biology - topics

• Diffusion is the SPREADING OUT of particles from a HIGHER CONCENTRATION to a LOWER CONCENTRATION
• Diffusion happens in both gases and liquids
• The simplest case is when different gases diffuse through each other
• Diffusion occurs when particles move from a region of higher concentration to a region of lower concentration
• The bigger the concentration gradient (the difference in concentration), the faster the diffusion rate
• A higher temperature will give faster diffusion because the particles have more energy and move around faster
• Cell membranes

  They hold the cell together but let stuff in and out
• Dissolved substances can move in and out of cells by diffusion
• Only very small molecules can diffuse through cell membranes, like oxygen, glucose, amino acids
• Big molecules like starch and protein cannot fit through the cell membrane
• Particles flow through the cell membrane from where there's a higher concentration to where there's a lower concentration
• The larger the surface area of the membrane, the faster the diffusion rate, because more particles can pass through at once
• If a student adds a drop of ink to a glass of cold water, they will observe the ink gradually diffusing through the water
• If the ink is added to a glass of warm water, the diffusion will happen faster because the water particles have more energy and move around faster
• Active Transport


  A process, not defined
• Root Hairs

  • Take In Minerals and Water
• Root Hairs Take in Minerals Using Active Transport

  1. Minerals should move out of the root hairs if they and the nude of effusion.

  2. That method is, in fact, a conveniently mysterious process called "the".

  3. Active transport allows the plant to abeceb miners froees vary die sekon,

  4. concentration gradient. This is essential for its growth. But sove transport needs ROY

  5. from respiration to make it work.
• We Need Active Transport to Stop Us Starving

  • Active transport is used in the gut when there is a loser consentration of nutrients in the gat
  • but higher concentration of nutrients in the Mood
• • This means that glucose can be taken into the bloodstream when its concentration in the blood is already
  • higher than in the gut. It can then be transported to cells, where it's used for aspiration
• Active transport

  An important difference between active transport and diffusion is that active transport uses energy.
• Diffusion is the spreading out of particles from a higher concentration to a lower concentration
• Diffusion happens in both solutions and gases
• The fastest type of diffusion is when different gases diffuse through each other
• The bigger the concentration gradient (the difference in concentration), the faster the diffusion
• Particles move around faster when the concentration gradient is larger
• Cell membranes


  • They hold the cell together
  • Dissolved substances can move in and out of cells by diffusion
  • Only very small molecules can diffuse through all membranes (e.g. oxygen, glucose, amino acids, water)
  • Big molecules like starch and proteins can't fit through the membrane
• Particles flow through the cell membrane

  From where there's a higher concentration to where there's a lower concentration
• Particles move randomly in both directions through the cell membrane, but if there are a lot more particles on one side, there is a net movement towards the other side
• Larger surface area of the membrane

  Faster the diffusion rate
• Respiration


  Not "Breathing In and Out"
• Respiration Transfers Exergy for All Kinds of Things
• Respiration


  1. To build up (e.g. produce free acids)

  2. To move (e.g. to and fro)

  3. To keep things hot (about)
• Metabolism

  All the Chemical Reactions in an Organism
• Types of Respiration

  • Aerobic
  • Anaerobic
• Aerobic Respiration

  Many of these reactions happen together to form larger products
• Anaerobic Respiration

  1. Larger molecules are broken down into smaller ones

  2. Lots of small glucose molecules are joined together to form starch (a storage molecule in plant cells)

  3. Lipid molecules are each made from a long chain of fatty acids joined with glycerol to make triglycerides, which are then made into other lipids

  4. Larger molecules are broken down into smaller ones
• Respiration transfers energy to power all the reactions in the body for molecules
• Proteins broken down in digestion to produce amino acids. Urea is then excreted
• Metabolism

  The (total) of all of the chemical reactions that happen in a cell or the body
• Each individual living cell in your body is respiring every second of every day