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Biology – notes
1.
Ecosystem: all organisms in an area that
interact with each other and with their
environment.
a) Ecosystems found on dry land are
called
terrestrial ecosystems.
Ex: Tropical forest, deserts, Tundra,…
b) Ecosystems found under water are
called
aquatic ecosystems.
Ex: Sea, Lake, River,…
2. Producers: plants that can use
photosynthesis to convert radiant
energy from the sun into food
(chemical energy) for themselves and
the animals in their ecosystem.
3. Consumers: animals that feed on
plants or other animals in order to get
their energy.
4. Primary consumers: animals, such as
rabbits and deer, that eat plants. They
are also called herbivores.
5.
6.
Secondary consumers: animals, such
as foxes and wolves, that feed on the
plant-eaters. They are either
carnivores if they eat meat or
omnivores if they eat both plants and
meat.
The energy source for all ecosystems is
the Sun. Sunlight is captured by plants
during photosynthesis and is passed
through the ecosystems from species to
species when herbivores eat plants and
carnivores eat herbivores. These
interactions form a food chain.
7.
•
•
Trophic level: feeding levels of the
organisms in a food chain or food web.
a) 1st level = plants
b) 2nd level = herbivores
c) 3rd level = carnivores that eat
herbivores.
d) 4th level = carnivores that eat
carnivores.
The amount of energy that is transferred
from one trophic level to the next varies
from about 5 to 20 percent, with 10%
commonly used as an average.
Decomposers, such as bacteria and fungi
can consume from the 2nd level on…
because they consume any remaining dead
plant and animal matter.
8. Scavengers: consumers that feed on
the bodies of larger dead animals.
9. Detritivores: consumers that feed on
the bodies of smaller dead animals,
dead plant matter and animal dung.
10. Carrying capacity: is the largest
population of organisms an
environment can support.
11. Competition: struggle among
individual organisms for access to
limited resources such as food or
territory.
12. Intraspecific competition: competition
among individuals of the same
species.
13. Interspecific competition: competition
among individuals of different species.
14. Population density: How many
individuals can live in an area at the
same time.
15. Density-dependant factors: variable
that affect a population based on the
degree of crowding within the
population. Ex: AIDS
16. Density independent factor: variables
that affect a population regardless of
the density. Ex: forest fire
17. Carbon cycle: (2 phases to provide carbon
to all organisms as carbon is the key
element of organic compounds)
a) Photosynthesis: Producers gather the
carbon dioxide (CO2)from the air,
water(H2O) form the soil into their
chloroplasts. With the help of sunlight
energy, they transform these compounds
into carbohydrates(C6H12O6) and
oxygen(O2).
b) Cellular respiration: All eukaryotes
organisms, in their mitochondria's, get their
energy by using these carbohydrates along
with oxygen from the air and they return the
carbon dioxide back to the atmosphere.
18. Nitrogen cycle: nitrogen is an essential
component found in living things.
a) Nitrogen-fixing bacteria found in the roots
of some legumes take in nitrogen gas and
convert it into ammonia or nitrates.
b) Decomposers degrade waste and dead
matter into ammonia.
c) Nitrifying bacteria found in the soil change
the ammonia into nitrates that when dissolved
into water can be absorbed and used by
plants.
d) The denitrifying bacteria convert excess
nitrates back into nitrogen gas that will be
sent back into the atmosphere.