Transcript Number decreases Size increases

Pyramid Of Numbers
Number decreases
Size increases
FOX
RABBIT
GRASS
The Pyramid of Biomass
A pyramid of biomass shows the total
biomass at each stage of a food chain.
Biomass is the mass of all the organisms
in that population.
Biomass goes down as you move along a
food chain, so this gives a pyramid shape.
HOMEWORK
Set Tues 28 August Due Fri 31 Aug
Biosphere Booklet
Questions 1 - 17
Population
The number of organisms of the
same species present in an
ecosystem
What does the growth rate of a
population depend on ?
• Birth rate is measured by counting the
number of live births in a population during an
interval of time
• Death rate is measured by the counting the
number of deaths in a population during an
interval of time
• The growth rate of a population depends on
the birth and death rates.
Population Growth
Left unchecked a population
will grow Exponentially!
This is called a ……
Population
Explosion
Human Population Growth
The Human Race is
undergoing a
Population
Explosion.
The growth curve of a population in ideal
conditions continues to rise indefinitely
because the birth rate is high and the death
rate is low.
Factors Limiting Population
Growth
Disease/Parasites
Lack of Space
Predators
Limiting Factors
Starvation
Natural Disasters
Predation
Abundance of
Food
Competition
Plants compete for …
• Light
• Water
• Nutrients
Animals compete for …
• Food
• Water
• Shelter
• Nesting Sites
• Mates
Transparent
Lid
Damp
Cotton
Wool
Radish Seeds
Only
Cress Seeds
Only
Radish and Cress
Seeds
After 5 Days at 240C
Healthy
Radish
Healthy
Cress
Healthy Radish
Sickly Cress
If the competing individuals are of the same
species their needs will be almost identical so
the competition will be even more intense !
This results in the stronger more successful
competitors surviving and the weaker
competitors dying off.
The Nitrogen
Cycle !
Nitrogen
Gas
Denitrification
by Bacteria
Nitrogen
in
Animals
Lightening!
Nitrogen
in
Plants
Death and
Decay
Nitrogen in
Ammonium
Compounds
Nitrogen in
Nitrites in
Soil
Nitrogen
in Soil
Nitrates
Keeping It Balanced!
Leaching
Lightening
Fertiliser
Nitrogen
Fixing
Bacteria
NItRATES
Cropping
Denitrifying
Bacteria
• Nitrogen Cycle Questions
1. How much nitrogen gas is there in the air? (1)
2. How can nitrogen be removed from the air? (3)
3. How can nitrogen be added to the air? (1)
4. How can nitrogen be added to the soil? (4)
5. What happens to the nitrogen in the soil? (2)
6. What happens to the nitrogen in plant proteins?
(2)
7. How does decay of organisms and their wastes
add nitrogen to the soil? (3)
• ANSWER IN FULL SENTENCES