Efficiency Of Ecosystems- Topic 10

Question 1

Primary producer

Answer 1

Absorbs energy from the sun to synthesise organic molecules through photosynthesis

Question 2

Primary consumer

Answer 2

Organisms that consume producers and use the organic molecules to supply raw materials for their own processes

Question 3

Secondary consumer

Answer 3

Organisms that feed on primary consumers

Question 4

Tertiary consumer

Answer 4

Feed on secondary consumers. They are usually the top predators

Question 5

Decomposers

Answer 5

Final trophic level. Micro organisms that break down the remains of animals and plants returning mineral and nutrient to the soil

Question 6

Why is there not likely to be quaternary consumers?

Answer 6

Not enough energy left to support them

Question 7

What is the limitation of pyramid of numbers?

Answer 7

One producer could support multiple organisms

Question 8

What is biomass?

Answer 8

Organic molecules built from sunlight energy

Question 9

Limitations of a pyramid of biomass?

Answer 9

It’s more accurate to calculate dry mass but in order to do this you would have to oven an organism which is destructive to an ecosystem and ethically challenging.
Wet mass is usually measured and dry mass is estimated.

Different species may release different amounts of energy per unit mass

Question 10

Why are organism who eat more than one type of species more successful?

Answer 10

Because changes in the food chain will have less impact on them

Question 11

Name the 3 ways of representing trophic levels

Answer 11

Pyramid of number
Pyramid of biomass
Pyramid of energy

Question 12

Why is such a low percentage of solar energy that reaches the leaf converted into biomass? 5 reasons

Answer 12

1. Some light rays will not hit chloroplasts
2. Used to heat earths atmosphere
3. Used to evaporate water
4. Reflected by clouds and earths surface
5. Only some wavelengths of light can be used

Question 13

Why isn’t efficiency of energy transferred to each trophic level 100%? (Producer to primary)

Answer 13

Producer will use some to respite and some will be lost as heat
Leaves fall

Question 14

Why isn’t efficiency of energy transferred to each trophic level 100%? (Consumer)

Answer 14

Some of the plant is not eaten/ digested- eg cellulose
Lost in urine faeces heat and respiration
Next consumer will not digest whole organism (bones and hair)

Question 15

What is gross primary product?

Answer 15

The total solar energy that plants convert to organic matter (relates to producers)

Question 16

What is net primary production?

Answer 16

Amount of energy available to the next organism/ trophic level

Question 17

How do you calculate NPP?

Answer 17

GPP- respiratory loss

Unit= gm-2 year-1 for biomass or kjm-2 year-1 for energy

Question 18

What is trophic efficiency?

Answer 18

Efficiency of chemical potential energy transferred between trophic levels

Question 19

How do you measure trophic efficiency?

Answer 19

Energy available after transfer divided by energy available before transfer times 100

Question 20

Draw out the nitrogen cycle and the CO2 cycle

Answer 20

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Question 21

The nitrogen cycle: haber process

Answer 21

Production of fertiliser combining nitrogen and hydrogen

Question 22

The nitrogen cycle: nitrogen fixing

Answer 22

Atmospheric nitrogen into nitrogen containing compounds

Question 23

The nitrogen cycle: ammonification

Answer 23

The conversion of nitrogen containing organic compounds to ammonia. Carried out by decomposers

Question 24

The nitrogen cycle: denitrification

Answer 24

Conversion of soil nitrates into atmospheric nitrogen. By denitrifying bacteria

Question 25

The nitrogen cycle: Which bacteria fixes ammonia?

Answer 25

Rhizobium

Question 26

The nitrogen cycle: Which bacteria nitrifies ammonia into nitrites?

Answer 26

Nitrosomonas

Question 27

The nitrogen cycle: which bacteria nitrifies nitrites into nitrates

Answer 27

Nitrobacter

Question 28

Bombcalorimetry

Answer 28

• material burnt in oxygen
• temperature rise of water measured
• known volume of water
• chemical energy into heat energy
• convert temp into kJ

Question 29

How is CO2 from the atmosphere moved into the ocean?

Answer 29

• dissolves in water
• for carbon fixation
• by photosynthesis of phytoplankton

Question 30

What is the role of bacteria when adding CO2 back to the atmosphere?

Answer 30

• decomposition of organic matter
• bacteria produces enzymes for digestion
• respiration causes CO2 release

Question 31

Suggest why more carbon is entering the air than is leaving it?

Answer 31

• rate of production of CO2 is greater than rate of removal
• fossil fuels release CO2 when burnt
• this CO2 was locked up years ago in carbon sinks
• deforestation = less photosynthesis
• as water temp increases less CO2 is dissolved in the water therefore higher atmospheric CO2

Question 32

Why is there more CO2 at night?

Answer 32

No sunlight so photosynthesis stops