Energy Transfers Flashcards
1
Q
Chemical energy
A
- absorbed by chlorophyll in the form of light
- stored along with other organic compound
- produces food (mostly sugars) for the plant
- used for respiration, enabling survival
2
Q
Biomass
A
- total mass of living material in a specific area at a given time
- firmed by sugars (glucose -> cellulose) by respiration
- allows energy to be passed between organisms
- hard to calculate due to varying water content
3
Q
Producers
A
- photosynthetic
* manufacture organic substances using light energy, water, CO2 and mineral ions
4
Q
Saprobionts
A
- decomposers
- break down complex materials in dead organisms into simpler ones
- release minerals and elements back into the soil (recycling)
- allow plant survival
5
Q
Food chains
A
- v simple
- arrows represent flow of energy
- trophic levels
6
Q
Food webs
A
- more complex
* animals consume more than one type of organism
7
Q
Calculating biomass
A
- measure dry mass/mass of carbon
- organism must be dead -> small sample is not representative
- units -> pay attention to whether area or volume is being measured (g/(scale factor))
8
Q
Calorimètry
A
- uses a bomb calorimeter
- used to estimate chemical energy store in dry mass
- thermometer, stirrer, water, O2, sample, vessel
- dry material weighed and then burnt in pure O2
- can do exo/endo reactions
- vacuum-sealed; no heat lost; accurate
- need to know volume of water bath
- record ΔT with thermometer
- calculate thermal energy transfer
- Q = mcΔT
9
Q
Light energy absorbed by producers
A
- 1%
- wavelengths reflected by clouds/atmosphere/particulates
- fall on leaf but not on chlorophyll
- not all wavelengths absorbed
10
Q
Gross primary production
A
- total quantity of the chemical energy store in plant biomass in a given area/volume in a given time
- 20-50% used in respiration
11
Q
Net primary production
A
- chemical energy store left after respiration
- available for growth, reproduction, and consumption by other trophic levels
- 10% used by primary consumers for growth
- 20% used by 2° and 3° consumers (slightly more efficient)
- NPP = GPP - R
12
Q
Why is the transfer so low?
A
- some of the organism is not consumed
- some parts are not digested - lost in fæces
- some energy is lost in excretory materials (e.g. urine)
- energy lost as heat during respiration or movement
13
Q
Energy lost during respiration
A
Higher in mammals and birds; lots of energy needed to maintain comparatively high body temperature; heat is constantly lost to environment
14
Q
Energy available to consumers
A
- calculate net product of consumers > total chemical energy store after losses to fæces, urine and respiration from ingested plant food
- N = I - (F + R)
15
Q
Impact of inefficient energy exchange
A
- most food chains only have 4/5 trophic levels
- insufficient energy is available I support a large enough breeding population at higher trophic levels
- biomass is lower at higher trophic levels
- total energy available is lower at each trophic level
