Name: ______Date: ______

Unit 2A EcologyStudy Guide

  1. What is a biotic factor? Any living part of the environment
  2. Examples: Animals, plants, fungi, bacteria
  1. What is an abiotic factor? Any nonliving (physical) part of the environment
  2. Examples: Sunlight, heat, precipitation (rain/snow), humidity, water etc.
  1. Classify the following as biotic or abiotic or both:
  1. Rocks: Abiotic
  2. Pine trees: Biotic
  3. Waterfalls:Abiotic
  4. Clouds:Abiotic
  5. A mushroom in the soil:Both
  6. A fish swimming in a lake:Both
  1. What is a population?A Group of individuals of the same species living in the same area
  1. What is a community? Different populations living together in the same area
  1. Explain the difference between a population and a community? An example of a population would be a school of fish in the sea (the fish are all of the same species) a community would be the school of fish along with seals and sharks that are also living with in the same habitat
  1. What is an ecosystem? Give an example.All the organisms in a certain place together with their PHYSICAL environment
  1. Arrange the following in order from least broad (smallest) to most broad (largest):

Biome, biosphere, organism, community, population, ecosystem

ORGANISM  POPULATION COMMUNITY ECOSYSTEMBIOME BIOSPHERE

  1. On Earth, what supplies our energy? The sun
  1. Through what process does the sun enter an ecosystem? (hint:In this process, the plant uses sunlight to make sugar molecules.)Through the process of photosynthesis

Organisms obtain their food in different ways. Some organisms are producers, while others are consumers.

  1. What is a producer? Anorganism that uses energy from the sun to create its own food (sugars) through photosynthesis.
  2. Another term for producer: Autotroph
  3. Examples: Trees, grass, algae
  4. What is a consumer? Organisms that must consume other organisms as food.
  5. Another term for consumer:Heterotrophs
  6. Examples:Dogs, cows, fungi, bugs etc.
  7. What is a decomposer? Feed by chemically breaking down organic matter (dead organisms)
  8. Why are they so important to ecosystems? They help return organic materials back into the soil- if we didn’t have them then dead matter would just pile up.
  1. There are several different types of consumers in ecosystems: herbivores, carnivores, omnivores, decomposers, detritivores and scavengers. Fill in the following table describing how each type of consumer gets its food, and give some examples of each.

Type of consumer / Energy Source / Examples
Herbivore / Only eat plants / Deer, rabbits
Carnivore / Kill and eat other animals / Lions, cheetahs
Omnivore / Eat both plant and animal material / Bears, raccoon
Decomposer / Feed by chemically breaking down dead matter into detritus / Mushrooms, bacteria
Detritivore / Feed on detritus particles left over by the decomposers / Earthworms
Scavenger / Feed on dead organic matter / Vultures, hyenas
  1. What the difference between afood chain and a food web? Why is a food web a more accurate way than a food chain to depict energy transfer in an ecosystem?

Food chain- a series of steps in which organisms transfer chemical energy by eating and being eaten.

Food web- many food chains within an ecosystem

Food webs are more accurate because they depict ALL of the energy that is transferred through feeding within an ecosystem where as a food chain only illustrates the passing of energy through a specific number of organisms, not all.

  1. In an energy pyramid, which trophic level has the most energy available to it? What happens to the amount of energy available to the organisms as the trophic levels go up? How much? Explain why this happens.

The most energy is within the first trophic level which consists of primary producers.

As you travel up the pyramid the amount of energy decreases- only 10% of the available energy is passed up to the next trophic level because the other 90% is used by the organism to carry out biological process and some is lost in the form of heat.

  1. Draw an energy pyramid for a four step food chain.
  2. choose examples of a producerand each level of consumers
  3. Label each trophic level and the percentage of energy at each
  1. For the following food chain label the producer, herbivore, secondary consumer, tertiary consumer, and ALL carnivores.

Algae  flag fish  largemouth bass  bird  alligator

Producer Herbivore Secondary consumer Tertiary consumer

  1. What would happen to the population of largemouth bass if the population of alligators suddenly decreased a great deal?

If alligators decreased significantly, the population of largemouth bass would decrease since the population of birds would increase because they would not have as many predators (alligators) to eat them.

  1. The place where an organism lives is called its _____habitat______.
  1. What an organism does in its habitat, how it interacts with its environment, and how it contributes to an ecosystem is known as the organism’s ____niche______.
  1. Describe what happens if two different species try to occupy the same niche at the same time

According to the Competitive Exclusion Principle, two organisms cannot occupy the same niche, when this does occur there are 3 possible outcomes:

  1. One species will compete better for the niche and the other species will die out.
  2. One species will compete better for the niche and the other will move away.
  3. The two species will split or share the niche
  1. A keystone species is one that

A. eats a mixture of plants and animals.

B. is introduced into a community after a major disturbance.

C. causes the amount of diversity in a community to decrease.

D. helps to stabilize the populations of other species in the community.

Match the symbiotic relationship with the best description

a. parasitismb. mutualismc. commensalism

____B___24. Symbiotic relationship between two organisms where both benefit

____A___25. Symbiotic relationship between organisms where one benefits and one is harmed

____C___26. Symbiotic relationship between organisms where one benefits and the other is not

affected

27.Describe each of the following steps in the water cycle:

  • Evaporation- A process that helps introduces water into the atmosphere by changing its state of matter from a liquid to a gas.
  • Condensation- When water change’s from a gas to a liquid we usually see this in the form of clouds in the sky.
  • Precipitation- snow or rain- water is being released from the atmosphere on the land and water bodies.
  • Transpiration- The process by which water is carried throughout plants and them turns into vapor on their leaves.
  • Run off- Excess water that does not get absorbed by the ground that then “runs off” down hills and into rivers, streams, and oceans.
  • Ground water- water that is stored underground

28.For the following 3 steps in the carbon cycle, determine if the process increases or decreases the amount of CO2 and O2 in the environment.Use up ↑ and down ↓ arrows to indicate an increase or decrease.

Process / CO2 / O2
Cellular Respiration / ↑ / ↓
Photosynthesis / ↓ / ↑
Burning fossil fuels / ↑ / ↓

Choose if each statement describes photosynthesis or cellular respiration.

  1. photosynthesisb. cellular respiration

__A__29. Requires energy from the sun

__A__30. Converts CO2 from the atmosphere into food energy (glucose)

__B__31. Takes place in all organisms

___B_32. Converts glucose into ATP and releases CO2

Quick reminder – remember the equations for cellular respiration and photosynthesis!

Photosynthesis: 6CO2 + 6H20  C6H12O6 + 6O2

Cellular respiration: C6H12O6 + 6O2 6CO2 + 6H20 + ATP

33. The nitrogen cycle is driven by what unicellular organisms? Bacteria

34. ______is the process in which certain bacteria convert nitrogen gas into usable forms of nitrogen.

a. denitrificationb. nitrogen fixationc. decompostion

35. ______is the process by which some soil bacteria convert nitrates back into nitrogen gas.

a. nitrogen fixationb. denitrificationc. decomposition

36. Plants and animals can absorb nitrogen gas directly from the atmosphere.

a. trueb. false

37. What role do decomposers play in both the carbon and nitrogen cycles? Decomposers “recycle” dead matter by helping return it to the environment.

38. How do humans affect the nitrogen cycle?Through the application of excess fertilizers that then runoff into bodies of water.

1