New York State Chemistry RegentsNew York State Earth Science Regents

 
Ecology
Living Environment Regents June 2010 Question 01 PDF Print E-mail
Thursday, 26 May 2011 14:35
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Correct Answer: (4) It obtains nutrients from its environment.

Heterotrophs are organisms that obtain organic food molecules by eating other organisms or their by-products, unlike autotrophs, which can produce their own food by converting light energy from the sun into chemical energy through photosynthesis. Mushroom spores grow on their food (e.g. wood, soil), from which they absorb organic matter to derive energy.

Incorrect Answers:

(1)   It manufactures its own food.

Mushrooms produce food by absorbing organic matter from their substrate to obtain energy. It cannot produce food on its own unlike plants and algae that gather light energy and transform it into chemical energy through photosynthesis. Organisms that can produce their own food are called autotrophs.

(2)   It divides by mitosis.

Heterotrophic refers to a characteristic of organisms that function through a certain mode of nutrition wherein they obtain energy by absorbing nutrients from living or dead matter. On the other hand, mitosis is a type of cell division wherein the chromosome number of the offspring is the same with their parents'. The type of cell division has no direct link on the mode of nutrition of organisms.

(3)   It transforms light energy into chemical energy,

Organisms that have the ability to transform light energy into chemical energy are called autotrophs ("autos" means self and "trophe" means nutrition in Greek). Mushrooms cannot absorb light energy to make its own food, thus they are not considered as autotrophs.
Last Updated on Thursday, 26 May 2011 14:41
 
Living Environment Regents June 2010 Question 23 PDF Print E-mail
Thursday, 26 May 2011 15:43
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Correct answer: (4) make inorganic materials available to plants

The organic material that makes up the living organisms in an ecosystem is eventually recycled, broken down and returned to the abiotic environment in forms that can be used by plants. Decomposers, which feed on nonliving organic material, are responsible for this recycling process. Bacteria and fungi are the most important decomposers in the environment because they secrete enzymes that digest organic materials and then absorb the breakdown products. Other decomposers, such as earthworms, crayfish, and cockroaches, digest organic materials. Then they breakdown the organic material and release inorganic products like carbon dioxide and ammonia. These will then be used by plants. Decomposers are also called heterotrophs.

Incorrect answers:

(1) produce food for plants by the process of photosynthesis

Plants do not need other organisms in order to get nutrition. Plants are known as producers or autotrophs, simply because they can produce their own food through photosynthesis, a process that uses light to synthesize sugars and other organic compounds to be used for cellular respiration and growth. On the other hand, those organisms that directly or indirectly depend on the photosynthetic output of producers are the decomposers or heterotrophs.

(2) provide energy for plants by the process of decay

Decomposers decay or breakdown organic materials to provide plants with inorganic compounds like carbon dioxide and ammonia, not energy.

(3) can rapidly produce and evolve

Decomposers do not have advantage on evolution compared to other members of the food web. Just like other organisms with different roles in the food web, they must follow the requirements for evolution. Not all decomposers can also reproduce faster than the others. For instance, fungi need suitable moist environment before they can multiply.
 
Living Environment Regents June 2010 Question 24 PDF Print E-mail
Thursday, 26 May 2011 15:45
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Correct answer: (2) Certain producer organisms would become more abundant in these areas.

Since manatees are herbivores, meaning they eat plants and algae, which are producers, then their extinction can cause an increase in the population of these producer organisms.

Incorrect answers:

(1) The biodiversity of these areas would not be affected.

One of the components of biodiversity is species richness or the number of species in a particular area. This means that the manatees' extinction can affect biodiversity.

(3) Other manatees would move into these area and restore the population.

Extinction means total loss of an organism in the whole ecosystem. Thus, once the manatees become extinct, there would be no other members of the species that can move, reproduce, and restore the population.

(4) Predators in these areas would occupy higher levels on the food pyramid.

The predators cannot move up the food pyramid because there would be a decrease in food that they could eat.
 
