Download Biology Standard SB4 (b)

The flow of matter and energy through ecosystems
The flow of energy
 In a food chain, energy is passed from one link to another. When a
herbivore eats, only a fraction of the energy (that it gets from the plant
food) becomes new body mass; the rest of the energy is lost as waste or
used up by the herbivore to carry out its life processes (e.g., movement,
digestion, reproduction). Therefore, when the herbivore is eaten by a
carnivore, it passes only a small amount of total energy (that it has
received) to the carnivore. Of the energy transferred from the herbivore
to the carnivore, some energy will be "wasted" or "used up" by the
carnivore. The carnivore then has to eat many herbivores to get enough
energy to grow.
Because of the large amount of energy that is lost at each link, the
amount of energy that is transferred gets lesser and lesser ...
The further along the food chain you go, the less food (and hence
energy) remains available.
The energy pyramid
Carnivores are contained
on the top level.
Your primary consumers
are in level two.
Level one houses
the producers.
Producers get
their energy from
the sun.
Carnivores are the fewest in
numbers in a healthy
ecosystem. The carnivore has
to eat a lot to get enough
energy to live.
The primary consumers are
herbivores they eat the plant
life. A percentage of the
energy is used by the
herbivores the rest becomes
waste.
In a healthy
ecosystem this is
the largest
group.
Photosynthesis
Photosynthesis - The cycle of
plants and how they make
energy! The sun(light energy),
water, minerals and carbon
dioxide are all absorbed by the
plant. The plant then uses
them to make glucose/sugar,
which is the energy/food for
the plant. Oxygen is also
produced by the plant in this
cycle, which is then let off into
the air! Have you noticed how
clean and pure the air feels
when there are plants around?
They are filling the air with
oxygen!
The Water Cycle
 The Water Cycle (also known as the hydrologic cycle) is the journey
water takes as it circulates from the land to the sky and back again.
The Sun's heat provides energy to evaporate water from the Earth's
surface (oceans, lakes, etc.). Plants also lose water to the air (this is
called transpiration). The water vapor eventually condenses, forming
tiny droplets in clouds. When the clouds meet cool air over land,
precipitation (rain, sleet, or snow) is triggered, and water returns to the
land (or sea). Some of the precipitation soaks into the ground. Some of
the underground water is trapped between rock or clay layers; this is
called groundwater. But most of the water flows downhill as runoff
(above ground or underground), eventually returning to the seas as
slightly salty water.
This is how the water cycle works
The Nitrogen Cycle

Nitrogen is a component of many organic molecules. It forms an essential
part of amino acids (which make up proteins) and DNA. Nitrogen is essential
for all living cells.
 What is the nitrogen cycle?
Nitrogen is the major component of earth's atmosphere. It enters the food
chain by means of nitrogen-fixing bacteria and algae in the soil. This nitrogen
which has been 'fixed' is now available for plants to absorb. These types of
bacteria form a symbiotic relationship with legumes--these types of plants are
very useful because the nitrogen fixation enriches the soil and acts as a 'natural'
fertilizer. The nitrogen-fixing bacteria form nitrates out of the atmospheric
nitrogen which can be taken up and dissolved in soil water by the roots of
plants. Then, the nitrates are incorporated by the plants to form proteins,
which can then be spread through the food chain. When organisms excrete
wastes, nitrogen is released into the environment. Also, whenever an organism
dies, decomposers break down the corpse into nitrogen in the form of
ammonia. This nitrogen can then be used again by nitrifying bacteria to fix
nitrogen for the plants.
The Nitrogen cycle in the soil
The Carbon Cycle
 Carbon moves from the atmosphere to plants.
In the atmosphere, carbon is attached to oxygen in a gas called carbon dioxide
(CO2). With the help of the Sun, through the process of photosynthesis, carbon
dioxide is pulled from the air to make plant food from carbon.
 Carbon moves from plants to animals.
Through food chains, the carbon that is in plants moves to the animals that eat
them. Animals that eat other animals get the carbon from their food too.
 Carbon moves from plants and animals to the ground.
When plants and animals die, their bodies, wood and leaves decay bringing the
carbon into the ground. Some becomes buried miles underground and will
become fossil fuels in millions and millions of years.
 Carbon moves from living things to the atmosphere.
Each time you exhale, you are releasing carbon dioxide gas (CO2) into the
atmosphere. Animals and plants get rid of carbon dioxide gas through a process
called respiration
The carbon cycle
Phosphates in the web of things
 Phosphate is mainly present in bones in animals, but is
incorporated in most tissues of plants and animals and through digestion gets absorbed and incorporated
in a person's body and is dynamically present, being
released and excreted through urine and feces. Thus
excreted phosphate returns to the environment where
it is available for uptake into plants and into the food
web.
Phosphates are everywhere
The process as a whole
The plants produce energy from the sun. The energy from the sun is partly
stored within the plant, which is eaten by the herbivores. Some of the
energy taken from the plants is stored and the rest is waste which falls back
to the soil and becomes nutrients that feeds the soil. The carnivores and
omnivores then eat and some of that energy is used and the rest is waste.
The decomposers turn the waste into a fuel source that keeps a healthy
ecosystem.