Energy Transfers - B13 Flashcards
Define producer
Photosynthetic organisms that make organic substances using light energy, water, CO2 and minerals
Define consumer
Any organisms which feeds to gain it’s energy(primary/ secondary/tertiary)
Define saprobiont
Digest dead organisms into simple molecules
Define food chain
Describes a relationship where the producer is eaten by the primary consumer which is then eaten by the secondary consumer etc. Each stage in the chain is known as a trophic level
What is a food web
Shows how all the food chains within a single habitat/ecosystem link together
What is the definition of biomass?
The mass of living material
=chemical energy(stored in a plant)
What compounds make up the biomass?
Producers synthesise biological compounds during photosynthesis
How is energy transferred through an ecosystem?
When organisms are eaten
What is biomes measured as?
Biomass can be measured in terms of the mass of carbon that an organism contains or the dry mass(water removed) of its fissure per unit area per time
How is biomass measured?
-to measure dry mass, sample organism is dried in an oven at a low temperature
-weigh regularly and when weight becomes constant, all the water has been removed
-generally half the dry weight is the mass of carbon
What is dry mass measured in?
kgm^-2
Why do we use dry mass?
Dry mass is used to measure biomass because dry mass measures biological material as the water content varies between organisms.
-dry mass is a measure of production of organic material
-a way of measuring growth other than length
-water content of seedlings varies
What is calorimeter used for?
-Used to estimate the amount of chemical energy stored in the biomass by burning the biomass in a calorimeter
-the amount of heat given off is how much energy is stored measured in Joules(J)
What is gross primary production(GPP)?
The total amount of chemical energy, converted from light energy by a plant, in a given area, in a given time.
It is a fixed value.
What is respiratory loss?
Approximately 50% of GPP is lost to the environment as heat when plants respire.
The remaining chemical energy is called the net primary production(NPP).
What is the Net Primary Production(NPP)?
The energy available to plants Rory growth and reproduction, also energy available to next organisms in food chain.
What is the equation for net primary production?
NPP= GPP-R
As the R is lower, NPP is higher, increasing biomass, so the plant can grow more.
What are the ways in which energy can be lost in net production in consumers?
-some of the organisms isn’t consumed
-some of the material consumed couldn’t be digested, so it’s egested
-energy is lost the the environment as heat through respiration
-biomass is lost through excretion of molecules
What is the equation for net production of consumers?
N=I-(F+R)
N is the net production
I is the chemical energy in ingested food
F is the chemical energy lost in faeces and urine
R is the energy lost through respiration
Why does energy transfer become more efficient as you move up the food chain?
-from producer to consumer 5-10%
-from consumer to consumer 10-20%
-because plants contain more indigestible matter than animals
What is the equation for % efficiency of energy transfer?
% efficiency if energy transfer= net production of trophic level/net production of previous trophic level x 100
True or false:the amount of energy available is less at each level is less as you move up a food chain.
True
Why is most light not used in photosynthesis?
-light is reflected
-it is the wrong wavelength
-misses the chlorophyll/chloroplast
-CO2 and/or temperature are limiting factors
How do farming practices try to increase the amount of energy available for human consumption?
-reduce the energy lost to other organisms
-reduce the energy lost through respiration of livestock
How are pests used to simplify food webs?
-pests reduce the amount of energy available for crop growth-reduces the NPP
-by simplifying food webs, it will increase the amount of energy available for humans
-by getting rid of food chains that dint include humans, NPP of the crop increases as less energy is lost
How is respiratory loss reduced in farming?
-fanciers increase the NO of their livestock by controlling the conditions they live in
-they aim to reduce energy loss by body heat by keeping areas warm where animals are kept
-reducing the movement of animals reduced the amount of energy used from respiration
-both of these causes increased biomass - more chemical energy stored- more efficient energy transfer to humans
What is an advantage and an ethical issue with reducing respiratory loss in farming?
+ : more food can be produced in shorter amount of time and at a lower cost
- : intensively bred animals can cause pain and distress to animals and restricts some of their natural behaviours
What are some methods used to improve productivity of crops?
-add fertiliser - providing more NPK
-NPK used to make organic substances such as DNA, proteins etc.
-selectively breed crops
-plough the soil - aerates so nitrification can still occur(aerobic process) and denitrification doesn’t occur( anaerobic process)
-use of chemical/ biological pesticides- improves NPP
-use of herbicides - reduces competition for resources
-crop rotation- different crops require different amount of nutrients(leguminous plants have nitrogen fixing bacteria in roots)
