4.2 Energy Flow

Question 1

What is the supply of energy most ecosystem rely on?

define trophic level

Answer 1

sunlight

this is harvested by photosynthesis by producers

all other organisms and dependent on producers so indirectly rely on sunlight

this energy can only be accessed if producers are around (not sahara)

Question 2

how is the energy from the sun light harnessed?

Question 3

how does energy move in food chains?

Answer 3

up to 5 organisms as after this not enough energy is left at the top

the arrows in a food chain indicate direction of energy flow

Question 4

what is the role of respiration

Answer 4

• synthesizing large molecules e.g rna dna proteins
• pumping molecules / ions across membranes by active transport
• moving things (e.g. chromosomes) around cells

involves the break down of energy stores by oxidation (exothermic reactions) this is because the energy in glucose is not directly usable

some energy lost as heat

Question 5

what is biomass and how is impacted by tophic levels and food chains

Question 6

why is energy lost between tophic levels

Answer 6

1. released by respiration and lost as heat
2. organisms are not entirely consumed e.g. only eat some parts, some parts are indigestible, so goes to saphotrophs or detritivores
3. some material is egested in feces

only 10% of energy passed on

Question 7

different types of pyramids in ecology

Answer 7

units in pyramid of energy kJ m-2 yr-1

aquatic - kJm-3yr-1