Chapter 6: Ecosystems (Living World)

Question 1

What is an ecosystem?

Answer 1

A community of living organisms that interact with each other and with non living organisms.

Question 2

What are the feeding connections (what eats what) called?

Answer 2

Trophic relationships.

Question 3

What is a producer?

Answer 3

• An organism that takes inorganic matter (soil, water, minerals, sunlight, etc.) and uses it to make organic matter.
• Anything that does photosynthesis (plants).

Question 4

a) What are consumers?
b) What are the different levels of consumers?

Answer 4

a) An organism that feeds on other organisms.
b) 1st level (primary consumers), 2nd level (secondary consumers), 3rd level (tertiary consumers).

Question 5

What are decomposers?

Answer 5

• An organism that takes organic matter and transforms it into inorganic matter (ex: nutrients).
• Bacteria and fungus are examples of decomposers.

Question 6

What is a food web?

Answer 6

A diagram used to represent the trophic relationships in an ecosystem.
ARROWS SHOW THE DIRECTION OF THE TRANSFER OF CHEMICAL ENERGY - FROM PREY TO PREDATOR.

Question 7

What is a disturbance and what are its consequences?

Answer 7

An event that affects an ecosystem (usually negative).
Consequences:
- Death of some organisms
- Change in availability of food ressouces

Question 8

How can we classify disturbances?

Answer 8

a) Natural
b) Human
c) Human or Natural

Question 9

What is a contaminant?

Answer 9

A substance that disturbs an ecosystem.

Question 10

What is bioaccumulation?

Answer 10

• The accumulation of a contaminant in the tissues of an organism (only one!) over time.
• It can contaminant an organism through its food source and through physical contact.

Question 11

What is bioconcentration?

Answer 11

Bioconcentration is a form of bioaccumulation, but the contamination only occurs due to physical contact.

Question 12

What is biomagnification?

Answer 12

Biomagnification is when organisms at the top of the food chain have a higher concentration of a contaminant.

Question 13

What factors affect toxicity?

Answer 13

1) Nature of the Contaminant
2) Concentration
3) Duration of the Contact

Question 14

What is toxicity threshold?

Answer 14

The concentration of a contaminant in the tissues of an organism above which significant, problamatic harmful effects are observed (expressed in mg/kg).
Ex: reduced mobility, reproductive issues, etc.

Question 15

What is lethal dose 50?

Answer 15

The dose of a toxin (in mg/kg) that will result in the death of 50% of the population.
USE DIMENSIONAL ANALYSIS TO SOLVE.