biology paper 1

• What is the focus of the AQA GCSE Biology paper 1?

  Cells, organization, infection and response, and bioenergetics
• What is the difference between eukaryotic and prokaryotic cells?

  Eukaryotic cells have a nucleus, while prokaryotic cells do not
• What structures can be seen with a light microscope?

  Cells and possibly the nucleus
• What advantage does an electron microscope have over a light microscope?

  It allows us to see finer details of organelles
• How can you calculate the actual size of a cell using a microscope?

  By dividing the image size by the magnification
• What is the function of the cell membrane?

  It keeps everything inside the cell and is semi-permeable
• What is the composition of the cell wall in plant cells?

  Cellulose
• What is the role of mitochondria in a cell?

  It is where respiration takes place, releasing energy
• What do ribosomes do in a cell?

  They assemble or synthesize proteins
• What is the function of chloroplasts in plant cells?

  They contain chlorophyll and are where photosynthesis takes place
• What is a permanent vacuole in plant cells used for?

  Storing sap
• How do bacteria multiply?

  By binary fission
• What is the procedure for culturing bacteria on agar using aseptic technique?

  • