population
1. Meaning
A population is a group of living organisms of the same species living in a specific place at a specific time.
All humans in the world → Human population
All elephants in Africa → Elephant population
All neem trees in a garden → Neem tree population
2. What decides a population size?
Population size is controlled by four important factors:
a) Birth rate
The number of babies born.
More births → population increases.
b) Death rate
Number of deaths.
More deaths → population decreases.
c) Immigration
Organisms coming into an area.
(Example: birds flying into a forest)
d) Emigration
Organisms moving out of an area.
3. How populations grow
When birth rate + immigration is higher than death rate + emigration, the population grows.
Example:
If more people are born and fewer die → human population increases.
4. What controls population growth?
Population cannot grow endlessly. It is controlled by:
Food availability
Water
Space/shelter
Disease
1. Meaning
A population is a group of living organisms of the same species living in a specific place at a specific time.
All humans in the world → Human population
All elephants in Africa → Elephant population
All neem trees in a garden → Neem tree population
2. What decides a population size?
Population size is controlled by four important factors:
a) Birth rate
The number of babies born.More births → population increases.
b) Death rate
Number of deaths.More deaths → population decreases.
c) Immigration
Organisms coming into an area.(Example: birds flying into a forest)
d) Emigration
Organisms moving out of an area.
3. How populations grow
When birth rate + immigration is higher than death rate + emigration, the population grows.
Example:If more people are born and fewer die → human population increases.
4. What controls population growth?
Population cannot grow endlessly. It is controlled by:
Food availability
Water
Space/shelter
Disease
Predators
Climate
Natural disasters
5. Why population is important in ecology
Population helps scientists understand:
How species survive
5. Why population is important in ecology
Population helps scientists understand:
How species survive
How much food is needed
How organisms interact
How ecosystems stay balanced