ORGANISMS IN THEIR

ENVIRONMENT

1- Ecosystem: A group of living organisms and their

environment interacting with each other.

2- Community: All the dif ferent species of organisms that

make up that are found in a given area.

3- Population: All that individuals of one species of an

organism.

4- Habitats: The place in which organism live

IMPORTANT DEFINITIONS IN

ECOSYSTEMS

AN ECOSYSTEM

This is a series of organisms which feed off of each other.

A food chain starts with a producer and ends with a

decomposer.

Producer: Plants

Primary consumer: Herbivore (animal)

Secondary consumer: Carnivore

Tertiary consumer: Carnivore

Decomposer: Bacteria/Fungus

Each step in a food chain is called a trophic level.

FOOD CHAINS

EXAMPLE OF A FOOD CHAIN

1- in a food chain, energy is changed from one form to

another.

For example, when solar energy is absorbed by plants, it is

converted into chemical energy in food. Then, that plant will

respire giving out energy as heat. Then, when the primary

consumer eats the plant, it respires some of the plant losing

some of its energy and also since it doesn’t eat every bit of

that plant some of the energy remains in the plant. That

means that the original solar energy was not completely

passed from one trophic level to the next.

ENERGY LOSS IN FOOD CHAINS

A series of food chains interacting with each other.

FOOD WEBS

A- pyramids of Numbers

B- Pyramids of Biomass

C- Pyramids of Energy

REMEMBER that the food chain begins at the base of the

pyramid and ends at the apex!

MANIPULATING FOOD CHAINS IN THE

FORMATION OF DATA

Think about this food chain,

Grass Antelope Leopard.

Grass is the most in number and since it’s the beginning of

the food chain, it makes up the base of the pyramid.

The antelopes that eat the grass are less than grass in

number, but more than the leopard, so they form the middle

of the pyramid

The leopard which is the last organism of the food chain is the

least in number, therefore forming the apex

A- PYRAMIDS OF NUMBERS

A- PYRAMIDS OF NUMBERS

Another example,

Tree leaf eating insects insect eating birds birds of prey

A- PYRAMIDS OF NUMBERS

SAMPLE QUESTION

These pyramids are built depending on the MASS of organisms.

Tree leaf eating insects insect eating birds birds of prey

B- PYRAMIDS OF BIOMASS

Since energy is lost along the food chain, the pyramid will

look like the following:

Cabbage Snails Birds Birds of prey

C- PYRAMIDS OF ENERGY

THE WATER CYCLE

The water cycle is made up of 3 main parts:

1) Evaporation:

a) Water is lost from the sur face of water bodies such as

Oceans, Seas….. Etc.

b) Water is lost from leaves via TRANSPIRATION.

2) Condensation:

The process by which the water vapour is conver ted into clouds.

This happens because in the sky the temp. is colder than on the

sur face of the ear th.

3) Precipitation:

The process by which the condensed water returns to the ear th in

one of the fol lowing forms:

a) Rain

b) Hail

c) Sleet

d) Snow

EXPLANATION OF THE WATER CYCLE

THE CARBON CYCLE

There is a 0.04% carbon dioxide in the atmosphere

A) USE OF CARBON:

Plants use up the carbon dioxide for photosynthesis.

The carbon is stored in the glucose that is made during photosynthesis.

B) RETURNING CARBON:

1) Plants respire to return carbon in CO2.

2) Animals eat the plants and then respire to return carbon in CO2.

3) Plants/Animals die and are decomposed by decomposers which return CO2 by respiration.

4) Combustion of fossil fuels.

EXPLANATION OF THE CARBON CYCLE

Too much carbon dioxide in the atmosphere results in the

earth becoming warmer. (another gas that contributes to

global warming is methane)

This comes about as the result of the suns rays being trapped

on the earths surface because of the dif ference in wavelength

changes.

You see when the suns rays descend to earth they come with a

certain wave length, the moment they hit the earths surface,

their wave length changes as the bounce back off the earths

surface. These waves can’t leave the earths surface because

there is a blanket of co2 trapping it. This results in the

heating of the surface of the earth.

GLOBAL WARMING

1) Deforestation: Humans cut down trees to make space or to

use the wood for particular purposes. The less trees there are

the less co2 that can be absorbed for photosynthesis.

2) Burning fossil fuels: just count how many cars you have in

the garage and it will all make sense! Cars, Heating, Planes

etc.

HUMAN INFLUENCES ON GLOBAL

WARMING

NITROGEN CYCLE

There is a 78% Nitrogen concentration in the atmosphere.

Nitrogen is inert (unreactive)

But….we need nitrogen to make amino acids and hence

proteins.

So how can we use this INERT gas? Easy look @ the next slide.

NITROGEN CYCLE EXPLANATION

A) Making use of the Nitrogen:

Nitrogen can be used in one the following ways:

1) Lightning: the energy in a strike of l ightning will cause force the nitrogen and oxygen to fuse into nitrogen oxides. These oxides are dissolved in rain water and are carried into the soil to form NITRATES.

2) Nitrogen fixing bacteria: these are found In the nodules of some plants l ike LEGUMES. This bacteria forces the nitrogen and oxygen to combine forming NITRATES.

3) Haber process: it is an industrial process in which nitrogen and hydrogen are made to react with each other to form AMMONIA. The ammonia is used to make fertl isers (example: Ammonium nitrates)

Note: the Nitrates and the ammonia can then be taken up by the roots of plants. Plants then use these to make amino acidsproteins.

NITROGEN CYCLE EXPLANATION

Returning the Nitrogen:

1) Excretion of urea can return nitrates to the soil.

2) the death of an organism results in 2 types of bacteria playing a role in returning nitrogen

a) Nitrifying Bacteria in the soil: returns the nitrogen stored in proteins to nitrates or ammonia in the soil. (This is useful for other plants )

b) Denitrifying Bacteria: Turns ammonia and nitrates back to nitrogen which is left to go into the atmosphere.

Note: without the nitrogen cycle there is no chance of us getting any proteins.

NITROGEN CYCLE CONT’D

POPULATION SIZE