4.2 Energy flow Flashcards
what do all ecosystems rely on?
supply of energy from sunlight
energy conversion
light energy is converted to chemical energy in carbon compounds by photosynthesis, to make carbohydrates, lipids and other carbon compounds in producers
food chain
a sequence of organisms, each of which feeds on the previous one.
living organisms need energy for cell activities such as
Synthesising large molecules like DNA, RNA and proteins.
Pumping molecules or ions across membranes by active transport.
Moving things around inside the cell, such as chromosomes or vesicles, or in muscle cells the protein fibres that cause muscle contraction.
living organisms can perform various energy conversions:
Light energy to chemical energy in photosynthesis.
Chemical energy to kinetic energy in muscle contraction.
Chemical energy to electrical energy in nerve cells.
Chemical energy to heat energy in heat-generating adipose tissue.
how is heat lost from ecosystems?
The heat may remain in the ecosystem for a while, but ultimately is lost, for example when heat is radiated into the atmosphere. Ecologists assume that all energy released by respiration for use in cell activities will ultimately be lost from an ecosystem.
why are the length of food chains short?
energy is lost between trophic levels
how is energy lost between trophic levels?
respiration as energy is released as heat
excretion food is unconsumed
pyramids of energy
represents the amount of energy converted to new biomass by each trophic level in an ecological community
