Energy and ecosystems summary
notes
19 May 2023 09:37
- Ultimate source of energy for almost all
organisms is sunlight - conserved as chemical
energy by plants
- Most plants use sunlight in making organic
compounds from carbon dioxide in the air or
water that surrounds them
- These organic compounds include sugars- used by
plants as respiratory substrates - remainder used
to make other groups of biological molecules
- Biological molecules form the biomass of plants-
means by which energy is passed between other
organisms
Three groups of organisms based on how they obtain
their energy and nutrients:
1. Producers- photosynthetic organisms that
manufacture organic substances using light
energy, water, carbon dioxide and mineral ions
2. Consumers- organisms that obtain energy by
feeding on other organisms rather than using
energy of sunlight directly. Those that directly eat
producers are called primary consumers. Those
eating primary consumers are called secondary
consumers. Those eating secondary consumers
are called tertiary consumers.
3. Saprobionts (decomposers)- groups of organisms
that break down the complex materials in dead
organisms into simple ones. Release valuable
minerals and elements in a form that can be
absorbed by plants- contribute to recycling.
Majority of this work is carried out by fungi and
bacteria. Feed by saprotrophic nutrition- secretes
enzymes out of its body- enzymes hydrolyse large
polymers in environment (ie polypeptides, lipids,
polysaccharides), produce small soluble
molecules that are reabsorbed by organism
notes
19 May 2023 09:37
- Ultimate source of energy for almost all
organisms is sunlight - conserved as chemical
energy by plants
- Most plants use sunlight in making organic
compounds from carbon dioxide in the air or
water that surrounds them
- These organic compounds include sugars- used by
plants as respiratory substrates - remainder used
to make other groups of biological molecules
- Biological molecules form the biomass of plants-
means by which energy is passed between other
organisms
Three groups of organisms based on how they obtain
their energy and nutrients:
1. Producers- photosynthetic organisms that
manufacture organic substances using light
energy, water, carbon dioxide and mineral ions
2. Consumers- organisms that obtain energy by
feeding on other organisms rather than using
energy of sunlight directly. Those that directly eat
producers are called primary consumers. Those
eating primary consumers are called secondary
consumers. Those eating secondary consumers
are called tertiary consumers.
3. Saprobionts (decomposers)- groups of organisms
that break down the complex materials in dead
organisms into simple ones. Release valuable
minerals and elements in a form that can be
absorbed by plants- contribute to recycling.
Majority of this work is carried out by fungi and
bacteria. Feed by saprotrophic nutrition- secretes
enzymes out of its body- enzymes hydrolyse large
polymers in environment (ie polypeptides, lipids,
polysaccharides), produce small soluble
molecules that are reabsorbed by organism
