The living world

Question 1

Using a small scale UK ecosystem of a freshwater pond, illustrate the concepts of its interrelations using terms such as producers, decomposers, primary/secondary/tertiary consumers, food chain, food web and nutrients cycling:

Answer 1

In a freshwater pond, producers such as pondweed plants absorb the sun’s energy to photosynthesis glucose to convert into proteins. herbivores such as worms feed on the producers as primary consumers, which are then preyed on by secondary consumers such as a grass snake which is then eaten by bigger tertiary predators such as herons. These links between animals make up a food chain which is then intercepted by other animals that are interdependent, creating a food web. when these organisms die, they decompose where decomposers digest the dead matter and recycle its nutrients back into the environment for producers to then use to grow more.

Question 2

What are producers?

Answer 2

A producer is an organism that absorbs energy from the environment (sunlight) to convert nutrients into glucose (food) via photosynthesis.

Question 3

What are consumers?

Answer 3

an organisms that gets its energy from eating other animals or plants.

Question 4

What are decomposers?

Answer 4

an organism that digests dead matter, converting its mass into nutrients to be released back into the environment to source producers with energy.

Question 5

What is nutrient cycling?

Answer 5

When the nutrients from a dead biomass is retuned to the environment by a decomposer to feed energy back into the food web.

Question 6

What is the difference between a food web and food chain?

Answer 6

a food chain is the single relations between a consumer and producer that forms a line, whereas a food web is the hierarchy between multiple interlinked animals.

Question 7

State natural factors that can change an ecosystem:

Answer 7

-droughts
-floods
-wildfires
-extreme temperatures

Question 8

State human factors that can change an ecosystem:

Answer 8

-agricultural fertilisers
-introduction of foreign species
-mowing the lawn
-draining ponds
-deforestation
-urbanisation

Question 9

State the change and give reasons to why biomass changes with each level of a food chain:

Answer 9

As you progress up a food chain, the biomass decreases this is because:

• energy is lost through respiration/ excretion/ movement/ digestion.
• not all of the organism is consumed.

Question 10

Summarise the location and characteristics of tropical rainforests:

Answer 10

Around the equator.
High temperatures and high precipitation due to low pressure which allows vegetation to grow.

Question 11

Summarise the location and characteristics of deserts

Answer 11

Roughly 30º north and south of the equator.
High temperatures and little rainfall due to being in high pressure belts. High pressure means no clouds form, resulting in very high temps in the day and very low temps at night. Few organisms and plants live there due to lack of water.

Question 12

Summarise the location and characteristics of polar regions.

Answer 12

Arctic / Antarctic areas (extreme poles of high pressure).
low temperatures and little rainfall.

Question 13

Summarise the location and characteristics of tundras:

Answer 13

From the Arctic circle to about 60-70º north.
Low growing plants to cope with the low temperatures and high windspeed. Geology rich in natural oil and prone to economic human exploitation.