Chapter 1

• What is the function of the cytoplasm?

  Chemical reactions take place here
• What is the function of the cell membrane?

  The cell membrane regulates what enters and leaves the cell
• What is the function of the cell wall?

  A rigid layer that supports the cell and provides shape, made of cellulose for strength.
• What is the function of the chloroplasts?

  Contains chlorophyll which absorbs light energy for photosynthesis
• What is the function of the vacuole?

  Filled with cell sap to keep the cell rigid
• What is the function of the nucleus?

  Contains the cell's genetic material
• What is the function of the ribosome?

  The site of protein synthesis
• What is the function of the mitochondria?

  The site of respiration
• What are the differences between prokaryotic cells and eukaryotic cells?

  Prokaryotic cells don't have a nucleus or mitochondria but they do have plasmids, flagella and genetic material
• How is a sperm cell specialised?

  Long tail and streamlined head to help reach the egg, as well as lots of mitochondria to release energy
• How is a nerve cell specialised?

  They have lots of branches to make connections with other cells
• How is a muscle cell specialised?

  They have lots of mitochondria to transfer the energy needed for chemical reactions. They also store glycogen that can be used in cellular respiration
• How is a root hair cell specialised?

  They have an extension to increase the surface area for absorbing water and minerals

  They have a large permanent vacuole that speeds up the movement of water by osmosis from the soil to the cell

  They have mitochondria that transfer energy needed for the active transport of minerals into the cell
• How is a plant cell (leaf palisade cell) specialised?

  They contain chloroplasts containing chlorophyl for maximum photosynthesis

  They have a large permanent vacuole that helps keep the cell rigid as a result of osmosis
• What does a plant cell have that an animal cell doesn't have?

  A cell wall, chloroplasts and a vacuole
• What are the parts of a microscope?

  Fine focussing wheel, coarse focussing wheel, eye piece lens, objective lens, slide, stage, mirror/lamp

  
• What is an advantage of using an electron microscope compared to a light microscope?

  Electron microscope has a greater magnification than a light microscope
• What is the order of these units?

  Nanometres, micrometres, millimetres, centimetres, metres
• What is the equation to work out magnification?

  Magnification = image size / real size

  
• What is resolution? Why is high resolution good?

  Resolution is the ability to distinguish between 2 points. High resolution is good as it means that the image is sharp and detailed.
• Describe how to make a slide of plant tissue (onion)


  1)Carefully peel back a layer of onion with tweezers

  2)Place the onion on the slide as flat as possible

  3)Put two drops of iodine on top of the onion to create an iodine stain

  4)Place the coverslip over the top using a mounted needle to prevent bubbles being trapped underneath
• What are some rules about drawing what you see under a microscope?

  -Use a sharp pencil

  -No shading or colouring

  -Write a title and what magnification you used

  -Label important features using straight lines.
• What is the definition of diffusion?

  The movement of particles from an area of high concentration to an area of low concentration down a concentration gradient
• What factors affect the rate of diffusion?

  Temperature- an increase in heat energy mean and increase in kinetic energy of particles

  Surface area- more area for diffusion

  Concentration gradient- The steeper the concentration gradient the faster diffusion takes place
• What is the definition of osmosis?

  Osmosis is the diffusion of water. It is the movement of water molecules from a higher water concentration to a lower water concentration, through a partially permeable membrane.
• How is active transport different from diffusion?

  Active transport requires energy to move particles against the concentration gradient.
• Where does active transport occur in a plant?

  Minerals enter a root cell by active transport. The plant uses energy to move minerals up the concentration gradient from the soil into its cells
• Where does active transport occur in an animal?

  The villi in the small intestine uses active transport to continue the transport of the small amounts of remaining nutrients against the concentration gradient
• What does osmosis look like in plant and animal cells?

  
• What's the method for the osmosis required practical?

  1)Prepare 5 glucose solutions of varying concentrations

  2)Cut potato chips to same length

  3)Weigh chips, record mass

  4)Place in solution for 12 hours

  5)Reweigh

  6)Calculate percentage change in mass (allows comparison)

  7)Draw graph of results
• What is the independent variable?

  The concentration of glucose solution
• What is a dependent variable?


  Percentage change in mass of chip
• What are the controlled variables?

  Volume of solution, temperature, time, same size chip
• Name two sources of error with the practical

  If you don't dry the potatoes before reweighing they might have solution on them which

  makes them heavier so pat dry them before

  reweighing

  Water may evaporate from the solutions in

  the tubes, making them more concentrated

  Put a bung in the tubes

  Error can also be avoided by repeating the experiment and calculating the mean