TOPIC 5B - ENERGY TRANSFER AND NUTRIENT CYCLES

Question 1

What are producers?

Answer 1

Organisms that make their own food.

e.g. plants and algae produce their own food through photosynthesis

Question 2

What is biomass?

Answer 2

Biomass can also be thought of as the chemical energy stored in the plant.

Question 3

How is energy transferred in an ecosystem between organisms?

Answer 3

Enegery is transferred through the living organisms of an ecosystem when organisms eat other organisms.

e.g. producers are eaten by organisms called primary consumers. Primary consumers are then eaten by secondary consumers and secondary consumers are eaten by tertiary consumers. This is a food chain.

Question 4

How can you measure biomass of an organism?

Answer 4

(see page 120 in the revision guide)

Question 5

What is gross primary production (GPP)?

Answer 5

The total amount of chemical energy converted from light energy by plants, in a given area.

Question 6

When plants respire, what percentage of the GPP is lost to the environment?

Answer 6

50% GPP lost to environment

Question 7

What is the respiratory loss (R)?

Answer 7

When organisms lose GPP to the environment through respiration.

Question 8

What is the net primary production (NPP)?

Answer 8

NPP = GPP - R

The net primary production is the remaining chemical energy once some has been expired.

The NPP is the energy available to the plant for growth and reproduction - the energy is stored in the plants biomass. It is also the energy available to organisms at the next stage in the food chain.

Question 9

Read point 5) on the last topic on page 120 in the revision guide.

Answer 9

understand?

Question 10

Answer the example question on the bottom of page 120 in the revision guide.

Answer 10

correct?

Question 11

How do consumers get their energy?

Answer 11

Consumers get energy by ingesting plant material, or animals that have eaten plant material.

Question 12

Give 4 ways how chemical energy is lost before the nest trophic level?

Answer 12

Around 90% of the total energy is lost in various ways:

• Not all of the food is eaten
• Some are indigestible, egested as faeces (chemical energy lost to environment)
• Lost through respiration
• Lost through excretion of urine

Question 13

What is the consumers net production?

Give the formula for calculating it.

Answer 13

The energy that is left after all the chemical energy stored in the consumers’ biomass and is available to the next trophic level.

N = I - (F + R)

N = Net production
I =  Chemical energy in ingested food
F = Chemical energy lost in faeces
R = Energy lost through respiration

Question 14

Answer the 2 example questions in pink on page 121 in the revision guide.

Answer 14

correct?

Question 15

What is the difference between what food chains and food webs show?

Answer 15

Food chains show simple lines of energy transfer. Each other the stages in a food chain is called a trophic level.

Food webs show lots of food chains in an ecosystem and how they overlap.

(see page 122 in the revision guide for an example)

Question 16

What do decomposers do?

Answer 16

Decomposers break down dead or undigested material, allowing nutrients to be recycled.

Question 17

What 2 ways can farmers increase the efficiency of anergy transfer?

Answer 17

1. Simplifying food webs which rescues energy loss to other organisms. (get rid of pests)
   (see page 122 in the revision guide for more explanation)
2. Reducing respiratory losses which means energy is transferred more efficiently. (restricting movement and temperature)
   (see page 123 in the revision guide for more explanation)

Question 18

Explain why fungi and bacteria have an important role in the nutrient cycle?

Answer 18

(see page 124 in the revision guide)

Question 19

Draw the nitrogen cycle and explain each process.

Answer 19

(see page 124 in the revision guide)

Question 20

Draw the phosphorous cycle and explain each process.

Answer 20

(see page 124 in the revision guide)

Question 21

How are nutrients lost when crops are harvested?

How do farmers combat this?

Answer 21

(see page 125 in the revision guide)

Question 22

What environmental issues do fertilisers raise?

Answer 22

• Leaching
• Eutrophication
• Plants die

(see page 125 in the revision guide)

Question 23

Explain the 5 steps in eutrophication.

Answer 23

Eutrophication is caused by excess nutrients.

see page 126 in the revision guide

Question 24

What is leaching?

Answer 24

Leaching is when water-soluble compounds in the soil are washed away, e.g. by rain or irrigation systems. They’re often washed into nearby pongs and rivers.

This can lead to eutrophication.