Energy and Ecosystems

Question 1

What is a producer?

Answer 1

A photosynthetic organism that manufactures organic substances using light energy

Question 2

What is a consumer?

Answer 2

An organism which obtains its energy by feeding on other organisms

Question 3

What is a primary consumer?

Answer 3

An organism which eats green plants

Question 4

What is a secondary consumer?

Answer 4

An organism which eats primary consumers

Question 5

What is a saprobiont?

Answer 5

A decomposed which breaks down complex material of dead organisms into simple ones to be reused

Question 6

Which organisms work as sapropbionts?

Answer 6

Fungi and bacteria

Question 7

What is a food chain?

Answer 7

A description of the relationship between producers and consumers

Question 8

What are the stages of a food chain called?

Answer 8

Trophic levels

Question 9

What is a food web?

Answer 9

The many chains within a habitat which are interlinked. Shows how an organism may eat or be eaten

Question 10

What is biomass?

Answer 10

Total mass of living material in a specific area at a given time

Question 11

Why is fresh biomass not a reliable amount?

Answer 11

Volume of water can vary

Question 12

What is the measurement of dry biomass?

Answer 12

Dry mass per given area per given time.

Question 13

How is biomass measured?

Answer 13

Sample is dried in an oven then weighed at regular intervals until the mass is constant

Question 14

How is the energy stored in biomass estimated?

Answer 14

Calorimeter

Question 15

How much energy from the sun is typically converted into organic matter?

Answer 15

1-3%

Question 16

Most of the suns energy is not converted to biomass, why?

Answer 16

• Light wrong wavelength
• Light misses the chlorophyll
• Factor other than light intensity limiting photosynthesis

Question 17

What is gross primary production?

Answer 17

Total amount of energy converted by plants in a given area at a given time

Question 18

What is net primary production?

Answer 18

NPP= GPP-R

Question 19

Why is consumption so insufficient?

Answer 19

Energy is lost as:
- Not all of the organism is consumed
- Lost as faeces
- Lost in excretionary materials
- Energy is lost during respiration as heat

Question 20

What is the net production in consumers?

Answer 20

N=i-(f+r)

Question 21

Why is the total mass of organisms in a particular place less at higher trophic levels?

Answer 21

Inefficiency of energy transfer between organisms. Less energy is available for those at higher trophic levels

Question 22

What is the efficiency of energy transfer?

Answer 22

Net production at a trophic level divided by the net production in the previous trophic level X 100

Question 23

What is productivity?

Answer 23

Amount of energy available to an organism

Question 24

Why do organisms require nitrogen?

Answer 24

For protein, nuclei acids

Question 25

In what form do plants absorb nitrogen?

Answer 25

Nitrate ions

Question 26

How are nitrate ions absorbed by plants?

Answer 26

Active transport into the roots

Question 27

How are nitrate replaced in the environment?

Answer 27

The break down of nitrogen containing compounds by decomposers

Question 28

How are nitrates replaced artificially?

Answer 28

Fertilisers

Question 29

What are the four stages of the nitrogen cycle?

Answer 29

- Ammonification - Nitrification - Nitrogen fixation - Denitrification

Question 30

What happens in ammonification?

Answer 30

Ammonia in the soil is converted to ammonium ions

Question 31

What happens in nitrification?

Answer 31

Bacteria oxidise ammonium ions into nitrite ions and a different bacteria creates nitrate ions

Question 32

What happens in nitrogen fixation?

Answer 32

Nitrogen gas is converted to nitrogen containing compounds by bacteria

Question 33

Where are the nitrogen fixing bacteria found?

Answer 33

Free living or mutualistic ( in the root nodules of plants)

Question 34

What do free living nitrogen fixing bacteria fo?

Answer 34

Reduce nitrogen gas to ammonia which are used to create amino acids released when they die

Question 35

What do mutualistic bacteria do?

Answer 35

Rescue nitrogen gas into ammonia which create amino acids given to plants so they receive carbohydrates in return

Question 36

What happens in denitrification?

Answer 36

Anaerobic denitrifying bacteria convert nitrates to nitrogen gas

Question 37

What are the benefits of ploughing?>

Answer 37

Increases air space, supports aerobic respiration of bacteria

Question 38

What biological molecules contain phosphorus?

Answer 38

ATP, Phospholipids, and nuclei acids

Question 39

How is phosphorus general found in nature?

Answer 39

As phosphate ions in sedimentary rock

Question 40

How are phosphates removed from rocks

Answer 40

Weathering and erosion

Question 41

How are phosphates incorporated into the food chain?>

Answer 41

Dissolved phosphates are absorbed into plants

Question 42

How do phosphate ions find their way into animas?

Answer 42

Some animals eat plants and so ingest the phosphate containing molecules

Question 43

How are phosphate ions released from animals?

Answer 43

Excretion

Question 44

How are phosphates removed from living organisms?

Answer 44

Upon death, decomposers break down the organism, releasing soluble phosphates which flow into bodies of water

Question 45

What are mycorrhizae?

Answer 45

Mutualistic fungi’s that live on the roots of plants. Help with the uptake of nitrogen and phosphates whilst receiving carbohydrates in return.

Question 46

How do mycorrhizae aid absorption of nutrients?

Answer 46

Act as extensions of the roots, increasing surface area for absorption. Also act as a sponge to hold nutrient rich water closer to the roots

Question 47

What are the two types of fertilisers?

Answer 47

Natural and artificial

Question 48

Why aren’t fertilisers required in nature?

Answer 48

Plants that remove the mineral ions return them when they are decomposed

Question 49

Why is it important to replenish the mineral ions in the soil?

Answer 49

They will become a limiting factor in photosynthesis if too low

Question 50

Why is it important that fertilisers are given in appropriate quantities?

Answer 50

There is a limit. Past a certain point they don’t add to the effectiveness

Question 51

How do fertilisers increase productivity?

Answer 51

Mineral ions readily available

Question 52

What are the effects of nitrogen containing fertilisers?

Answer 52

Increase area of leaves therefore increasing rate of photosynthesis and crop productivity

Question 53

What are the drawbacks of nitrogen containing fertilisers? `

Answer 53

Reduced species diversity, leaching and eutrophication

Question 54

Why does the use of nitrogen rich fertilisers affect species diversity?

Answer 54

Nitrogen rich soil favours fast growing species which outcompete other species

Question 55

What is leaching?

Answer 55

Process by which nutrients are washed out of the soil

Question 56

How are minerals leached from the soil?

Answer 56

Rainwater carries dissolved nutrients deep into the soil away from plant roots. This makes it into water ways and lakes

Question 57

Why is leaching dangerous to humans?

Answer 57

If the water source is a drinking source it has been linked to stomach cancer and insufficient oxygen transport in babies. Also causes eutrophication.

Question 58

What happens in eutrophication?

Answer 58

As the nitrate ion concentration increases due to leaching, it no longer is a limiting factor so plant and algae populations will grow. As algae is at the surface, it blocks light from lower depths so light is now a limiting factor. Saprobiontic bacteria population will grow as dead organic material ceases to be a limiting factor and this bacteria requires oxygen so the oxygen concentration decreases becoming a limiting factor for aerobic organisms.