B16: Energy and Biomass in Food Chains and Natural Cycles Flashcards
What do green plants and algae use to absorb sun energy.
Chlorophyll
How does light energy add to a plant’s biomass?
Light energy - chemical energy in the bonds of glucose molecules that are made.
Pyramid of Biomass
A model of the mass of biological material in the organisms at each level of a food chain.
Reasons why the pyramid of biomass gets smaller.
> not all of an organism is eaten
biomass lost in faeces.
biomass lost in respiration.
Biomass
Biological material from living or recently living organisms.
Wet Biomass
Biomass with water
Dry Biomass
Biomass without water.
Why do carnivores have to eat less often than herbivores?
Meat is easier to digest than plants which herbivores can only eat part of (the rest is expelled as faeces), so carnivores have to eat less regularly.
How does movement use energy?
The muscles use energy to contract and get warm.
How is energy lost in maintaining a constant body temperature?
The body produces heat from the energy to maintain body temperature.
Why is eating meat less energy efficient than eating plants?
Because for every trophic level 90% of energy is lost.
Plant-animal-human=1%
Plant-human= 10%
Two ways to increase animal biomass faster.
> limiting movement so more energy goes towards producing larger biomass.
controlling the temperature of the room so no energy is lost through keeping warm.
What is the main source of energy for most communities of living organisms on earth?
Radiation from the sun.
Advantages of Battery Farming (chicken for meat and eggs)
> Lots of chickens are kept in a small space.
Little/no food waste.
Little energy wasted due to movement/heat loss.
Maximum weight gain/number of eggs laid.
Cheap eggs/chicken meat.
Disadvantages of Battery Farming (chicken for meat and eggs)
> Chickens are unable to behave naturally - may be debeaked and cannot perch.
Large Barns need heating and lighting.
Chicken legs may break as their bones are unable to car-
ry weight of rapidly growing bodies.
Risk of disease as so many birds are packed so closely
together.
Advantages of Free Range Chicken rearing
> Chickens live a more natural life.
There are no heating/lighting costs.
Less food needs to be supplied as the chickens can find it
themselves.
Farmers can charge more money for free-range eggs/
chickens.
Disadvantages of Free Range Chicken rearing
> Chickens are more vulnerable to weather and predators.
More land is needed per bird.
Eggs cannot be collected automatically so farmers have
to employ someone to fetch the eggs.
Fewer eggs are laid (especially in the winter when it is
cold and dark for longer periods of time).
Advantages of Intensive farming for beef
> Uses the male calves produced by dairy cows.
Weaning takes place for 8 weeks and then the farmer
knows exactly how much food each calf needs.
Balance of nutrients in food changes as the calf grows to
maximise its growth.
Kept indoors so that energy lost though movement and
heat loss can be kept to a minimum - calves can gain as
much as 1.5kg a day!
Cheap meat
Disadvantages of Intensive farming for beef
> Feed stuff must be bought and it can be expensive.
The cowsheds need care and cleaning.
The cowsheds need to be heated and lit.
Unnatural and Inhumane.
Advantages of free range cattle farming
> Calves are weaned naturally and they stay with their mothers for up to 6 months.
Feeding on grass or food which is grown by the farmer means that there is no contamination (eg. BSE).
Cattle can behave naturally and live a relatively natural life.
Disadvantages of free range cattle farming
> Animals may take slightly longer to gain weight as they are moving more actively - but they are less stressed.
More land is needed to provide grazing , hay and silage.
Why are fish stocks becoming so low?
Over fishing is depleting the numbers of breeding fish left in the sea.
Ways of controlling fish stocks
> Bigger house in fish nets to only catch larger fish.
Bans on fishing during the breeding season.
Strict quotas.
No fishing zones.
What is the problem with fishing quotas?
Throwing dead fish back into the sea does nothing to conserve the population.
