Unit 7: Inheritance and Evolution pt2 Flashcards
What is an Ecosystem?
a unit consisting of a community
of living organisms and non living components
what is a biotic component?
living organisms
what is an abiotic component?
The physical aspects of an ecosystem
they provide the elements which all living organisms consist
What are the biotic factors?
Producers
Consumer
Saprobionts
What is a producer?
Ultimate source of energy in the food chain
plants - convert light energy into chemical energy
form the organic basis of all food chains
molecules produced by photosynthesis are consumed by other organisms
- are photoautographic
What is a consumer?
break down large insoluble organic compounds into smaller soluble molecules which are used to provide energy for growth
What is a primary consumer?
herbivores
What are secondary, tertiary consumers?
carnivores
What are Saprobionts?
bacteria and fungi which break down dead organisms and are essential for the recycling of nutrients in the environment
What abiotic factors affects size and population?
light
pH
temperature
water
oxygen
co2
what forms a community?
all living organisms of all species
what is a niche
an organism is abiotic requirement in the habitat and its position in the food web
- description of how organisms fit into the ecosystem
how can you estimate the size of a stationary population?
using quadrats
describe random sampling
area is divided into a grif
Coordinates are selected using a random number generator and a quadrat is placed
large number of quadrants must be used so results are representative
when would you use transects?
When measuring the abundance of organisms over an area where changes in the community occur
Describe how a belt transect is used
The table went along the ground in a straight line
At regular intervals, a Quadat is laid down and species within are counted
The frequency of species is recorded
which calculations can you use to measure the abundance of an organism?
using it’s frequency or percentage cover
How do you measure a frequency of an organism?
- The likelihood of a particular species occurring in a quadrat
OR
-The number of individuals in each quadrant
How do you calculate percentage cover?
estimated by eye
The proportion of the ground area covered by the stems/leaves of the species
How can you calculate the mean density of species in a study area?
total number of individuals counted
—————————————————
no. if quadrats x area of each quadrat
What is the calculation for population size?
mean density x total area
What is the mark release recapture method used for?
estimate the population of mobile animals
describe the mark recapture method
- Capture a representative sample of organisms in a population and record the number and mark them
(mark in a way which doesn’t affect survival) - release back into habitat and leave them for suitable period of time to let them mix randomly
- Capture a second sample I count the number of marked individuals
how do you calculate population size after market release recapture?
no. in first sample x no. in second sample
————————————————————
no. marked in second sample
What are assumptions does the mark release recapture method rely on?
- organisms mix randomly
- sufficient time must pass between capture and recapture to allow random mixing, less mobile the species longer the timelapse
- organisms disperse evenly
- changes of population due to immigration births/deaths are negligible
- marking does not hinder movement/survival
What can affect the size of populations in an ecosystem?
- The effect of abiotic factors
- Interactions between organisms
- intra- inter- specific competition
- Predation
How does light affect population size?
affects photosynthesis and number and diversity of plant species
therefore, the number and type of consumers and ecosystem
How does pH affect population size?
affects activity of enzymes
Acidic and alkaline soils favour the growth of specific plant species
How does temperature affect population size?
metabolic processes (respiration/photosynthesis) all controlled by enzymes
- Low temperatures are a limiting factor for photosynthesis
- High temperatures can cause enzyme denaturation
- In aquatic habitat and increasing temperature reduces the amount of dissolved oxygen available
What is a mutualistic relationship?
A relationship were two organism and benefit from the association
What causes small communities?
harsh habitats and extreme abiotic factors
These mean that only few species can survive
What causes an unstable ecosystem?
When species diversity is low as the food web is limited
What causes a stable ecosystem?
greater diversity as there’s more resources available at each trophic level
the loss of one species will have a limited effect on the ecosystem
what is an inter specific competition?
competition between different species
Plants compete for light and soil etc
animals compete for the same prey and water supply etc
what is intra specific competition?
competition within the same species
More intense as organisms are competing for identical resources can we stop this?
What is Predation
an interspecific interaction
Predator/prey relationships are important in controlling population size
increasing prey results in a larger predator population
but as prey ate consumed their population size begins to fall then but it’s a population decreases
What happens if a particular prey is removed from an ecosystem?
it disrupts feeding relationships as the predator will then feed on another prey species
What is primary succession?
The gradual change in plant/animal communities
from colonisation by Pioneer species to the climate community
outline primary sucession
- pioneers species colonise an area (lichens or algae)
- when they die, they decompose and for mineral rich soil for the next group to colonise the area
- new species outcompete the old organisms and change the environment making it more suitable for others ( making soil more fertile)
- each of these different communities is considered part of a succession, each stage species change their abiotic environment
- A series of more complex species will colonise the area eventually a climate communities formed
- As the number/complexity of plant species increase theres an increase in the variety of niches/food resources with resulting changes in animal populations
- Stability/diversity increases as food will become more complex
Why may climax community not be established?
agricultural practices, e.g. grazing crop production ploughing, etc
- natural events such as fires/floods can also prevent succession
What is grazing?
seedlings of plants are continually eaten preventing any succession beyond grassland
What is ploughing?
seedlings are broken up and buried preventing germination
seeds of crops species are then sown
use of herbicides maintains an established community
