Movement in and out of cells

• Diffusion is the net movement of particles from an area of high concentration to an area of low concentration
• Net movement is the movement of all of the particles considered together as a group
• Diffusion can happen in both gases and liquids
• Cell membranes are partially permeable
• Partially permeable means that some substances will pass through while others won't
• Molecules that can diffuse through a cell membrane are usually small molecules such as water molecules, glucose molecules, and amino acids
• Large molecules that don't pass through a partially permeable cell membrane are protein and starch molecules
• Diffusion is a passive process
• Factors that affect diffusion are the concentration gradient, surface area, and temperature
• The larger the concentration gradient the higher the rate of diffusion
• Temperature affects diffusion by increasing the kinetic energy of particles which makes them move faster so they collide with the membrane more often
• Higher temperature means higher the rate of diffusion
• Larger surface area means higher rate of diffusion
• Osmosis is the net movement of water molecules from a region of high water concentration to a region of low water concentration across a partially permeable membrane
• Dissolved molecules are solutes
• When a beaker has more solute molecules it will have a higher concentration of solutes than the solvent
• Proportion of water: Solutes determines concentration of water in the solution. Volume of water does not matter
• Inside our cells we have lots of water particles and a fair few solute particles. Outside our cells we have almost pure water with only very few solute particles
• Less solutes= Higher water concentration
• Active transport is the movement of molecules across a membrane from an area of low concentration to an area of high concentration against a concentration gradient
• Passive transport is the movement of molecules down their concentration gradient, no energy required
• Active transport requires energy from the cell
• Active transport always takes place across a membrane
• Energy for active transport comes from cellular respiration
• Cellular respiration happens mainly in the mitochondria when they break down glucose to release energy
• The process of cellular respiration is responsible for all the energy that the cell uses
• ATP is a molecule that is used to store energy in cells
• ATP acts like a rechargeable battery. Cells generate ATP through processes like cellular respiration.
• Plants need mineral ions and water to survive and grow. They absorb this from the soil of a plant.
• Root hair cells are specialised cells found on roots which have many extensions called root hairs, these increase surface area so more minerals can be absorbed into the plant.
• Minerals that plants need are at a higher concentration inside the root hair cell and at a lower concentration outside in the soil, so the roots have to use energy to absorb the minerals by active transport against their concentration gradient
• Active transport requires energy because it goes against the concentration gradient
• The energy for the process of active transport comes from cellular respiration
• An adaptation of root hair cells is they have lots of micthochondria to absorb water and minerals