Communities and ecosystems

Question 2

Define an ecosystem?

Answer 2

A community and the physical environment it interacts with.

Question 3

Define a community?

Answer 3

A group of populations living and interacting with each other in a common habitat.

Question 4

How can you describe respiration and photosynthesis?

Answer 4

Processes with inputs, outputs and transformations of energy and matter.

Question 5

What is respiration?

Answer 5

The conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy.

Question 6

Word equation for aerobic respiration?

Answer 6

Glucose + Oxygen to Carbon Dioxide and Water

Question 7

How do entropy levels change during respiration?

Answer 7

Energy is dissipated as heat, increasing the entropy in the ecosystem while the organism manages to maintain a relatively low entropy.

Question 8

Word equation for photosynthesis?

Answer 8

Carbon Dioxide + Water to Glucose + Oxygen

Question 9

What is a trophic level?

Answer 9

The position that an organism occupies in a food chain.

Question 10

What are producers?

Answer 10

They are autotrophs. They produce their own food using photosynthesis.

Question 11

Where are producers in a food chain?

Answer 11

They form the first trophic level.

Question 12

Do any producers not use photosynthesis?

Answer 12

Yes, chemosynthetic organisms can produce food without sunlight.

Question 13

What is bioaccumulation?

Answer 13

The build up of non-biodegradable pollutants within an organism or trophic level because they cannot be broken down.

Question 14

What is biomagnification?

Answer 14

The increase in concentration of non-biodegradable pollutants along a food chain.

Question 15

What is an example of biomagnification?

Answer 15

DDT and mercury.

Question 16

How do you determine if something is a living thing?

Answer 16

If it carries out the following processes: Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition

Question 17

What are the two types of respiration>?

Answer 17

Aerobic, anaerobic

Question 18

Chemical equation for aerobic respiration:

Answer 18

C6H12O6 + 6O2 to 6CO2 + 6H20 + energy

Question 19

What is the compensation point of a plant?

Answer 19

When all the carbon dioxide that a plant produces in respiration is used up in photosynthesis and there is no net release of carbon dioxide or oxygen (equilibrium).

Question 20

How is the biomass changing at the compensation point of a plant?

Answer 20

It’s not. The plant is neither adding biomass or using it.

Question 21

What is a food chain?

Answer 21

The flow of energy from one organism to the next.

Question 22

Name all stages of a food chain

Answer 22

Primary Producers Primary Consumers Secondary Consumers Tertiary Consumers Decomposers Detritivors

Question 23

How do decomposers obtain their energy?

What is an example of a decomposer?

Answer 23

From dead organisms by secreting extracellular enzymes that break down the organic matter.

E.g. a funghi

Question 24

How to detritivors obtain their energy?

What is the difference between detritivors and decomposers?

What is an example of a detritivor?

Answer 24

From decomposing organic material. i.e. feces or dead skin.

Decomposers are on a milliscopic level whereas detritivors are larger animals, such as a millipede.

Question 25

What is a food web?

Answer 25

A complex relationship of interrelated food chains.

Question 26

Example of a food chain:

Answer 26

In the African savannah: Acacias Impala Leopard Lion

Question 27

What are the positives of food chains in general?

Answer 27

They allow easy examination of energy transfers and losses. They give an idea of what feeds on what and what organisms can exist at the different trophic levels. They help to demonstrate that ecosystems are systems that are in balance,

Question 28

Where does the energy go in a food chain?

Answer 28

Most of it is lost as heat because of the second law of thermodynamics. More islost because herbivores destroy more plant material than they eat, by trampling on it or because they can’t eat it so they reject it. Some material is not digested and some dies and decomposes before eaten.

Question 29

What is the second law of thermodynamics?

Answer 29

It states that energy is degraded to a lower quality and finally to heat.