Living Environment Regents June 2010 Question 25 PDF Print E-mail
Thursday, 26 May 2011 15:47
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Correct answer: (1) habitat destruction

Biodiversity is the variety of life in an area, usually measured by the number of species that live in an area. Maintenance of the habitat, or the place where organisms live, is very important because when organisms do not have place to live in, their lives would be at risk. Among the choices given, habitat destruction is the most harmful because it does not bring about any benefit to biodiversity.

Incorrect answers:

(2) maintenance of food chains

Food chain is a simple model that shows how matter and energy move through an ecosystem. Thus, when there is favorable movement of matter and energy in an ecosystem, the biodiversity is in good order as well. A well-maintained food chain is not a threat to biodiversity.

(3) competition within a species

Competition is the natural behavior exhibited by organisms that fight for territory, resources, niche, etc. Competition maybe destructive or constructive to biodiversity. While it may obliterate the weakest of species, it increases the population of the strongest of species. Therefore, the best traits are passed on to the next generations, decreasing the chance of being endangered or extinct.

(4) a stable population size

Population refers to the group of organisms of the same species that interbreed and live in the same location in the same time frame. When the number or size of a population is stable, it means that the species is not at risk of becoming endangered or extinct, which helps diversity. Therefore, a stable population size is not a threat to biodiversity.

 
Living Environment Regents June 2010 Question 29 PDF Print E-mail
Thursday, 26 May 2011 15:54
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Correct answer: (4) hardwood forest stage

Ecological succession is defined as the orderly, natural changes and species replacements that occur in the communities of an ecosystem, which can take decades or even centuries. A bare area is first dominated by pioneer species like lichens and grass. When the pioneer species die, their decaying bodies cling to the bits of rock accumulation on cracks and crevices, initiating the first patches of soil. Over time, as the community of organisms changes and develops, additional habitats emerge, new species move in, and old species disappear. Eventually, the community becomes fairly stable and the area becomes a forest of hardwood trees inhabited by other forest-dwelling plants and animals. When there is little or no change in species composition, then the climax community has been reached. In the illustration the climax community is exhibited in the hardwood forest stage.

Incorrect answers:

(1) grass

The grass stage is not yet stable because there only few species that can thrive in the area and the species composition is still changing.

(2) shrub

The shrub provides only small canopy thus only covers a small area for habitat of other organisms.

(3) pine forest

During the pine forest stage, the area is dominated by pine trees which are characterized by thin leaves. Thus, there is no shade to allow survival of underbrush.

 
Living Environment Regents June 2010 Question 32 PDF Print E-mail
Thursday, 26 May 2011 16:07
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Correct answer: (3) Species B is better adapted to this environment.

A population is a group of organisms of the same species that interbreed and live in one location at the same time. When there is shortage in supply, members of the same population may compete with each other for food, water, and other resources. How organisms in a population share the resources of their environment determines how large the population becomes. In the diagram, species A exhibit decreasing number of individuals over time, meaning that there could be a shortage of resources and the population fails to adapt with this.

Incorrect answers:

(1) Species A is better adapted to this environment

If species A is better adapted to this environment, then the line representing the population must be going up. Therefore, this statement is false.

(2) Species A is a predator of species B.

A predator kills and eats another organism which results to the death of the prey. If the two populations have a predator-prey relationship, then the graph must show two almost parallel lines. Species A being the predator must increase in number along with the increase in number of species B.

(4) Species B is a parasite that has benefited species A Parasitism is a symbiotic relationship in which the symbiont (parasite) benefits at the expense of the host by living either within the host (endoparasite) or outside the host (ectoparasite). If the two populations exhibit parasitism and the number of species A (host) starts to decline, then the number of species B (parasite), which depends on its host must also decline.
 
Living Environment Regents June 2010 Question 35 PDF Print E-mail
Thursday, 26 May 2011 16:12
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Correct answer: (1) A

An energy pyramid is a graphical representation of the transfer of energy within the trophic levels in an ecosystem. The primary source of energy for living organisms is the sun. This solar energy is captured by the producers, represented by the bottom level of the pyramid. Examples of producers are plants and algae. Then these plants are eaten by primary consumers (level C) such as herbivores, and then converted into energy upon digestion. Then herbivores are consumed by secondary consumers (level B), which are carnivores that eat herbivores. The topmost level A contains the tertiary consumers, which are carnivores that eat other carnivores. Energy is transferred from level B to level A when tertiary consumers eat secondary consumers.

