Functioning of an Ecosystem

Question 1

Define ecosystem

Answer 1

The dynamic complex of plant, animal and microorganism communities and their non-living environment as a functional unit

Question 2

How do plants and animals interact within an ecostem?

Answer 2

Plants and animals are related to each other through relationships within food chains and food webs

Question 3

What are the two main types of ecosystem?

Answer 3

Terrestrial ecosystems or biomes (land-based ecosystems) e.g. forest, grasslands, deserts
Aquatic ecosystems (water-based ecosystems) e.g. ponds, lakes, rivers, oceans, coral reefs, estuaries and coastal and inland wetlands

Question 4

What needes to be present within an ecostem for it to be functioning functioning at its most productive level?

Answer 4

The natural processes which occur within ecosystems must be occurring as close as possible to their natural state. The most important processes of ecosystems are:
o Carbon Cycle
o Nitrogen and Phosphorous Cycle
o Nutrient Cycle
o Oxygen Cycle

Question 5

What are the most important processes of ecoststems? (4 cycles)

Answer 5

The most important processes of ecosystems are:
o Carbon Cycle
o Nitrogen and Phosphorous Cycle
o Nutrient Cycle
o Oxygen Cycle

Question 6

What is carbon?

Answer 6

Carbon is one of the most basic elements that make up all living things

Question 7

Outline how the carbon cycle works?

Answer 7

Carbon dioxide exists in the air
Plants use carbon dioxide to photosynthesize and make food
Animals eat plants and obtain carbon
Animals use carbon from plants for energy and growth
Animals produce waste and die
Decomposers feed on the dead matter and release carbon dioxide into the air as they respire

Question 8

Why do living things need nitrogen?

Answer 8

Living things need nitrogen for growth

Question 9

Outline the nitogen and phospherous cycle

Answer 9

The basic nitrogen cycle is quite simple:
o Green plants take in chemicals such as nitrogen and phosphorous from the soil.
o Plants use these chemicals to build proteins for growth.
o When plants die, decomposers break down the proteins into ammonium compounds
o Animals also eat the plants
o Animal waste and dead animal carcasses are broken down into ammonium compounds
o Bacteria in the soil can convert the ammonium back into nitrates.

Question 10

How can energy flows be examaned?

Answer 10

Energy flows can be examined by looking at the food chains and webs which exist within an ecosystem, and also examining the biomass structures within the ecosystem

Question 11

Outline the oxygen cycle

Answer 11

Oxygen exists in the air
Animals obtain oxygen by breathing
Plants produce oxygen and release it through their pores

Question 12

Define biomass

Answer 12

A measure of the mass of all organisms at a particular trophic level

Question 13

What does a biomass pryamid represnent?

Answer 13

A biomass pyramid shows the total weight (biomass) of organisms at each level for a particular habitat
Note - If the biomass pyramid exists in an ecosystem in this form than the ecosystem is in equilibrium

Question 14

Define food chain

Answer 14

Series of organisms, each eating or decomposing the preceding one

Question 15

Explain why a food web may be needed

Answer 15

In nature the feeding relationships of living things are much more complicated than simple food chains.
A sometimes complicated branching diagram which shows the feeding relationships of all living things in an ecosystem or particular area is called a food web

Question 16

How is energy transefered from on animal to another?

Answer 16

Energy is transferred from one animal to another through food chains and food webs

Question 17

What three roles make up the basic food chain?

Answer 17

Producer -> Consumer -> Decomposers

Question 18

Outline the basic food chain

Answer 18

Every food chain begins with a producer organism
Energy flows in the direction of the arrows
Some energy is lost at each step in the food chain as heat
The source of energy is the sun

Question 19

Define tropic levels

Answer 19

The feeding level of an organism is its trophic level

Question 20

A simplified ecosystem is made up of what three tropic levels?

Answer 20

Primary Trophic level – Producers (plants): autotrophic organisms, they convert sunlight into energy through photosynthesis

Secondary Trophic level – Consumers (most animals): organisms that are unable to produce their own food, and consume plants and animals to obtain energy

Tertiary Trophic level – Decomposers: organisms that feed by breaking down the dead organic matter in an ecosystem (e.g. fungi, bacteria)

Question 21

Outline the process of photosynthesis

Answer 21

Plants make food in their leaves, which contain a special green pigment, or colouring, called chlorophyll
The chlorophyll uses energy absorbed from sunlight to convert carbon dioxide from the air, and water from the ground, into a sugary form called glucose

Question 22

What is the science word formula for photosynthesis?

Answer 22

Sunlight + Carbon Dioxide + Water -> Glucose + Oxygen

Question 23

Define bioaccumulation

Answer 23

The gradual build up over time of a chemical in a living organism

Question 24

When does bioaccumulation occur? (2 reasons)

Answer 24

Occurs either because the chemical is taken up faster than it can be used, or because the chemical cannot be broken down for use by the organism (that is, the chemical cannot be metabolized)