4.1 Species, communities and ecosystems

Question 1

Define the term species.

Answer 1

A group of organisms that can interbreed and produce fertile, viable offspring.

Question 2

Define the term population.

Answer 2

A group of organisms of the same species, living in the same area at the same time.

Question 3

Define the term community.

Answer 3

A group of different populations living together and interacting in a given area.

Question 4

Define the term habitat.

Answer 4

The environment in which a species lives / the normal location of an organism.

Question 5

Define the term ecosystem.

Answer 5

A community and it’s environment (including all biotic and abiotic factors).

Question 6

How do autotrophs obtain their organic molecules?

Answer 6

They synthesize organic molecules from inorganic nutrients within the environment, using energy from:
Light (photoautotrophs)
Oxidation reactions (chemoautotrophs)

Question 7

How do heterotrophs obtain their organic molecules?

Answer 7

From other organisms through a variety of feeding methods and food sources.

Question 8

What are the 3 types of heterotroph and what do they do?

Answer 8

Consumers - ingest other living organisms.
Detritivores - ingest detritus.
Saprotrophs - externally digest dead organisms

Question 9

What is another name for autotrophs?

Answer 9

Producers.

Question 10

What is the role of autotrophs in the nutrient cycle?

Answer 10

They convert inorganic nutrients into organic molecules.

Question 11

What is the role of heterotrophs in the nutrient cycle?

Answer 11

They ingest organic molecules and may release organic byproducts.

Question 12

What is the role of saprotrophs in the nutrient cycle?

Answer 12

They break down the nutrients in dead organisms and return them to the soil.

Question 13

What are three conditions sustainable ecosystems have?

Answer 13

Energy availability
Nutrient availability
Waste recycling

Question 14

Define the term mesocosm.

Answer 14

An enclosed environment with a controlled condition.

Question 15

Name two positive species associations.

Answer 15

Predator / prey relationships

Symbiotic interaction

Question 16

Name one negative species associations.

Answer 16

Competition.

Question 17

Through what sampling can the prescence of a species in a given area be determined?

Answer 17

Through quadrat sampling.

Question 18

Summarize the quadrat sampling process into 3 steps.

Answer 18

1. A rectangular/square frame is placed in an area, using random sampling.
2. The species numbers within the frame are counted.
3. The sampling process is repeated many times to gain a representative data set.

Question 19

Define positive association.

Answer 19

If two species are typically found within the same habitat.

Question 20

Define negative association.

Answer 20

If two species tend to not occur within the same habitat.

Question 21

What is quadrat sampling most effective for counting?

Answer 21

Plants and sessile animals.

Question 22

Name the 5 steps for creating a chi-squared test.

Answer 22

1. Identify hypotheses (null versus alternative)
2. Construct a table of frequencies (observed versus expected)
3. Apply the chi-squared formula
4. Determine the degree of freedom (df)
5. Identify the p value (should be <0.05)

Question 23

What do detritivores do? Name two examples as well.

Answer 23

They ingest non-living organic matter. Eg. earthworms and woodlice

Question 24

What do saprotrophs do? Name two examples as well.

Answer 24

They feed on non-living organic matter by secreting digestive enzymes and absorbing the products.

Question 25

Define photoautotroph.

Answer 25

An autotroph which makes organic compounds derived from the sun (solar energy)

Question 26

Define chemoautotroph.

Answer 26

An autotroph that makes organic compounds using energy derived from the oxidation of chemicals.