Science

• Anaerobic respiration takes place when there isn't enough oxygen to carry out aerobic respiration. This happens during intense exercise or if someone has been drowning underwater for too long.
• Respiration releases energy.
• The equation for aerobic respiration is Glucose + Oxygen -> Carbon dioxide + Water (+ Energy)
• Complete combustion produces water vapour and carbon dioxide.
• Incomplete combustion produces carbon monoxide, soot and sulphur oxides.
• The equation for anaerobic respiration is Glucose --> Lactic Acid (+ energy)
• Respiration occurs in the mitochondria of the cell.
• Four things that are needed for the plant to photosynthesize:

  1. Sunlight
  2. Chlorophyll
  3. Carbon dioxide
  4. Water
• Chloroplasts contain chlorophyll which absorbs light energy from sunlight
• Water evaporates into air through stomata on leaves
• If oxygen is present, it will relight a glowing splint.
• Gases such as oxygen and carbon dioxide can travel through tiny holes underneath the leaf called stomata. 
• Photosynthesis is a chemical process in plants where the energy in light is stored in glucose, occurring in the chloroplasts and using chlorophyll to absorb light
• Glucose produced in photosynthesis is used by plants for growth and to make other substances like cellulose and starch
• Respiration in plants is a chemical reaction in the mitochondria where glucose and oxygen react to produce carbon dioxide and water, releasing energy
• Plants respire all the time, but only photosynthesize when in the light; during photosynthesis, carbon dioxide diffuses into the leaf through stomata, and oxygen and water vapor leave the leaf
• Factors affecting the rate of photosynthesis include light intensity, levels of carbon dioxide, presence of chlorophyll, water, and temperature
• Photosynthesis takes place inside specialised cells called chloroplasts.
• Photosynthesis:

  Carbon dioxide + water -> glucose + oxygen
• Carbon dioxide is needed for photosynthesis to take place in plants and is also produced when plants respire.
• • During the day carbon dioxide diffuses into the leaf through the stomata which is needed for photosynthesis.
• • When cells in the leaf photosynthesise during the day, they will produce the oxygen needed for the plant to respire, therefore more oxygen is not required to diffuse into the leaf from the air.
• At night, there is no sunlight so photosynthesis cannot occur. The plant needs oxygen to respire as it does not have enough stored up. Therefore, oxygen must be taken in by diffusion from the air.
• If the light intensity increases then the rate of photosynthesis will increase too.
• The amount of chlorophyll present affects how much light energy can be absorbed by the leaves.
• Static electricity

  1. Objects can become positively charged or negatively charged, usually because of friction between insulators

  2. Charged objects exert electrostatic forces on each other, which can be attractive or repulsive

  3. Charged objects can attract neutral objects due to the polarisation of charge
• Insulator


  • A material that does not allow current to flow through it easily, e.g., wood or glass
• Atom

  • Consists of a positively charged nucleus surrounded by negatively charged electrons. Normally, the positive and negative charges cancel out, making the atom neutral
• Opposite charges


  Attract each other
• Like charges


  Repel each other
• Discharging a charged object


  By giving it a way to drain its electrons into the ground, the charge can be released, often resulting in a spark
• An electric shock can happen when a person approaches a metal object or another person due to static electricity
• Static electricity

  Build-up of electrical charge on an object, which can be either positive or negative
• Effects of static electricity

  • Sparks, making a balloon stick to a wall, attracting hair
• Electrostatic forces


  Forces between two electrically charged objects, can be attractive or repulsive
• Electrostatic forces can cause objects to levitate
• Static electricity can make your hair stand on end
• Oppositely charged insulators can attract
• Experiment 1

  Rub a balloon on your hair to make it positively charged and the balloon negatively charged, then observe attraction
• Neutral objects are sometimes attracted by electrostatic forces too