Plants contain plant cells and animals
contain animal cells.
An animal cells is much simpler than the plant cell. This is
because plant make their own food however animals do not.
Plant cells contain chloroplasts which is where
photosynthesis happens.
Nucleus: contains genetic material,
which controls the activities of the cell.
Cytoplasm: most chemical processes
take place here, controlled by enzymes.
Cell membrane: controls the movement
of substances into and out of the cell.
The plant cell has additional things- Cell wall:
strengthens the cell. Chloroplasts: contains chlorophyll,
which absorbs light energy for photosynthesis to
happen. Permanent vacuole: filled with cell sap to keep
the cell turgid (enlarged and swollen with water).
Predators and
Prey
An example of a predator is that of a lion, tiger,
wolf and alligator. An example of prey is snail,
gazelle, deer and rabbit.
Predators and prey are involved in food
chains and food webs...
Food Chains
The arrows in a food chain represent the
flow of energy through the ecosystem.
Organisms like algae and phytoplankton are primary producers. They photosynthesise to make their own
food, however animals then eat them. Plankton and algae are eaten by jellyfish. This animal is called a
herbivores. They are then eaten by primary consumers like sea turtles. The energy is passed through the
animals but some is lost through things like faeces, movement and reproduction. The primary consumers
are then eaten by secondary consumers like sharks. You now have a food chain!
Pyramid of
Biomass
It can be difficult to make a pyramid of biomass as;there might be
issues measuring dry biomass and an organism may belong to
moer than one trophic level.
The wider the bar, the bigger biomass is has. The
pyramid of biomass can look very different to the
numbers...
In this example, the biomass of the producer is
greatest and the sparrow hawk the least.
Habitats and
Adaptations
A habitat, or a biome, is the type of environment in which plants and animals
live. A habitat is dictated by what kinds of plants grow there, the climate and
the geography. Rainforests, coral reefs and tundras are all habitats where
particular plant can be found.
Animals and plant adapt to their surroundings however can take
centuries! One adaptation example is that of an elephant; big ears
for good hearing, fat pads to absorb shock energy in feet and many
more.
There are behavioural
adaptations and physical
adaptations. Both effect the
animal or plant.
Some adaptations make animals or plants thrive
while others... don't really help at all!
Investigation of Natural
Habitats
Various tools are used to do this. For example a Quadrat which is a
square 1/2 metre by 1/2 metre. It is used to study the distribution of an
item covering a large area.
A trundle Wheel has the exact circumference of 1 metre so
that every time it does a full rotation, the length can be
counted easily. It makes a click every time it does this. It
can be used for long-distance measurements like the
perimeter of a field.
A Transect is a process where scientists
measure using quadrants in a staring line.
Photosynthesis
A plant takes in CO2 and water in order to make
glucose and oxygen. It uses the sunlight to change
these two compounds into a sugar.
Photosynthesis can be effected by things called limiting factors. Some
limiting factors of photosynthesis include temperature, carbon dioxide levels
and the light intensity.
Plants turn the glucose into starch as it is not water soluble. The change is
a reversible change so it can be changed back into glucose.
This process takes place in the chloroplasts which contain chlorophyll
(a green substance). In the cross section of a leaf, it takes place
mostly in the palisade cells. As well as this it takes place, not as much,
in the spongy mesophyll.
There are air gaps between the mesophyll to allow easy gas
exchange. Respiration in plants takes in O2 and gives out CO2
whereas photosynthesis takes in CO2 and gives out O2. The symbol
equation for photosynthesis is; H2O + CO2 --> O2 + C6H12O6.
Food Webs
It is a system of interlocking,
independent food chains.
If for example the population of slugs decreased, so would the rest of
the species as one thing can impact many. If rabbits and insects also
eat grass, with not many slugs around, the is more grass for other
species so they would thrive. Their populations would increase. But in
turn, other animals would have to eat more insects, and all that is
left is the rabbit. They would over populate! Some animals can eat
more of one thing, while others may starve or die...