Incorrect answers:

(2) B

Energy cannot be transferred within the same level in the pyramid because they do not eat their same kind.

(3) C

Energy of organisms in level C comes from level D, which are the producers.

(4) D

Energy of organisms in level D comes from the sun through photosynthesis.
 
Living Environment Regents June 2010 Question 36 PDF Print E-mail
Thursday, 26 May 2011 16:14
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Correct answer: (4) D

Level D is composed of producers, which does not get energy from other organisms inside the pyramid. Producers such as plants and algae derive their energy from the sun and transforms in into chemical energy used up for body processes. This transformation of solar energy into chemical energy is called photosynthesis. Only producers are capable of doing this transformation.

Incorrect answers:

(1) A

Organisms in level A or tertiary producers get their energy from level B, by consuming organism in that level which are called secondary consumers.

(2) B

Organisms in level B consume those in level C (primary consumers) to get energy.

(3) C

Organisms in level C are called herbivores because they get their energy by eating plants and the like, which are located at the bottom of the pyramid.
 
Living Environment Regents June 2010 Question 39 PDF Print E-mail
Thursday, 26 May 2011 16:20
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Correct answer: (4) the organisms would probably survive because materials would cycle

Life depends on recycling of essential chemical elements. While an individual is alive, much of its chemical stock is routed continuously, as nutrients are absorbed and waste products released and this is called nutrient cycling. Atoms in the complex molecules of an organism at its time of death are returned as simple compounds to the atmosphere, soil or water by the action of decomposers such as microorganisms. This decomposition replaces the pools of inorganic nutrients that aquatic plants and other autotrophs used to build organic matter.

Incorrect answers:

(1) The water temperature would rapidly decrease.

This will not happen because the heat from the natural light would still help maintain the warm temperature of the water.

(2) The process of respiration in the snail would decrease

The snail undergoes aquatic respiration, or the process of obtaining oxygen from the water. Even if the aquarium is closed, oxygen is still present in the water in the form of dissolved oxygen, which comes from the aquatic plants inside the aquarium. Thus, the respiration of the snail would not decrease.

(3) The rate of reproduction of the fish would be affected.

There would be no reproduction even before the aquarium in covered because there is only one fish present in the aquarium.

 
Living Environment Regents June 2010 Question 41 PDF Print E-mail
Thursday, 26 May 2011 16:23
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Correct answer: (4) soil nutrients

Inorganic nutrients limit the productivity of several terrestrial ecosystems, like a field planted with corn. Plants need different nutrients, some in relatively large quantities and others only in trace amounts-but all are essential. Primary productivity depletes nutrients from a system, sometimes faster that they are replaced. If the field only has one kind of plant, productivity may slow down or stop because the specific nutrients used up by the crop is depleted. In most ecosystems, nitrogen or phosphorus is the key limiting nutrient. Thus, farmers practice multiple cropping systems to prevent depletion of nutrients. For instance, after a season of planting corn, they plant legumes which are capable of fixing nitrogen in the soil so that when they plant corn in the next season, the soil has enough nitrogen for primary productivity.

Incorrect answers:

(1) temperature

Corn has specific planting seasons depending on the climate of the country. For example, US growers plant corn during spring. Every spring, the temperature of the surrounding is quite similar, thus it does not limit the production of corn.

(2) sunlight

Sunlight is rarely a limiting factor in terrestrial ecosystems, especially is a corn field where each plant is exposed to almost similar amount of sunlight. However, in aquatic ecosystems, sunlight limits the productivity of phytoplankton communities. Productivity is generally greatest near the surface and declines sharply with depth, as light is rapidly absorbed by water and plankton.

(3) water

Water or precipitation could limit the productivity of plants. However, in a corn field where there is a system of irrigation, each plant receives fairly the same amount of water. Therefore, productivity is not limited by water supply.

Last Updated on Thursday, 26 May 2011 16:40
 
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