BIOLOGY 4.0

ECOLOGY IN THE LOCAL ENVIRONMENT
1. ESTIMATING POPULATION SIZES
  1. Population = all the organisms of one species in a habitat
  2. Community = populations of different species in a habitat
  3. QUADRAT
    1. A square frame enclosing a known area
      1. You can study the small area within a quadrat and scale up your findings to make estimates for larger areas
        est population = average per quadrat x number of quadrats possible
  4. CAPTURE- RECAPTURE
    1. 1) Capture sample of population & mark animals in a harmless way & release them back in to the environment
      1. 2) Recapture another sample of population & count how many of the sample are marked
        population size = (number in 1st sample) x (number in 2nd sample) / number in 2nd sample marked
    2. ASSUMPTIONS
      1. No death, immigration or emigration took place
      2. You used identical sampling methods each time
      3. The marking process had no effect on the rate of survival
2. ECOSYSTEMS
  1. All the living organisms (biotic factors) and non-living (abiotic factors) in a particular area, functioning together
  2. Self-supporting: contain everything they need to maintain themselves
    1. The only thing they need is an energy source
3. DISTRIBUTION
  1. When organisms are found in a particular area
  2. Investigated using LINE TRANSECTS
    1. 1) Mark a line and place quadrats next to each other along the line
      1. 2) Count & record organisms found in quadrats
        Percentage cover: estimating the % area of the quadrat covered by a particular organism
        Plot results in a kite diagram: map distribution of organisms in an area
  3. KITE DIAGRAMS
    1. Show abundance & distribution of organisms
      1. Abundance: shown by thickness of line
      2. X-axis: distance along transect line
4. ZONATION
  1. The gradual change in distribution of a species across a habitat
  2. A gradual change in abiotic factors can lead to zonation
5. BIODIVERSITY
  1. A measure of the variety of life in an area
  2. Ecosystems with a high level of biodiversity are healthier than those without
    1. Natural ecosystems
      1. Have a higher biodiversity & maintain themselves without any human interference eg native woodlands
    2. Artificial ecosystems
      1. Created & maintained by humans eg forestry plantations
  3. Includes:
    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
PHOTOSYNTHESIS
1. A two-stage process
  1. 1) Light energy is used to split water into oxygen gas & hydrogen ions
    1. 2) Carbon dioxide combines with hydrogen ions to make glucose & water
      1. BUT: Water is not one of the overall products ubecause more is used up than is produced
2. 6CO2 + 6H2O --> C6H12O6 + 6O2
3. Takes place in chloroplasts in plant cells
  1. Chloroplasts contain pigments - chlorophyll - that absorb light energy
4. USES OF GLUCOSE
  1. RESPIRATION
    1. Plants need glucose to respire so that they can release energy & convert glucose into various other useful things
  2. PROTEIN
    1. Glucose is combined with nitrates from soil to make amino acids for proteins - growth&repair
  3. CELL WALLS
    1. Converted into cellulose for making cell walls
  4. STORED AS STARCH
    1. Stored in roots, stems & leaves ready for use when photosynthesis is not happening - ie night.
      1. It is insoluble which makes it good for storing: it can't dissolve in water and move away from storage areas in solution. It doesn't affect the water concentration inside cells: soluble substances would bloat cells
  5. STORED IN SEEDS
    1. As lipids (fats/oils) eg sunflower seeds contain a lot of oil
5. DEVELOPMENT OF UNDERSTANDING
  1. Greek scientists 350BC
    1. Observed:the only thing touching plants was soil
      1. Concluded:plants gained mass from soil minerals
  2. Van Helmont 1648
    1. 1) Dried & weighed soil, put in pot
      1. 2) Planted willow tree weighing 2.2kg
        3) Added rainwater to pot whenever it was dry
        5 YEARS LATER...removed tree from pot - it weighed 76.7kg
        Dried & weighed soil: little change
        Tree must have gained mass from another source & from taking in water
  3. JOSEPH PRIESTLY 1770s
    1. 1) Candle in sealed container - went out & couldn't be relit while in there
      1. 2) Burning candle + living plant in container: flame went out but after a few weeks could be relit
        Candle used up something in container & plant 'restored the air' so candle could burn
    2. Exhaled air + mouse in sealed container = dead mouse (after a few secs)
      1. Exhaled air + plant + mouse in sealed container = living mouse (for several mins)
        Breathing had taken something out of the air - the plant 'restored the air' - allowed mouse to survive longer
    3. Plants restore something in the air that burning and breathing and air take out = OXYGEN
6. LIMITING FACTORS
  1. LIGHT
    1. Increased light = increased rate of photosynthesis
  2. CARBON DIOXIDE
    1. Increased light = increased CO2 = increased rate
  3. TEMPERATURE
    1. Photosynthesis works best warm but not too hot
      1. Increased temp = increased rate - but if temp too high, plant's enzymes denature
  4. As the graph flattens, the limiting reactant is no longer the limiting reactant, and it becomes on of the others
LEAVES & PHOTOSYNTHESIS
1. LEAVES ARE ADAPTED FOR DIFFUSION
  1. BROAD
    1. Large surface area for gases to diffuse
  2. THIN
    1. Water and CO2 only have to diffuse over a short distance
  3. STOMATA
    1. Let gases in&out & allow water to escape (transpiration)
  4. GUARD CELLS
    1. Surround each stoma and control gas exchange
  5. AIR SPACES & SPONGY MESOPHYLL
    1. Gases move between the stomata and photosynthesising cells - large S.A for gas exchange = big S.A : Vol ratio
2. LEAVES ARE ADAPTED TO ABSORB LIGHT
  1. BROAD
    1. Large S.A exposed to light
  2. CHLOROPLASTS
    1. Contain chlorophyll & other photosynthetic pigments to absorb light energy
  3. DIFFERENT PIGMENTS
    1. Each pigment absorbs different wavelengths of the sun's light - leaf can absorb as much light as poss
  4. CELLS CONTAINING MOST CHLOROPLASTS AT SURFACE OF LEAF
    1. Get the most light
  5. UPPER EPIDERMIS IS TRANSPARENT
    1. Light can pass through to the palisade layer

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BIOLOGY 4.0

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	Created by charl.mallon over 10 years ago