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Biology Revision Year 2 > Energy and Ecosystems > Flashcards

Flashcards in Energy and Ecosystems Deck (40)
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1

Define Population

all the organisms of one species in a habitat

2

Define community

all the different organisms of all species living in a habitat at a particular time

3

Define habitat

the place where an organism lives

4

Define niche

the role of a species in an ecosystem

5

Define trophic level

a stage of the food chain

6

What is productivity

the amount of energy transferred between trophic levels

7

What is gross primary production

The total amount of energy made by a producer KJm-2yr-2

8

What is respiratory loss

energy used in respiration

9

What is nett primary production

The amount of chemical energy the producer stores as biomass

10

How do we calculate net production?

N = I (R+F) where I is total energy ingested
R is respiratory loss, and F is energy lost via faeces/urine

11

Why is the efficiency of energy transfer between the sun and a plant very low? (approx. 2%)

- wrong WL of light
- light hits non photosynthetic region eg) bark
- light reflected
- lost as heat

12

Why is the efficiency of energy transfer between the plant and a consumer low? (approx. 10%)

- respiratory loss
- lost as heat
- not all plant is eaten
- some not digested

13

Why is the efficiency of energy transfer between the consumer and a secondary consumer low? (approx. 10 -15%)

- respiratory loss
- primary consumer uses energy for metabolism
- not all is eaten
- faeces
- lost as heat

14

Why might energy transfer be low?

- old animal - less energy into biomass
- herbivores - more faeces
- homiotherms/ endotherms (warm blooded)

15

How can farmers increase energy transfer efficiency within plant crops?

- reduce competition (herbicide/ insecticide)
- fertilisers - eg) nitrates

16

How can a farmer increase yield with animals?

- restrict movement - reduce respiratory loss
- keep warm
- slaughter the animal whilst it is still young
- control diet so a higher % of food is digested

17

what technique to increase yield can be applied to both animals and plants?

selective breeding

18

How can we measure an organisms dry biomass?

warm sample on a scale until mass remains constant (water has been removed)

19

when measuring biomass why is the temperature kept below 80 degrees Celsius?

to avoid combustion CO2 = biomass

20

Why do we use dry biomass to compare samples?

amount of water varies eg) cucumber and potato
dry biomass is more representative

21

What are the units for biomass?

Kgm-2

22

How else can we compare organisms?

mass of carbon

23

What are the units for mass of carbon?

kgm-2yr-1

24

Why don't we use mass of carbon as much as dry biomass?

hard to measure

25

How can we use calorimetry to estimate the energy stored in dried biomass?

burn substance completely
to heat a known volume of water
measure the temperature change and calculate the energy released

26

describe the 6 stages of the nitrogen cycle

1) Ammonium ions ---> nitr1tes by nitrification
2) nitrites -----> nitrate (late) by nitrification
3) denitrification in anaerobic conditions to nitrogen gas in atmosphere (unreactive)
4) nitrates to plants or nitrogen fixation of nitrogen in the atmosphere by leguminous plants
5) saprobiotic nutrition of animals and plants by decomposers
6) Ammonification of decomposer = back at 1

27

what are the 2 ways phosphate ions are returned to the soil in the phosphorous cycle?

weathering and erosion of rocks
saprobiotic nutrition

28

What is the role of microorganisms in the recycling of nutrients?

break down large organic compounds into small inorganic compounds (often soluble so they can be absorbed by plants)

29

What is a saprobiont?

digests food using extracellular enzymes by saprobiotic nutrition

30

Define Saprobiotic nutrition

digestion of organic matter by extracellular enzymes