Integrated Science

• States of matter

  • Solid
  • Liquid
  • Gas
• Characteristics of a Solid


  • Fixed shape; incompressible
• Characteristics of a Liquid


  • No fixed shape; can flow; very difficult to compress
• Characteristics of a Gas


  • No fixed shape; spreads out to fill its container; easily compressed
• Particle theory

  Also known as the kinetic theory of matter, describes:

  • The movement of particles
  • The average distance between particles within each state of matter
• How are particles arranged in each state of matter?

  • Solid: Particles are touching in a regular pattern
  • Liquid: Particles are touching in an irregular, random arrangement
  • Gas: Particles have large distances between them in an irregular, random arrangement
• How do particles move in each state of matter?

  • Solid: Vibrate on the spot
  • Liquid: Slip and slide over and around each other
  • Gas: Can move very quickly in a random manner between collisions
• Average distance between particles in each state of matter

  • Solid: Most particles are touching
  • Liquid: Most particles are touching
  • Gas: Large distances
• Changing state of matter

  1. Solid to liquid: At melting point, particles break free from neighbours

  2. Liquid to gas: At boiling point, more particles gain enough energy to escape from surface

  3. Solid to gas (sublimation): Solid changes directly to gas without passing through liquid phase
• Each change of state is reversible and is an example of a physical change, no new substances are formed
• Substances with higher melting points and boiling points have stronger forces of attraction between their particles
• Some people classify a fourth state of matter called plasma
• Changes of state of matter

  • Liquid to solid (freezing)
  • Gas to liquid (condensation)
  • Solid to liquid (melting)
  • Liquid to gas (boiling)
  • Solid to gas (sublimation)
• Melting point

  The temperature at which a solid turns into a liquid
• Boiling point

  The temperature at which a liquid turns into a gas
• As a solid is heated

  The particles vibrate faster until they break free from their neighbours and the solid melts
• As a liquid is heated

  More particles gain enough energy to escape from the surface, increasing the rate of evaporation until the liquid boils
• Boiling water in a kettle is an everyday 'change of state'
• Key points

  • The three states of matter are solids, liquids and gases
  • The particles in a solid are packed closely together, fixed in their positions and vibrate
  • The particles in a liquid are also close together, but can slip and slide over each other in a random motion
  • The particles in a gas have, on average, lots of space between them and zoom around randomly
• Learning outcomes

  • List the states of matter
  • Describe the properties of solids, liquids and gases
  • Explain the properties of each state of matter using particle theory
• All living things are made up of cells, which are essential for all life on Earth
• Animal cell contain

  A nucleus, cell membrane, cytoplasm and mitochondria
• Plant cell contain

  A cell wall, chloroplasts and a vacuole in addition to the components of an animal cell
• Functions of cell parts

  • Nucleus: Control centre that controls cell activities and contains genetic material
  • Cell membrane: Outer barrier that allows some substances to pass in and out
  • Cytoplasm: Jelly-like liquid where chemical reactions occur
  • Mitochondria: Sites of respiration
  • Ribosomes: Where proteins are made
  • Cell wall: Provides support and shape (plant cells only)
  • Chloroplasts: Sites of photosynthesis (plant cells only)
  • Vacuole: Large central part filled with cell sap to support the plant (plant cells only)
• Chromosomes carry genetic information in the form of DNA
• Learning outcomes

  • List the parts that make up an animal cell and those that make up a plant cell
  • Draw a labelled diagram of a typical unspecialised animal cell and plant cell
  • Explain the functions of the main parts of a cell
• Diffusion and osmosis are vital processes in the transport of substances into and out of cells
• Diffusion


  The movement of particles (molecules or ions) from an area of high concentration to an area of low concentration
• Diffusion occurs


  When particles are not distributed evenly
• Osmosis


  The movement of water molecules across a partially permeable membrane, from a dilute solution with a high concentration of water to a concentrated solution with a low concentration of water
• The cell membrane is partially permeable in osmosis, allowing only certain substances to pass through
• Learning outcomes

  • Explain the processes of diffusion and osmosis
  • Illustrate the movement of particles (molecules or ions) in and out of cells
  • State that the cell membrane is partially permeable in osmosis
• Glucose solution

  Concentrated solution inside the sealed partially permeable bag
• Osmosis experiment

  1. Bag put in beaker of water

  2. Bag swells up

  3. Water moves across partially permeable membrane into concentrated glucose solution

  4. Water moves from region of high concentration (pure water) to region of low concentration (concentrated glucose solution)
• Diffusion and osmosis

  • Vital processes in the transport of substances into and out of cells
  • Involve the transfer of particles down a concentration gradient
• Diffusion

  Movement of particles from an area of high concentration to an area of low concentration
• Osmosis

  Movement of water molecules across a partially permeable membrane - from a dilute solution with high water concentration to a concentrated solution with low water concentration
• Active transport

  • Moves substances into, out of, or between cells against a concentration gradient
  • Requires special transport proteins in cell membranes
  • Requires energy from respiration
• Where active transport is needed

  • To move mineral ions into root hair cells
  • To move glucose out of kidney cells when blood sugar is low
  • To move ions in and out of cells to maintain balance
• Asexual reproduction

  • Only one parent needed
  • Cells divide to form identical offspring (clones)