The gradual change in the
distribution of species across a
habitat
A gradual change in abiotic
factors can lead to the zonation of
organisms in a habitat
A coastal zone;changes in salinity and soil
depth where different types of
plants grow
Biodiversity=a measure of the variety of life in
an area. A high level of biodiversity is healthy
because if conditions in a habitat change some
organisms will survive
Population
Population is all the organisms of one species in a habitat
Community is the population of different species in on habitat
population size = number in first sample x
number in second sample / number in
second sample previously marked
Capture-Recapture... 1.Capture a sample of the
population and mark animals. 2 Release them back
into the environment. 3. Recapture another sample
of the population, count how many of this sample are
marked. 4. Estimate population size using the
equation.
Photosynthesis
6CO2 + 6H2O --> C6H12O6 + 6O2
Van Helmont : Decided that plants gain mass by taking in water. He dried soil and
put it in a pot. He then planted a 2.2kg tree in the soil. He watered the plant
whenever it was dry. 5 years later he removed the plant and it weighed 76.7kg. The
mass of the soil changed very little so he concluded that the tree gained mass by
taking in the water
Water is split by light energy into oxygen and hydrogen ions.
Glucose is converted into other substances... 1. For respiration. 2.
Making cell walls (glucose is converted into cellulose). 3. Stored in
seeds (glucose is tuned into lipids) 4. Stored as starch (for use
when photosynthesis is not happening at night, starch is insoluble
so it does not dissolve or affect water concentration) 5. Making
proteins (by combining with nitrates.
Diffusion
The net movement of particles from a
region of high concentration to low
concentration
The rate of diffusion is increased if....
Molecules have a short distance, a
large surface area and a large
concentration gradient.
Transport in plants
Xylem : Carries water and minerals from the roots and leaves (one
way). Adapted to form xylem vessels when cells die to carry water and
extra lignin to make it strong. Aids photosynthesis
Phloem : Carries dissolved foods from leaves to the rest of the plant. Adapted:Cells are
alive to pass sugars to other cells, long and thin to transport sugar. Aids respiration and
storage of starch.
Decay
The break down of dead plants and animals
what is needed for decay? 1. Microorganisms (fungi or bacteria) 2. Heat
energy for respiration (fungi 25' Respiration 37') 3. Oxygen for aerobic
respiration. 4. Moisture
Preserving food.... -Vinegar creates an acidic environment which
kills harmful bacteria and fungi in food. -Freezing slows down
reproduction of bacteria. -Canning -Sugar or Salt means bacteria
lose water which damages the cell e.g osmosis
Intensive Farming
Trying to produce as much food as possible from your land
Methods ; Using herbicides to kill weeds (means that the
energy from the sun falls to the crops and not competing
plants like weed, Using pesticides to kill insects that eat
crops (this makes sure no energy is transfered into a
different food chain and is all saved for growing crops),
Battery farming animals (animals are kept indoors so they
are warm and cannot move about which saves energy from
the animals moving round and trying to keep warm
Disadvantages - Careless use of fertilisers can pollute rivers and lakes (eutrophication).
-Pesticides disturb food chains -Some people think intensive farming of animals is cruel as they
cant move around