Summary Unit 7- genetics, populations, ecosystems, the control of gene expression

Ecosystem
s
Ecosystem Biomass
 All the living organisms that interact with  The mass of living materials present in a
one another in a defined area and the particular place or in particular organisms.
physical factors in the region.  Can be measured in terms of mass of
 All ecosystems are dynamic (constantly carbon or dry mass of tissue
changing)
Efficiency of biomass transfer:
factors affecting ecosystems
Efficiency= biomass transferred x 100
Abiotic (non-living factors)
Biomass
 Light availability
Biomass at each trophic level is nearly always less
 Temperature
than the trophic level below as:
 Edaphic (soil) factors – different particle sizes
effect on the organisms that can survive in - Biomass consists of all cells/tissues of
them organisms, carbohydrates and carbon
 Oxygen availability compounds
 Water availability - When animals only eat only a small
proportion of the food they ingest that’s
Biotic (living factors)
converted into new tissue only this part of
 Interactions between organisms that are living the biomass is available for the next trophic
or have once lived level to eat
 Competition (intra/interspecific) for food/space
availability/partners to breed with