism.

Which term best indicates the structures represented by the circle labeled X?*

The chart below shows a comparison of the blood sugar levels for two individuals who took part in a scientific study.

Scientists have observed that blood sugar levels rose by different amounts in the two individuals even though they were given identical portions of bananas and cookies. These results were obtained because*

Which row in the chart below correctly matches the human activity with its effect?

*

Potatoes are an example of a crop that can be reproduced asexually. One potato will produce a number of “eyes,” which are sprouts that can grow into new plants. A potato with four eyes can be cut into four pieces, and each piece can be used to produce an individual potato plant.

A gardener could produce a small crop of potatoes by planting the eyes from a single potato in her garden. Some of the potatoes grown in this way could be used to obtain eyes for the next season’s crop.

One likely disadvantage of growing potatoes cloned in this way, year after year, would be that*

The back of the Namib Desert darkling beetle, shown in the photograph below, is covered in little bumps that collect water from the air. When it tilts forward, the water runs off its back into its mouth.

These specialized structures on the beetle’s back allow it to*