4. Food Chains and Energy Pyramids Flashcards Preview

IB Biology SL > 4. Food Chains and Energy Pyramids > Flashcards

Flashcards in 4. Food Chains and Energy Pyramids Deck (13):
1

What does each species in a food chain feed on? Are there any exceptions?

- each species feeds on the previous one
- the exception is the producer, which makes its own food by photosynthesis

2

What is the trophic level of an organism?

its position in the food chain

3

Give some examples of trophic levels?

producer, primary consumer, tertiary consumer = different trophic levels

4

How many trophic levels does a food chain usually have?

- commonly: 3 or 4
- rarely: 5+

5

How can the limited length of food chains be explained?

by the theories of energy flow and energy loss:
- only a small proportion of biomass is passed from one trophic level to the next
- this proportion (expressed as %) is variable, but is unlikely to be more than 10%
- once the fourth/fifth trophic level is reached, too little energy remains to sustain another level

6

What do energy pyramids show?

how much energy flows through each trophic level in a community
- they clearly demonstrate the amount of energy dropped along food chains

7

How is energy shown in an energy pyramid?

amount of energy per square meter of area occupied by the community and per year (kJm^-2 year^-1)

8

What shape are energy pyramids? Are they always this shape? Why are they this shape?

- pyramid shaped
- yes
- because energy is lost at each trophic level, so less remains for the next level

9

Energy is lost at each successive stage of an energy pyramid. What is also lost? What does this mean?

biomass
- means that the energy content per gram of tissues of each successive tropic level is not lower

10

How is biomass lost?

- when carbon compounds are broken down by cell respiration and the carbon dioxide produced is excreted
- removal of waste products of metabolism such as urea

11

What type of graph is a pyramid of energy?

a bar chart with horizontal bars arrange symmetrically

12

How should you draw an pyramid of energy?

- bars drawn to scale and arrange symmetrically in horizontal position
- labels should indicate trophic level with producers at the base
- helpful to put energy values alongside each bar on pyramid

13

How can energy pyramids not be drawn?

as triangles - they do not show trophic levels accurately

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