B1

• How does digested food get from the gut to the blood?

  Villi
• What are villi

  Millions and millions of tiny projections in the small intestine
• What do villi do?

  Increase surface area so digested food is absorbed quicker into the blood
• Give 2 adaptions of the villi

  • single layer of surface cells for a short diffusion path
  • very good blood supply to assist quick absorption as it maintains concentration gradient
• What is the role of diffusion in cells?

  To take in needed substances and get rid of waste products
• How do you determine how easy it is for an organism to exchange substances with its environment?

  The ratio of surface area: volume
• How are exchange surfaces adapted to maximise effectiveness?

  • large surface area so lots of a substance can diffuse at once
  • thin membrane for shorter diffusion distance
  • animals have lots of blood vessels to get it in and out quickly
  • animals gas exchange surfaces are also ventilated so air moves in and out
• What is exchanging surfaces?

  How easily stuff moves between and organism and it’s environment
• What is the job of gas exchange in the lungs?

  To transfer oxygen into blood and remove waste carbon dioxide from it
• Where does gas exchange take place in the lungs?

  Alveoli
• How are alveoli specialised to maximise diffusion of oxygen and carbon dioxide?

  • enormous surface area
  • moist lining for dissolving gases
  • very thin walls
  • good blood supply
• State the components of a plant cell and their functions

  • nucleus to contain genetic information
  • mitochondria for respiration
  • ribosomes for protein synthesis
  • cytoplasm for chemical reactions
  • cell membrane to control what substances go in and out of cell
  • cell wall to strengthen the structure
  • chloroplast for photosynthesis
  • permanent vacuole contains cell sap
• State the function of a nerve cell

  To carry electrical signals from one part of the body to another
• How are nerve cells adapted to their function?

  • long branched connections to cover more distance
  • ends connect to form a network throughout the body
• State the function of a root hair cell

  Absorb water and minerals
• How are root hair cells adapted to their function?

  • grow long hairs that give it a large surface area for absorption from soil
• State the stages of the osmosis practical

  • cut 5 potato’s a similar size and length
  • measure the mass of each potato and put recordings into a table
  • measure 10cm3 of each concentration of sugar solution and place into boiling tubes
  • measure $10cm^3$of distilled water and place into the 5th boiling tube
  • add potato into each boiling tube and leave for a specific amount of time
  • take the potato’s out and blot them dry with paper rolls
  • measure the new mass of each potato and put into table
  • calculate the percentage change
• What is a light microscope?

  A microscope that uses visible light to magnify and observe individual cells and large subcellular structures
• What is an electron microscope?

  A microscope using electrons to see subcellular structures in more detail than light microscopes as they have a higher resolution and magnification
• Define resolution

  The ability to distinguish between two separate points
• What does a higher resolution mean?

  Sharper image
• What is the function of a xylem cell?

  Transportation of water and minerals in a plant
• How is a xylem cell adapted to its function?

  • Lignin in walls for strength and support
  • hollow in centre so water can flow through them
• What direction are water and minerals transported in a xylem cell?

  Upwards from the roots to the leaves
• state the function of a phloem cell

  Transport food substances produced by photosynthesis
• How are phloem cells adapted to their function?

  • Sieve tubes to connect channels for food substances to move throughout the plant
  • companion cells for energy
• What direction do substances move in a phloem cell?

  Upwards and downwards
• What is cell differentiation?

  Cell differentiation is the process by which cells become specialized in structure and function.
• state the function of a sperm cell

  Get the male DNA to the female DNA
• How are sperm cells specialised for their function?

  • streamlined head and long tail so it is able to swim to the egg
  • lots of mitochondria for energy when swimming
  • enzymes in head to digest through the egg cell membrane
• state the function of a muscle cell

  to contract quickly
• How is a muscle cell adapted to its function?

  • long so that they have space to contract
  • lots of mitochondria to generate energy needed for contraction
• What is diffusion?

  Diffusion is the movement of particles from an area of high concentration to an area of low concentration.
• What increases rate of diffusion?

  • A higher temperature
  • bigger concentration difference
• What is osmosis?


  The movement of water molecules from an area of high to low water concentration across a partially permeable membrane
• What is active transport?

  Active transport is the movement of particles against their concentration gradient, from an area of low to high concentration
• What does active transport require?

  Energy from respiration
• What the the two types of cells?

  • prokaryotic
  • eukaryotic
• What is the difference between a prokaryotic and eukaryotic cell?

  Prokaryotic cells lack a nucleus, while eukaryotic cells have a nucleus.
• Start an example of a prokaryotic cell

  Bacterial cell