4.1-4.9 organism in the environment, feeding relationships

Population

A group of organisms of the same species living in the sam place at the same time

Community

All of the populations living in the same area at the same time

Habitat

The place where an organism lives

Ecosystem

Interaction between a community of living organisms (biotic factors) and the non living parts (abiotic factors) of the environment

Biotic factors and examples

Living components eg. Food availability, new predators, new pathogens, competition

How does availability of food affect the community

More food means organisms have a higher chance of serving and reproducing, meaning populations can increase

How do new predators affect a community

• in balanced ecosystems, paradors catch enough prey to survive but no so they wipe out the prey population

• If a new predator is introduced, it may become unbalanced

How do new pathogens affect a community

If a new pathogen enters, the population will have no immunity or resistance so the population may decline

How does competition affect a community

If two species compete for same resources and one is better adapter, then it will outcompete the other causing a decline in the other species

Abiotic factors and examples

Non living components eg. Light intensity, temperature, moisture levels, soil pH and mineral content

How does light intensity affects a community

Light is required for photosynthesis

• more light leads to an increase in rate of photosynthesis and increase in plant growth rate

How does temperature affect the community

Affects the rate of photosynthesis in plants

How do moisture levels affect a community

Plants and animals require water to survive

How do soil ph and mineral content affect a community

Different species of plants are adapted to different soil ph levels and nutrient concentration levels

How does wind intensity and direction affect a community

• wind speed affects transpiration rate (loss of a plant’s water to its environment through evaporation) in plants

• Transpiration affects the rate of photosynthesis as it ensures water and mineral ions are transported to the leaves

How does Carbon dioxide levels for plants affect a community

CO2 concentration affects the rate of photosynthesis

How does oxygen levels for aquatic animals affect a community

Some aquatic animals like fish can only survive in water with high oxygen concentrations

What is ecology

The branch of biology that studies species distribution, abundance, interactions between species and their interactions with the abiotic environment

How to investigate population size of an organism in two different areas?

Quadrats - square frames used to estimate populations and study species distribution in an area by taking random systematic samples

Apparatus: quadrats, tape measures, random number generator, species key

Method:

1. Set up area by marking out your total study area (eg. 10×10m) with tape measures

2. Generate coordinates by using a random number generator to get coordinates within your marked area

3. Place quadrat at generated coordinates

4. Count the number of individuals within the quadrat

5. Repeat it in new random locations (eg 10 times)

6. Calculate mean per quadrat

7. Estimate total population: (total study area/quadrat area) x mean number per quadrat

8. Do for second area and compare and link to potential biotic/abiotic factors

What is the first trophic level

Producers - organisms that make their own food by photosynthesis

What is the second trophic level

Primary consumers - herbivores that only eat plants (producers)

What is the third trophic level

Secondary consumers - carnivores that eat primary consumers

What is the fourth trophic level

Tertiary consumers - carnivores that eat secondary consumers, they are the apex predators

What is the trophic level where an organism produces waste?

Decomposers- bacteria and fungi that breaks down dead animals body and waste for energy, using enzymes

What are food chains

diagrams that show the energy flow between organisms in an ecosystem

What are food webs?

Networks of interconnected food chains

What does a pyramid of numbers show?

• shows the population of each organism at each trophic level of food chain

• Producers are at the bottom and bars usually get smaller further up

What does a pyramid of biomass show

• It shows the relative dry mass of material at each level

• There is less biomass as you move up the trophic levels

How much as a percentage of biomass of each trophic level is transferred to the next?

10%

How is biomass transferred/lost?

• From the predator eating the prey

• Glucose used in respiration which produces carbon dioxide as a waste product

• Urea is a waste substance released in urine

• Lost as faeces

Efficiency of biomass transfers

(Biomass transferred to the next level/biomass available at the previous level) x 100