Regents Review 3

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

• A tree synthesizes starch from simpler molecules.

• A bacterial cell performs photosynthesis.

• A bird digests proteins from its food.

• A fungus breaks down the body of a dead animal.

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Itching and other skin problems are signs that a cat or dog may have fl eas. Fleas are parasites known for their biting and blood-sucking abilities. When they bite, fl ea 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

• flea saliva may stimulate an immune response in cats and dogs

• fleas are microbes whose bites cause a decreased blood flow

• flea saliva is a toxic substance that is released when fleas prey on cats and dogs

• fleas are host organisms whose saliva digests cat and dog fur, leaving "hot spots"

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

• the development of rubella virus infections in embryos

• the failure of zygotes infected with rubella to develop

• mutations in the nerve cells of pregnant females at the time of the rubella epidemic

• an increase in the amount of time needed for healthy embryonic development

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

• the primary source of oxygen for the mother

• where the fetus obtains milk from the mother

• where nutrients and wastes are exchanged

• the primary source of estrogen and progesterone in the mother

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

• carbon dioxide that enters through the leaf openings

• oxygen that enters through the leaf openings

• soil that all plants need to grow

• chloroplasts that enter the roots and move to the leaves

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Recently, a type of genetically modified fi sh has been approved for sale for human consumption. The modified fi sh contain a growth hormone gene from a different fish species. As a result, the modified fi sh 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

• each of their cells contains the new gene to produce growth hormone

• each gene contains the code to synthesize carbohydrates

• the altered gene directs the mitochondria to synthesize the hormone

• the modifi ed body cells are able to reproduce by meiosis

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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

• require everyone to remain indoors during daylight hours

• regulate the production and release of gases that damage the ozone shield

• encourage the building of a greater number of cancer treatment centers

• prohibit the use of solar panels on homes and businesses

Some birds have recently modifi ed their migratory behavior. Instead of fl ying to warmer climates during the winter months, the birds are remaining in northern areas where they can consume discarded food that is abundant in landfi lls. 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

• interfering with ecological succession

• increasing competition for infi nite resources

• disrupting the homeostasis of organisms

• altering the equilibrium of ecosystems

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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

• encourage people to spend more money on their beverages

• conserve the resources these containers are made from

• reduce the amount of carbon dioxide produced by deforestation

• totally eliminate the use of reusable containers

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Recently, a human trachea (a respiratory organ) was produced by using a patient’s own stem cells. The benefi t of using the patient’s own cells to produce a trachea instead of receiving one from a donor is that

• there will be more enzymes produced to help maintain homeostasis in the trachea

• there will be an increase in the quantity of antibodies that the patient produces in response to the new trachea

• there is less of a chance that the patient’s immune system will attack the trachea

• there will be a greater response to any infectious agent that may enter the body