Ch13 Energy and ecosystems

Question 1

Producer

Answer 1

photosynthetic organisms that manufacture organic substances

Question 2

Consumer

Answer 2

organisms that obtain energy by consuming other organisms

don’t produce their own food by photosynthesis

Question 3

Saprobionts

Answer 3

group of organisms that break complex materials in dead organisms into simple ones

release valuable minerals and elements in form absorbable by plants

Question 4

Food chain

Answer 4

feeding relationship with trophic levels
arrows represent direction of energy flow

Question 5

Biomass

Answer 5

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

Question 6

Calculating biomass

Answer 6

1. presence of varying water amounts makes it unreliable
2. dry mass is often small sample which may not be representative
3. grams/square metre

Question 7

Bomb calorimetry

Answer 7

1. sample of dry mass is weighed
2. burnt in pure O2 in sealed chamber(bomb)
3. bomb put in water bath
4. heat of combustion causes temperature rise in water
5. calculate energy released from mass

Question 8

Why sun’s energy not converted to organic matter

Answer 8

1. over 90% absorbed by atmosphere or reflected by clouds or dust
2. not all light wavelengths can be absorbed
3. light may not fall on chlorophyll
4. limiting factor affects rate of photosynthesis

Question 9

Gross primary production

Answer 9

total quantity of chemical energy store in plant biomass in given area

Question 10

Net primary production

Answer 10

GPP - respiratory losses

I- (F+R)
Chemical energy storage of ingested food - energy lost in (faeces and urine + respiration)

Question 11

Low % of energy transferred in food chain

Answer 11

1. some of organism not consumed
2. some parts unable to be digested
3. lost in excretory materials
4. lost in heat from respiration

Question 12

Percentage efficiency

Answer 12

energy available after transfer / energy available before transfer

kjm^-2year^-1

Question 13

Farming practices increase productivity

Answer 13

1. fertilisers
2. nitrogen for proteins or phosphorous for ATP
3. selective breeding
4. ploughing- aeration for nitrification
5. crop rotation for pest reduction