New York State Chemistry RegentsNew York State Earth Science Regents

NYS Living Environment Regents August 2010
Living Environment Regents August 2010 Question 21 PDF Print E-mail
Friday, 27 May 2011 13:00

Correct answer: (2) maintain homeostasis

Homeostasis is the steady-state physiological condition of the body. Plants maintain homeostasis through the use of different mechanisms and structures such as the stoma (stomates, plural). The guard cells of the stomates mediate the balance between transpiration and photosynthesis. Through photosynthesis, carbon dioxide and water are converted into glucose and oxygen. Transpiration, on the other hand, is the evaporative loss of water from the plant. The stomates are in charge of getting rid of excess water in the plant. When there is too much water, the guard cells open to evaporate water. When there is water deficiency, abscisic acid signals the guard cells to close the stomates.

Incorrect answers:

(1) produce light energy

Chloroplasts are the organelles that absorb light energy produced by the sun and use that energy to drive the synthesis of organic compounds from carbon dioxide and water.

(3) decompose organic matter

The stomates are not involved in decomposition. Decomposers, such as fungi and bacteria, are the organisms that break down dead organic materials from plants and animals, and convert them into inorganic forms.

(4) synthesize minerals

Stomates do not synthesize minerals. Minerals found in plants usually come from the soil, absorbed through the roots.
Last Updated on Friday, 27 May 2011 13:11
Living Environment Regents August 2010 Question 22 PDF Print E-mail
Friday, 27 May 2011 13:12

Correct answer: (4) no competition between species

An ecosystem can be considered stable when the resources in the surroundings are enough to maintain diversity and populations. This is usually achieved before the ecosystem reaches its carrying capacity, or the maximum population size that can be supported by the available resources. There is no competition among species when there is ample amount of resources in the ecosystem to make populations maintain their numbers.

Incorrect answers:

(1) predators that outnumber their prey

When predators outnumber the prey, there would be substantial competition on the prey in order for the predators to survive. This will cause the decrease in the number of predators. Therefore, the ecosystem is not stable or in equilibrium.

(2) a continual input of energy

There is a continual input of energy when autotrophic organisms continuously produce energy through sunlight. However, the continuous input of energy cannot be equated with the continuous flow of energy (Did you mean "the continuous inflow of energy cannot be equated with the continuous outflow of energy"?). A stable ecosystem is characterized by the continuous flow of energy from one trophic level to another.

(3) limited autotrophic nutrition

Autotrophic organisms, also known as producers, comprise the base of a community's energy pyramid. When there is limited autotrophic nutrition, the organisms that prey on plants would compete with the limited resources. Thus, the ecosystem is not stable.
Living Environment Regents August 2010 Question 23 PDF Print E-mail
Friday, 27 May 2011 13:18

Correct answer: (3) selective breeding

It is possible that the Seattle Slew was bred to be fast by selective breeding. Since both parents carry the genes for being fast, then there is high probability that the offspring also exhibit the same trait.

Incorrect answers:

(1) environmental selection

Natural or environmental selection refers to the differential success in the reproduction of different phenotypes resulting from the interaction of organisms with their environment. This kind of selection is usually random, driven by survival of species.  This could lead to evolution or speciation; however, both would take a long time to be evident.

(2) alteration of DNA molecules

The alteration of DNA molecules is also known as genetic engineering, usually done by inserting one or more desirable traits into an organism through the recombinant DNA technology. The genes that confer the desired trait usually come from a different species that cannot interbreed with the transgenic organism. Seattle Slew is not genetically altered to be fast because both parents already exhibit the desired trait.

(4) a sudden mutation

Mutation is the rare change in the DNA of genes that ultimately creates genetic diversity. Since both parents exhibit the same trait, mutation unlikely explains the presence of the trait.
Living Environment Regents August 2010 Question 24 PDF Print E-mail
Friday, 27 May 2011 13:22

Correct answer: (1) stable ecosystem that can last for many years

The community illustrated went through an ecological succession, or transition of species compositions over time. The community passed through a sequence of predictable transitional stages until it reached a relatively stable state called a climax community. During this stage, there will be minimal changes in the composition of species in the community because the resources are abundant and the environment is suitable for the survival of most species.

Incorrect answers:

(2) lost heterotrophs that cannot be recovered

Heterotrophs are organisms that obtain organic food molecules by eating other organisms or their by-products. When a climax community is been reached, all the trophic levels are filled up to maintain the stability of the community. If heterotrophic organisms are absent, climax community would not be achieved.

(3) long-term rise in environmental temperatures

Temperature is an abiotic factor that depends on the amount of sunlight that can enter on the earth's atmosphere. A climax community is usually characterized by the predominance of trees that serve as shade for shade-loving plants and other forms of wildlife that cannot tolerate the extreme heat of the sun. Thus, when climax community is reached, the temperature under the canopy of the trees is decreased.

(4) forest consisting of only producers and decomposers

A climax community is composed of not just producers and decomposers but also a number of consumers. This state is reached only when all the trophic levels are present, meaning there are producers, consumers, and decomposers.
Living Environment Regents August 2010 Question 25 PDF Print E-mail
Friday, 27 May 2011 13:24

Correct answer: (2) Blood flow throughout the entire body is suddenly reduced.

When blood flow is suddenly reduced, the individual encounters cardiac arrest, which is caused by the failure of the heart (an organ) to contract. Since the blood carries oxygen to the other parts of the body, such as the brain, this may also cause loss of consciousness and abnormal breathing. If this lasts for several minutes, it may cause brain injury.

Incorrect answers:

(1) The ovary releases estrogen, which quickly binds to cell receptors.

This is a normal biological condition. Ovary releases estrogen that binds to its receptors.

