Energy Transfers Flashcards
What is energy
A property of matter and or radiation that allows work to be done
What are producers
At the start of food chains
They are auto autotrophic so tgey build up organic compounds from simple molecules needed for growth
Usually photosynthetic
What are primary consumers
Consume producers (eat them) because they are hetrotrophic so rely on external sources of organic compound
What is a secondary consumer
A heliotrope that eats primary consumers
What is a saprobiont
A decomposer thar breaks down complex organic compounds in dead organisms
Release extra-cellular enzymes that hydrolyse material so it can be absorbed across their cell membrane
Examples are bacteria and fungi
What is a food web
Many food chains in a particular habitat that can be linked together to show energy flow in a feeding relationship of a habitat
What is a food chain
A chain of the flow of energy in a feeding relationship usually 4 or 4 tropic levels
What do the arrows represent in a food chain
The direction of energy being transfered when an animal or plant is eaten (consumed)
What is a tropic level
One level in the feeding relationship between different groups of a food chain
What is biomass
The total mass of organic material (carbon) at a specific area at a given time
Features of wet/fresh biomass
Living
Easy to assess
Variable water content so unreliable
Variable food indigested so unreliable
Features of dry biomass
Dead
Hard to assess
Non variable water content so reliable
Unreliable and unrepresentative since samples must be small because large samples are unethical
How do you make wet biomass dry
Heat at hot temperatures (e.g 100°C)
Keep until egested non-digestable food and direct then flush out their opened gut
How can a bomb calorimeter be used to find biomass
Allows chemical energy stored in biomass to be estimated
Sample of dry biomass is combusted in a sealed container
Chamber is surrounded by a water bath and the heat energy released causes a temperature increase in water
Using the specific heat capacity and volume of water with the rise in temperature, the energy released can be calculated
Why is a pyramid of energy shaped the way it is
Energy is lost at each level
Explain the energy losses from sun to producer
Some light reflected
Some light absorbed by water vapour in atmosphere
Some light is the wrong wavelength
Some light doesn’t strike chlorophyll
Only 1-3% of available light energy trapped and used
What is GPP
Gross Primary Production
Rate of photosynthesis
What is NPP
Net Primary Production
This is passed on to the next trophic level (the energy stored as biomass)
Explain energy losses from producer to primary consumer
Large amounts are indigestible and lost as faeces
Not all parts can be eaten e.g roots, bones, bark
Some energy lost in excretion e.g urea
Some energy lost via respiration as heat to the environment
Why are there 4 or 5 max trophic levels in a food chain
Energy transfer is inefficient and results in large losses at each trophic level
So usually not enough energy to support a breeding population at a higher trophic level
Equation for net production of a producer
NPP=GPP-R
Where R is respiratory losses
Biomass is also lost as CO2 in respiration
Equation for net product production of a consumer
N=I-(F+R)
N= Net production I= Chemical energy store in indigested food F= Energy lost in faeces R= Energy lost via respiration
Suitable units for efficiency of Energy transfer
Land:KJm-²year-¹
Aquatic:KJm-³year-¹
Advantage of dry not fresh biomass
Water content variable in fresh but this will not affect dry mass
How can energy conversion rate be increased
Restricting movement = less respiratory loss due to less muscle contraction
Keeping indoors and heating = reduce heat loss from body
Using more nutritious food = increased growth
Food easy to absorb = less energy lost in egestion
Selective breading = some breeds more efficient at transfer of energy into biomass
Slaughtered before adulthood = more energy transfer to biomass
Monoculture
Growing one particular crop over very large areas
Issue with monocultures
Easy for disease to spread
Easy for insects to travel from plant to plant
Very large area can be affected in a very short space of time
Really decrease biodiversity through loss of niches
Types of pesticides
Insecticides
Herbicides
Fungicides
Pesticides
Kill a local population of pests at a particular time
