Energy and ecosystems Flashcards
Define net primary productivity
Total chemical energy available for plant growth, plant reproduction and energy transfer to other trophic levels after respiratory losses.
Define gross primary production.
Total chemical energy in plant biomass within a given volume or area.
What is the relationship between GPP and NPP?
NPP = GPP - R
where R is the respiratory losses from plants
What is biomass?
Total dry mass of tissue or mass of carbon measured over a given time in a specific area.
What is the unit for biomass?
Area gm^-2
Volume gm^-3
Why does biomass decrease at each trophic level?
- energy is lost in nitrogenous waste (faeces/ urine)
- Some of the organism is not consumed
- Energy lost to surroundings as heat
What is the equation for % efficiency?
(energy converted to a useful form (J)) x 100 / total energy supplied (J)
State what is meant by the term ecosystem.
organisms and abiotic/ non - living factors
Define community
All the different species that live in one area and interact with each other.
How do niches affect the abundance and distribution of organisms in a habitat?
No two species can occupy the same niche; interspecific competition excludes one species or the niche is divided according to its adaptations.
What is meant by primary succession?
When an area previously devoid of life is colonised by a community of organisms.
Summarise the process of primary succession
- pioneer species can survive harsh conditions and colonise the area.
- They change abiotic factors of their environment e.g decomposition adds nutrients to the ground
- Over time, more complex organisms survive and outcompete the initial species.
What is a climax community?
Final seral stage of succession. Ecosystme is stable in dynamic equilibrium over a long period of time. Usually dominated by large trees or shrubs in rich soil.
What is evolution?
Change in allele frequency in gene pool of a population. Results in development of new dominant characteristics.
How does natural selection lead to evolution?
- Random mutations result in new alleles
- Some alleles provide an advantage, making an individual more likely to survive and reproduce.
- Offspring recieve the new allele and frequency increases over many generations. Frequency of unfavourable alelles decreases.
Define speciation
When a population is split and reproductively isolated, there are different selective pressures on the two groups. If the genetic makeup changes to the extent the two groups can no longer interbreed, they have become separate species.
What is meant by allopatric speciation?
Speciation resulting from a physical barrier e.g river, mountain range. The environments occupied by the two groups are different, and therefore different alleles are favoured.
What is meant by sympatric speciation?
Speciation resulting from a non -physical barrier e.g mutation that no longer allows two organisms to produce fertile offspring. Any changes in anatomy or behaviour may also prevent breeding.
How can we analyse evolutionary relationships on a molecular level?
Genomics: gel electrophoresis, DNA sequencing, bioinformatics.
Proteomics: analysis of amino acid sequence.
How do proteomics and genomics support the theory of evolution?
Universal code. Species with fewer differences in base sequence have more homologous characteristics. Suggests diversion form common ancestors.
