B4 | Mindmap

Photosynthesis and Respiration
1. Photosynthesis - Process where plants make their own food
2. Respiration is the process by which all organisms release energy from food
Enzymes
1. Chemicals that speed up the rate of chemical reactions
2. Enzymes are proteins. They are long chains of amino acids
3. The chemicals that enzymes work on are called substrates
4. Active site - special shape to fit certain substrates - Like key and lock
5. After enzymes react their substrates product molecules are released
6. Enzymes need a specific pH and temperature to work at their optimum
7. They stop working if the pH is inappropriate or the temperature is too high
8. 37 degrees is the most common optimum for mammals enzymes
9. As the temperature increases, enzyme activity increases as temperature increases rate of reaction
10. High temperatures or unsuitable pH can denature an enzyme / change the shape of its active site
Glucose
1. Photosynthesis happens in plant cells and in some microorganisms such as phytoplankton
2. Sunlight is absorbed by the green chlorophyll which are found in chloroplasts
3. Uses
  1. Converted to chemicals needed for the plants growth
  2. Converted into starch for storage
  3. Used in respiration
4. 6 CO2 + 6 H2O --> C6H12O6 + 6 O2
Cells
1. Surrounded by cell membrane, which controls what enters and leaves the cell
2. Animals
  1. Nucleus - cytoplasm - cell membrane - mitochondria
3. Plants
  1. Nucleus - cytoplasm - cell membrane - mitochondria - cell wall
4. Microorganisms
  1. Cytoplasm - Cell membrane - Cell wall
  2. Bacteria cells have no nucleus
  3. Yeast have mitochondria - bacteria dont
Transport of chemicals
1. Diffusion
  1. Movement of chemicals from high to low concentrations
  2. In photosynthesis
    1. Water is taken up by plant roots by diffusion
    2. CO2 diffuses through plant leaves
    3. Oxygen leaves plants by diffusion
  3. Its passive - doesnt require any energy as it happens by random molecule movement
2. Osmosis
  1. Special kind of diffusion involving water
  2. Happens when chemicals are separated by a semi-permeable membrane
  3. Overall movement of water from an area of high concentration to low concentration
  4. Movement of water into roots
3. Active transport
  1. Nitrates are normally in higher concentrations in plants so they can't use diffusion
  2. Active transport uses energy from respiration to transport chemicals across a cell membrane
Factors with photosynthesis
1. Can be limited by CO2, light intensity and temperature
2. If light intensity or CO2 levels are increased the rate of photosynthesis increases and then levels off
3. At the point the graph levels out something is limiting it, this is called the limiting factor
4. As temperature increases the rate increases up to a certain point and then decreases due to denaturing of enzymes
Investigation
1. Use an identification key / survey to identify plants - measure how common they are - use a light meter to measure intensity
2. Ecologists investigate the abundance and distribution of plants - at different locations and in different areas
3. A quadrat (wooden frame) is used to sample an area
  1. It is thrown randomly - a number of times so that an average is taken
4. If there is an obvious change in the plants in the area use the quadrat in a line called a transect
5. Trees and stuff provide shade and can often affect the growth of plants
6. May be a correlation between the distance from a tree or something and the growth of nearby plants at high or low densities
Respiration
1. Aerobic
  1. glucose + oxygen --> carbon dioxide + water (energy released)
  2. C6H12O6 + 6 O2 -> 6 CO2 + 6 H20
  3. Only done when organism has enough oxygen
  4. It is done by a series of enzyme reactions
2. Occurs in every cell in the body
3. Anaerobic
  1. When oxygen is low
  2. glucose -> lactic acid (energy)
  3. C6H12O6 --> 2 C3H6O3
  4. Done in animal muscle cells during vigorous exercise - plant roots in waterlogged soil - bacteria in deep puncture wounds
4. Fermentation
  1. Type of anaerobic respiration used by some microorganisms
  2. Yeast and some plants do this
  3. glucose --> ethanol + CO2 (energy)
  4. Ethanol is alcohol so it is useful for us
  5. Bubbles of CO2 make bread rise and alcoholic drinks sparkle
  6. In bread alcohol is evaporated as it is cooked

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B4

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