1. Learning Objective
To be able to:
Describe biotic and abiotic factors affecting a community
Key Words:
Community, abiotic, biotic

2. Biotic and Abiotic Factors
Sunday, 26 May 2019
Biotic and Abiotic Factors
Date and title in books. You need a pen, pencil & ruler.
Starter Activity – 3 minutes
Exam question

3. (F)
Target 1-9
State what is meant by a biotic and an abiotic factor
(F/H)
Target 4-9
State a range of biotic and abiotic factors for plants and animals
(H)
Target 5-9
Describe the consequence of change factors on a population and community
Extension: Application of Knowledge
Target 8/9
Evaluate the factors that effect the a community
Learning Outcomes

4. Biotic Factors
Biotic factors are the living organisms within an ecosystem that can cause change
They include:
Availability of food
New predators arriving
New pathogens
One species outcompeting another, so there are so few of them they cannot breed

5. Abiotic Factors
Abiotic factors are non-living factors that can change a community.
They include:
Light intensity
Temperature
Moisture levels
Soil pH and mineral content
Wind intensity and direction
Carbon dioxide (CO2) levels for plants
Oxygen (O2) levels for aquatic animals

6. Light Intensity
Rate of photosynthesis increases as the light intensity increases
Growth of plants will affect growth of animals

7. pH
Farmers spread quicklime on their soil to neutralise acidic soil to create optimum conditions for plant crop growth

8. Water and Humidity
More water
More photosynthesis
More growth

9. Intraspecific competition
Members of the same species population are competing for the same resources

10. Interspecific competition
Between individuals of different species within the same habitat or niche competing for the same resources

11. Predator-prey populations
How does the lynx population depend on the number of snowshoe hares? 50
estimated population size (thousands)
1800
1820
1840
1860
1880
1900
100
150
year
lynx
snowshoe
hare
Take a closer
look at this part
of the graph.

12. Predator-prey populations
Why does the peak for the lynx population always come after the peak for the number of snowshoe hares?
snowshoe
hare
150
lynx
For the populations
to survive, there must always be more hares than lynxes
100
estimated population size (thousands) 50
1845
1850
1855
1860
1865
year