Biology

• Environmental conditions vary depending on the biome. Different ecosystems and environment have different conditions for plants to survive
• Enzymes denature at temperatures greater than 40°C
• The rate of photosynthesis increases as the light intensity increases


  Because the rate depends on light intensity, it is called the limiting factor
• Plants need carbon dioxide to photosynthesise but there is only 0.04% in the atmosphere and is often the limiting factor controlling the rate of photosynthesis
• Over one day, light, temperature, and carbon dioxide levels change. Carbon dioxide may be the limiting factor when plants are crowded on a sunny day. Temperature may be the limiting factor in cooler months, light maybe it at dawn
• Carbon dioxide levels around plants rise when there is no light


  Plants are respiring but not photosynthesising, as light level increases, the plants use the carbon dioxide up
• Plants living in continual shade can adapt by having a higher ratio of leaves to root than other plants. The leaves are thinner, have a larger surface area and contain more chlorophyll to absorb light. A shortage of chlorophyll can limit the rate of photosynthesis
• In a forest, limited carbon dioxide means less growth and food for plants. In a tundra, limited light means it won't grow. In a desert, the heat would make the plant have less nutrition
• Environmental conditions in a forest would be more lively, have a large surface area and contain more chlorophyll in the plants. It would be more crowded there will be a limiting condition of carbon dioxide. A tundra would be more dry, and its limiting condition would be light as the plants are low to the ground and are small so it would get less light. In a desert, the limiting factor would be temperature as it is very hot in a desert
• Temperature, light, and carbon dioxide are the three limiting factors
• Limiting factor on a summer day would be too much light and temperature or reduced carbon dioxide levels
• Shade-tolerant plants are adapted to not need as much light, and rely more on other conditions to stay alive
• A tree having needles gives them more exposure to the sun which increases the rate of photosynthesis
• Cells

  • Sperm cell
  • Nerve cell
  • Root hair cell
  • Hen's egg
• Plants photosynthesise to grow, gain nutrients so they can grow and feed themselves
• If there is a warning that says: ‘Irritating to eyes, respiratory system and skin’, you need to wear gloves and protective glasses to prevent the acid from touching your skin
• The equation for aerobic respiration is: C6 H12 O6 + 6 O2 -> 6CO2+6H2O (+energy)
• The symbol equation for photosynthesis is CO2+H2O -> C6H12O6+O2
• Chloroplasts absorb energy from sunlight
• Food tests

  1. Test for starch

  2. Test for glucose

  3. Test for protein

  4. Test for lipids
• Respiration

  1. Aerobic

  2. Anaerobic
• To balance the equation for photosynthesis, all components need to be multiplied by 6: 6CO2+6H2O -> C6H12O6+6O2
• Aerobic respiration occurs in mitochondria, same in plants and animals: Glucose + oxygen -> carbon dioxide + water
• Anaerobic respiration occurs in the cytoplasm, different in plants and animals: Animals produce lactic acid, plants and yeast produce ethanol + water + carbon dioxide
• Diffusion and Osmosis

  Friday 9th February 2024
• Respiration - Anaerobic


  Different in plants and animals, happens in cytoplasm, plant and yeast: glucose -> lactic acid, animals: glucose -> lactic acid, plants and yeast: glucose -> ethanol + water + carbon dioxide
• Factors affecting rate of respiration

  Increase of temperature, increase of oxygen concentration, enzymes involved in respiration denature after 40°C
• Exercise increases breathing rate, breathing depth, heart rate, and body performs anaerobic respiration leading to increased lactic acid production
• Respiration - Aerobic


  In mitochondria, same in plants and animals, glucose + oxygen -> carbon dioxide + water
• Anaerobic respiration in animals

  Glucose + lactic acid
• Photosynthesis

  6CO2 + 6H2O -> C6H12O6 + 6O2
• Differences between light and electron microscope

  • Light: cheap, see in colour
  • Electron: expensive, black and white
• Anaerobic respiration in yeast

  Glucose + carbon dioxide + ethanol
• Factors affecting rate of diffusion

  Concentration gradient, concentration, mass of diffusing molecules, temperature
• Net movement of particles from high to low concentration, down a concentration gradient, diffusion is a passive process
• Diffusion


  The movement of molecules from an area of high to low concentration
• Diffusion works fastest at 62 degrees Celsius and slowest at -23 degrees Celsius
• Water potential

  The tendency of water to move from an area of high water potential to an area of low water potential
• Osmosis is the diffusion of water molecules through a partially permeable membrane from high to low water concentration
• Lower solute concentration

  High water concentration, high water potential, dilute solution