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• Nitrate


  Needed to help the plant convert carbohydrates into proteins, so the plant can grow
• All organisms need protein for growth
• It can be difficult even for an expert to tell the difference between a plant that is short of magnesium and one that is short of protein
• Photosynthesis


  • Happens inside chloroplasts, which are inside some of the cells in a leaf
  • Carbon dioxide diffuses into the leaf from the air
  • The tiny holes in the leaf which allow gases to diffuse in and out are called stomata
  • The spongy mesophyll are the cells in the leaf that do a small amount of photosynthesis
• Root hair cells


  • Provide a really big surface through which water and mineral ions can be absorbed
  • Water and mineral ions (magnesium and nitrate) move into root hair cells from the soil / along the water
• Xylem vessels


  The pathway that takes water and mineral ions from the plant to the leaf
• Phloem vessels


  The pathway that takes sucrose from the leaves to every part of the plant
• Transpiration


  The loss of water vapours from the leaves
• Stomata


  • Located on the underside of the leaf, so it's not directly exposed to the sun, which reduces excessive water loss
• Water


  • Helps the plant stand upright
  • A plant cell that has plenty of water is strong and firm
  • When a plant cell doesn't contain enough water, it becomes soft and floppy, causing the plant to collapse or wilt
  • Transports dissolved mineral salts from the roots to all the other parts of the plant
  • One of the reactants in photosynthesis
  • When it evaporates, it takes heat away and cools the cell
• Protein


  Made up of amino acids
• Carbohydrates


  The final products are glucose, galactose and fructose
• Fats and oils


  Triglycerides, glycerol and fatty acids
• Excretion


  The removal of waste products from the body that have been inside the body
• Substances excreted


  • Carbon dioxide - made in respiration
  • Urea - a waste substance made in liver cells
• Excretion process


  1. The kidneys filter the blood to remove urea

  2. The urea dissolves in the excess water, forming urine

  3. The urine flows down the ureter to the bladder, which can store it for a while

  4. The urine flows out of the body from the bladder through the urethra
• Fetus


  • A baby before it is born
  • Relies on the mother for food supply and the removal of substances it needs to excrete
  • The mother's blood and the fetus's blood don't mix, but substances can diffuse between them
• Substances needed by the fetus

  • Protein - helps produce new cells and grow
  • Carbohydrate - supplies energy
  • Vitamins and minerals - iron needed to make haemoglobin, calcium essential for strong bones and teeth
• Smoking cigarettes


  Carbon monoxide in the blood reduces the amount of oxygen that haemoglobin can transport, affecting the development of the fetus
• Drug


  Something taken into the body that affects the way the body works
• Desert plants


  • Store water in their leaves, stems and roots
  • Have a thick waxy layer that helps prevent water loss
  • Have small leaves that help reduce evaporation
  • Have deep taproots that help them reach underground water sources
• Carbon cycle


  1. Photosynthesis - plants take in carbon dioxide and use it to make carbohydrates

  2. Feeding - animals and humans eat carbon-containing nutrients from plants and other animals

  3. Decomposition - decomposers get carbon from breaking down waste products

  4. Respiration - humans and animals release carbon dioxide when they breathe out

  5. Combustion - burning fossil fuels releases carbon dioxide into the air
• Carbon dioxide and methane are greenhouse gases
• Climate


  The long-term pattern of temperatures, wind and rainfall on Earth
• The Earth has cycled between relatively warm periods and relatively cold ones for billions of years
• In the warm periods, there was no ice at all, even at the poles. In the colder periods, called ice ages, there was ice at the poles.
• 650 million years ago, two asteroids collided with one another when they were in space, somewhere in between Earth and Mars.
• The collisions produced huge quantities of dust. The dust reduced the amount of light and heat from the Sun reaching the Earth's surface. This triggered an ice age.
• Asteroids colliding with Earth created massive tsunamis and huge quantities of rock and dust into the air.
• Dust in the air meant that less light reached the Earth's surface. Plants could not photosynthesise, so animals had less food. This led to disruption of food chains and mass extinction.
• Meteoroids


  Objects in space that are smaller than an asteroid
• Meteors


  Meteoroids that enter the Earth's atmosphere
• Meteorites


  The parts of meteoroids that do collide with Earth
• When assessing the possible risk to Earth, scientists look at the mass or diameter of the asteroid and its closest possible approach to Earth. An asteroid passing further from Earth may be a greater risk than one passing closer if its mass is greater.
• Impacts of climate change include rise in sea levels, difficulty predicting rainfall, and more extreme weather events.
• Group I - Alkali metals


  • Lithium, Li
  • Sodium, Na
  • Potassium, K
• Group I metals


  • Atomic number and mass number increase as you go down the group
  • Melting and boiling point decrease as you go down the group
• Lithium


  Atomic number 3, mass number 7, 3 protons, 3 electrons, 4 neutrons
• Sodium


  Atomic number 11, mass number 23, 11 protons, 11 electrons, 12 neutrons
• Potassium


  Atomic number 19, mass number 39, 19 protons, 19 electrons, 20 neutrons