What do food chains show?

Food chains show the transfer of energy from one organism to the next in an ecosystem.

Define the term trophic level .

The term trophic level refers to the position occupied by an organism in a food chain , e.g. the first trophic level is the organism at the bottom of the chain, followed by the second trophic level, etc.

What do food webs show?

Food webs show networks of interconnected food chains that show the interdependence between organisms in an ecosystem.

Define the term biomass .

The term biomass refers to the mass of living material present.

What do pyramids of biomass show?

Pyramid of biomass show the mass of living material present at each stage of a food chain.

How is energy transferred up food chains?

Energy is transferred up food chains when organisms consume the tissues of other organisms and convert it to biomass .

True or False? When a consumer eats a plant, all of the chemical energy stored in the plant is transferred to the biomass of the primary consumer.

False. While some of the chemical energy stored in the plant is transferred to the biomass of the consumer when it is eaten, much of it is transferred to the environment , e.g. as heat or in waste products.

How is energy transferred to less useful forms at each trophic level of a food chain, rather than being transferred into new biomass?

Energy is transferred to less useful forms, at each trophic level as follows: respiration generates heat which is released into the environment energy is transferred to metabolic waste which is excreted, e.g. urea in urine, water and carbon dioxide in respiration energy may remain within the tissues of the original organism, e.g. within parts that are not consumed, or within undigested material that is egested in faeces; this energy is transferred to decomposers

True or False? Energy is lost from food chains when organisms transfer energy to new biomass.

False. When energy is transferred to new biomass it is stored in the tissues ; this stored chemical energy is available to the next trophic level .

Why are food chains rarely made up of more than five trophic levels ?

Food chains are rarely made up of more than five trophic levels because of the energy losses at each trophic level; the total energy available eventually becomes too small to support another trophic level .

True or False? Pyramids of biomass are always pyramid-shaped due to energy losses between trophic levels.

True. Energy losses at each trophic level mean that each subsequent trophic level will contain less stored energy in the form of biomass .

How can the percentage efficiency of energy transfer in a food chain be calculated?

The percentage efficiency of energy transfer in a food chain can be calculated using the formula: efficiency = (energy transferred to biomass ÷ energy consumed) x 100

GCSEBiologyEdexcelFlashcards9. Ecosystems & Material CyclesFeeding Relationships

Feeding Relationships (Edexcel GCSE Biology)

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FrontTrophic Levels & Food Chains
What do food chains show?
FrontTrophic Levels & Food Chains
Construct a food chain that links together the following organisms:
oak tree
sparrow
caterpillar
BackTrophic Levels & Food Chains
A food chain that links the organisms oak tree, sparrow and caterpillar would be:
oak tree $\to$ caterpillar $\to$ sparrow

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What do food chains show?
Food chains show the transfer of energy from one organism to the next in an ecosystem.
Construct a food chain that links together the following organisms:
- oak tree
- sparrow
- caterpillar
A food chain that links the organisms oak tree, sparrow and caterpillar would be:
oak tree $\to$ caterpillar $\to$ sparrow
Define the term trophic level.
The term trophic level refers to the position occupied by an organism in a food chain, e.g. the first trophic level is the organism at the bottom of the chain, followed by the second trophic level, etc.
What do food webs show?
Food webs show networks of interconnected food chains that show the interdependence between organisms in an ecosystem.
Define the term biomass.
The term biomass refers to the mass of living material present.
What do pyramids of biomass show?
Pyramid of biomass show the mass of living material present at each stage of a food chain.
How is energy transferred up food chains?
Energy is transferred up food chains when organisms consume the tissues of other organisms and convert it to biomass.
True or False?
When a consumer eats a plant, all of the chemical energy stored in the plant is transferred to the biomass of the primary consumer.
False.
While some of the chemical energy stored in the plant is transferred to the biomass of the consumer when it is eaten, much of it is transferred to the environment, e.g. as heat or in waste products.
How is energy transferred to less useful forms at each trophic level of a food chain, rather than being transferred into new biomass?
Energy is transferred to less useful forms, at each trophic level as follows:
- respiration generates heat which is released into the environment
- energy is transferred to metabolic waste which is excreted, e.g. urea in urine, water and carbon dioxide in respiration
- energy may remain within the tissues of the original organism, e.g. within parts that are not consumed, or within undigested material that is egested in faeces; this energy is transferred to decomposers
True or False?
Energy is lost from food chains when organisms transfer energy to new biomass.
False.
When energy is transferred to new biomass it is stored in the tissues; this stored chemical energy is available to the next trophic level.
Why are food chains rarely made up of more than five trophic levels?
Food chains are rarely made up of more than five trophic levels because of the energy losses at each trophic level; the total energy available eventually becomes too small to support another trophic level.
True or False?
Pyramids of biomass are always pyramid-shaped due to energy losses between trophic levels.
True.
Energy losses at each trophic level mean that each subsequent trophic level will contain less stored energy in the form of biomass.
How can the percentage efficiency of energy transfer in a food chain be calculated?
The percentage efficiency of energy transfer in a food chain can be calculated using the formula:
efficiency = (energy transferred to biomass ÷ energy consumed) x 100

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