Energy And Ecosystems

Question 1

What do you call organisms that photosynthesise

Answer 1

Producer, autotroph

Question 2

What are consumers and heterotrophs

Answer 2

Organisms that obtain energy by feeding on other organisms

Question 3

What are the diagrammatic representations showing feeding relationships between organisms and direction of energy flow

Answer 3

Food chain, food web

Question 4

What is the trophic level

Answer 4

The stage in the food chain where an organism feeds

Question 5

What are the organisms that break down dead material, releasing minerals

Answer 5

Decomposer and saprobiont

Question 6

What are animals that eat plants

Answer 6

Herbivore, primary consumers

Question 7

What are animals that eat animals

Answer 7

Carnivore, secondary consumer, tertiary consumer

Question 8

What is an animal that eats plants and animals

Answer 8

Omnivore

Question 9

Define biomass

Answer 9

The mass of carbon or dry mass of tissue in a given area at a given time

Question 10

What are the units for measuring biomass

Answer 10

g m -2 or g m -3 (in water)

Question 11

What are two ways to measure biomass

Answer 11

1. Burn food mounted on a needle under a tube with water and thermometer (measure temp change) 2. Use a calorimeter (put dried sample in chamber, wires set it alight, there is stirrer and 02 supply to water and temp change is measured)

Question 12

What are the problems with measuring biomass

Answer 12

The sample has to be dead as fresh mass contains water which isn’t organic and doesn’t represent stored chemical energy, water is also variable

Question 13

Definition of gross primary production

Answer 13

The total quantity of energy stored as plant biomass in a given area or volume in a given time

Question 14

Net primary production definition

Answer 14

The chemical energy store left after taking respiration into account

Question 15

How to work out NPP

Answer 15

NPP=GPP- R (photosynthesis take respiration)

Question 16

What are the common features of all nutrient cycles

Answer 16

Inorganic nutrients are taken up by producers, producers convert nutrients into bio mols, organic bio mols pass through food chains to consumers, org mols in consumers waste and dead organisms are consumed and broken down by saprobionts that release nutrients back into environment in inorganic form

Question 17

What is nitrogen used in biological molecules

Answer 17

Amino acids, DNA, ATP, RNA, NAD, proteins

Question 18

What is phosphate used for in bio mols

Answer 18

Phospholipids, ATP, DNA, RNA, NADP

Question 19

Explain the features of the phosphorus cycle

Answer 19

Inorganic phosphate ions in soil and water are absorbed by active transport by producers. The organic biomass is then passed to consumers by feeding. Biomass from consumers in death and waste is consumed by saprobionts and decomposed back into inorganic phosphate. Also rock cycle where deposition of saprobionts into rocks occurs then erosion into phosphate ions

Question 20

Describe the features of the nitrogen cycle

Answer 20

Some organisms covert atmospheric nitrogen into ammonia (to produce proteins for growth)during nitrogen fixation for producers. Biomass passed to primary consumers through feeding and also passed to secondary consumers through feeding. Death and waste (PROTEINS/AA broken down) from producers and consumers are consumed by saprobionts which release ammonium ions into soil and water in ammonification. Ammonium oxidised to nitrite ions by nitrifying bacteria (nitrification). Further oxidation by same bacteria forms nitrate ions which are absorbed by ROOTS IN producers or converted to atmospheric N by denitrification

Question 21

What is mycorrhizae

Answer 21

Associations between fungi and plant roots where fungi act as extensions of plant root system ( increasing SA) mycorrhizae hold water and minerals around root and enhance mineral ion uptake in return for sugars

Question 22

How do fertilisers increase productivity

Answer 22

Plants require minerals for growth, Nitrogen used for amino acids & protein synthesis, the bases in nucleotides (ATP,DNA,RNA) ATP. phosphate used for phospholipids and nucleotides. Early growth increases the leaf area so plants can photosynthesise more efficiently Leading to greater productivity.

Question 23

The difference between natural and artificial fertilisers

Answer 23

Natural: organic, made of decaying plants and animals and animal wastes artificial: inorganic, mined from rocks, chemically synthesised

Question 24

Why are fertilisers needed in agricultural ecosystems

Answer 24

They increase the growth rate of crops, minerals can be a limiting factor of growth. Increase yield means increased profit and more efficient food production. When crops harvested, minerals are removed from ecosystem, leaving soil depleted

Question 25

What are the main environmental effects of nitrogen containing fertilisers

Answer 25

N rich soils favour growth of grasses and many plant species are out competed so biodiversity is reduced. Leaching and run off pollutes water and causes eutrophication

Question 26

What is leaching

Answer 26

Nitrates in fertilisers very soluble and are easily removed by the soil and run into rivers and lakes

Question 27

What is the process of eutrophication

Answer 27

1. Leaching increases nitrate concs so it’s no longer a limiting factor for growth of plants and algae 2. Algae grows rapidly at surface and upper layer of water becomes densely populated W plants (algal bloom) 3. Dense surface layer absorbs all light and stops light penetrating to lower depths. 4. Light becomes limiting factor for algae at lower depths and many die 5. Increase in dead plants stimulates growth of saprobiontic bacteria as their food supply no longer limiting factor 6. As they consume dead algae they respire and consume 02 7. Conc of 02 in water falls and ammonia and nitrates are released 8 anaerobic orgs flourish without competition and further decompose dead materials releasing more ammonia and nitrates and hydrogen sulphide, making water putrid / plants unable to photosynthesise so no 02 for fish

Question 28

What is a process other than ammonification and nitrogen fixation carried out by microorganisms which adds ammonium ions to soil

Answer 28

Protein and amino acids are broken down into ammonia/ammonium ions by saprobionts

Question 29

How could you determine the dry mass of a sample of plant material

Answer 29

Heat at 100c/evaporate water, then weight and heat until no further mass change

Question 30

What are ways crop rotation can lead to high crop yields

Answer 30

Grow crops with nitrogen fixing bacteria (legumes) such as clover. Different crops use different minerals/ions from the soil, different crops also have different pathogens and diseases

Question 31

Why is farming cattle for humans to eat less efficient than farming crops because of energy transfer?

Answer 31

Energy is lost between/at tropic levels. Energy is also lost via respiration, excretion, faeces