POPULATION: All the organisms of one species in a habitat.
COMMUNITY: Populations of different species in a habitat.
QUADRAT: A square frame enclosing a known area.
Scaling up from a quadrat
1. Count all the organisms in 1m square.
2. Multiply the number of organisms by the total area of the habitat.
Estimate Population Size: CAPTURE-RECAPTURE
1. Capture a sample of the population and mark them in a harmless way. Release them back into their environment.
2. Recapture another sample. Count how many are marked. Estimate the size of the population from the sample: (number in first sample x number in secon sample) / number in second sample previously marked.
Sample size affects accuracy - THE BIGGER THE SAMPLE, THE MORE ACCURATE THE ESTIMATE IS.
Assumptions when using Capture-Recapture
1. There have been no changes in POPULATION SIZE - (deaths, immigration (organisms moving into the area) and emmigration (organisms moving out of the area))
2. The sampling method for the Capture and the Recapture were identical (pit fall trap set up in the same way each time.
3. The marking hasn't affected the organisms chances of survival (e.g making them stand out to predators)
Ecosystems and Distribution
ECOSYSTEM: All the organisms living in a particular area (as well as the non-living ABIOTIC factors)
HABITAT: The place where an organism lives.
Ecosystems are self supporting: They contain almost everything they need to maintain themselves. Water, nutrients and elements (e.g carbon) are recycled within the ecosystem). The only thing an ecosystem gets from outside, is the energy source. The SUN.
DISTRIBUTION: Where organisms are found within a particular area.
Transects: Investigate the distribution of organisms
1. Mark out a line using a tape measure. Place quadrats all along the line. Count and record the number of organisms in each.
2. If it's difficult to count all the organisms, find the % cover. (Estimating the % covered by that organism by counting the number of squares). The data can then be displayed on a kite diagram.
They show the distribution and abundance of organisms along a transect line.
DISTRIBUTION: Where organisms are found in a particular area.
ABUNDANCE: The number of organisms found.
The ABUNDANCE is shown by the thickness of the kite shape. Abundance is plotted above and below the central line, so it's symmetrical.
The x axis shows the distance along the transect line.
The y axis shows the % abundance of the organism.
ABIOTIC FACTORS: All the non-living, physical factors in an environment - e.g. light, temperature, soil quality, oxygen levels, salinity (salt levels) and water.
The DISTRIBUTION of organisms is affected by ABIOTIC factors because:
1. Organisms are adapted to living in certain physical conditions: they're more likely to survive and reproduce in areas with these conditions.
2. Many organisms can ONLY survive in the conditions they're adapted to.
ZONATION: The gradual change in the distribution of species across a habitat.
A gradual change in the ABIOTIC factors can lead to ZONATION of organisms in a habitat.
MARRAM GRASS is adapted to salty conditions. LICHENS AND MOSSES are adapted to less SALINE conditions. HEATHER AND GORSE (SHRUBS) are adapted to lower SALINITY and deeper soil. TREES (e.g. BIRCH and OAK) are adapted to very low SALINITY and very deep soil.
BIODIVERSITY: A measure of the variety of life in an area.
1. The amount of variation between individuals of the same species in an area.
2. The number of different species in an area.
3. The number of different habitats in an area.
ECOSYSTEMS WITH A HIGH LEVEL OF BIODIVERSITY ARE HEALTHIER. More DIVERSE ecosystems are better able to cope with changes in the environment.
NATURAL ECOSYSTEMS: Maintain themselves without any major interference from humans
ARTIFICIAL ECOSYSTEMS: Created and maintained by humans.
Biodiversity: Native Woodland
1. Variety of tree species.
2. Trees are different sizes and different ages.
3. Variety of plant species.
4. Variety of habitats (different trees and plants for habitats to be made in).
5. Variety of animal species
Biodiversity: Forestry Plantation
1. One species of tree is planted for timber
2. Blocks of trees are planted at the same time (many are the same age).
3. Fewer plant species (trees are densely planted so there is less room and light for other plants to grow).
4. Fewer habitats (there aren't enough plant species to create them).
5. Fewer animal species (there aren't as many habitats or sources of food).
Biodiversity: Lakes/Fish Farms
1. Many different fish species.
2. Variety of plant species.
3. Variety of animal species.
1. One fish species is farmed for food.
2. Fewer plant species (food waste from fish food causes algal blooms, blocking out light; killing plants).
3. Fewer animal species (predators are kept out and pests are killed).
Uses energy from the SUN to change CARBON DIOXIDE and WATER into GLUCOSE and OXYGEN. Takes place in the CHLOROPLASTS in plant cells which contain pigments like CHLOROPHYLL that absorbs light energy.
6CO2 + 2H2O = C6H12O6 + 6O2
2 main stages of photosynthesis
1. Light energy is used to split water in oxygen gas and hydrogen ions.
2. Carbon dioxide then combines with the hydrogen ions to make glucose and water. The oxygen is left.
WATER IS NOT ONE OF THE OVERALL PRODUCTS OF PHOTOSYNTHESIS (as more is used up in the first stage than is produced in the second stage.
How plants use glucose
1. RESPIRATION - Some of the glucose is used for respiration. This releases energy so they can convert the rest of the glucose into other useful substances.
2. MAKING CELL WALLS - Glucose is converted into CELLULOSE for making cell walls.
3. STORED IN SEEDS - Glucose is turned into LIPIDS (fats and oils) for storing in seeds.
4. STORED AS STARCH - Glucose is turned into STARCH and stored in roots, stems and leaves, for use when photosynthesis isn't happening e.g at night.
- Starch is INSOLUBLE so good for storing. - It can't dissolve in water and move away from the storage areas in solution. - It doesnt affect the water concentration inside cells (soluble substances would bloat the storage cells by taking in water).
5. MAKING PROTEINS - Glucose is combined with NITRATES from the soil to make AMINO ACIDS which are then made into PROTEINS. These are used for growth and repair.