(3) White blood cells release enzymes in response to the proteins on inhaled pollen.

White blood cells are blood components responsible for fighting infections, such as allergy-causing pollens.

(4) Mitochondria stop functioning in unicellular organism exposed to pollutants

Organs are absent in unicellular organisms, thus organ failure cannot occur in these organisms.
Living Environment Regents August 2010 Question 26 PDF Print E-mail
Friday, 27 May 2011 13:26

Correct answer: (1) bacteria and fungi

Ecological niche is the sum total of an organism's utilization of the biotic and abiotic resources of its environment. Since both bacteria and fungi belong to the same trophic level (decomposers), they most likely compete with each other in habitat and on resources in order to survive.

Incorrect answers:

(2) deer and wolf

Deer and wolf have different niche basically because they have different modes of nutrition. Deer are herbivorous, meaning they eat plants to get energy; while wolf are omnivorous, eating meat of other organisms to derive energy.

(3) tree and fungi

Tree and fungi also belong to different niches because they have different ways of using up the resources around them. For instance, trees use the sunlight to convert carbon dioxide and water to glucose and oxygen. On the other hand, fungi, which are decomposers, absorb nutrients from  nonliving organic material and convert them into inorganic forms.

(4) deer and bacteria

Deer and bacteria cannot compete on the same niche because they have different roles in the ecosystem. Bacteria serve as decomposers while deer are herbivores.
Living Environment Regents August 2010 Question 27 PDF Print E-mail
Friday, 27 May 2011 13:31

Correct answer: (2) There are few native predators of rabbits.

When there are few predators of an organism, then that organism faces less risk in survival. Reproduction rate would be high, and mortality rate (usually caused by predation or shortage of food) would be low.

Incorrect answers:

(1) Rabbits have a high metabolic rate.

The higher the speed of metabolism, the more food would be needed in order for the population of rabbits to survive. Thus, metabolic rate is not a factor in the predominance of rabbits in the area.

(3) Additional rabbit species have been introduced.

If additional rabbit species were introduced, then there would be more species to compete with the resources available. This will eventually lead to death of some rabbits, instead of increase in number.

(4) There is an increase in rabbit competitors.

If there are many competitors for the rabbits, then there would be shortage of food, which may lead to death of a number of rabbits and its competitors.
Living Environment Regents August 2010 Question 28 PDF Print E-mail
Friday, 27 May 2011 13:34

Correct answer: (3) recycling aluminum

Aluminum recycling is the process in which scrap aluminum is reused after its primary production. Aluminum is the most abundant metal in the earth's crust. However, a great amount of energy is required to extract it from ore. Thus, when aluminum is recycled, a lot of energy is saved, as well as the aluminum deposits in the crust.

Incorrect answers:

(1) deforestation

Deforestation is the removal of trees from the forest due to agricultural practices or urbanization. Although trees are considered as renewable resources, it takes years for trees to grow and replace those that are cut.

(2) removing carnivores from a forest

If carnivores are removed in the forest, there would be an ecological imbalance because they are important in the transfer of energy from one group of organism to another.

(4) heating homes with fossil fuels

Fossil fuels are considered as non-renewable resources because they cannot be replaced naturally in the amount of time taken to consume them. Thus, heating homes with the use of fossil fuels would not preserve the limited amount of fossil fuels in the environment.
Living Environment Regents August 2010 Question 29 PDF Print E-mail
Friday, 27 May 2011 13:37

Correct answer: (1) ecological succession

A previously disturbed area may be colonized by a variety of species, which are gradually replaced by others. Such change in species composition over ecological time represents the process known as ecological succession. In the situation given, the railroad, which was previously a bustling place, became abandoned. This caused the community to change. It transformed from a community of weeds into a community dominated by aspen trees.

Incorrect answers:

(2) biological evolution

Biological evolution refers to the natural genetic change in a species over time. The weed did not genetically change to become an aspen tree, thus the situation given is not an example of evolution.

(3) genetic variation

Genetic variation pertains to the difference in genetic makeup of a certain group of species.

(4) heterotrophic nutrition

Heterotrophic nutrition refers to the mode of nutrition of organisms that obtain organic food molecules by eating other organisms or other products. There are no heterotrophic organisms mentioned in the situation given because both weeds and aspen trees are autotrophic (organisms that produce their own food via photosynthesis).
Living Environment Regents August 2010 Question 30 PDF Print E-mail
Friday, 27 May 2011 13:40

Correct answer: (2) reducing the human population

Reducing the human population would do not harm to the lives of endangered species. It could be beneficial to them in so many ways. The major causes of the endangerment of species are habitat destruction, introduction of exotic species, and overexploitation. These factors are all effects of the increased human activity due to an increase in human population. For instance, wildlife habitats are disturbed when areas of land are developed into subdivisions or used to build factories. Or, humans bring exotic species to a new location where there could be few predators for those exotic species. Thus, the exotic species compete with the existing species-and since there are few predators, the exotic species replace the existing species that are in the same niche with the exotic species.

Incorrect answers:

(1) releasing more carbon dioxide into the atmosphere

Releasing more carbon dioxide in the atmosphere would cause greenhouse effect, and thus, climate change. This impacts the whole biosphere, most especially the endangered species.

(3) decreasing the amount of dissolved oxygen in the oceans

Decreasing the amount of dissolved oxygen in the oceans will harm the endangered species especially those that inhabit the ocean. Aquatic animals take in dissolved oxygen during respiration.

(4) reducing the thickness of the ozone layer

The ozone layer absorbs the ultraviolet rays of the sun, which is detrimental to living organisms. Thus, when this layer of gas becomes thinner, more ultraviolet rays would pierce the Earth's lower atmosphere and cause harm to living organisms, especially the endangered ones.
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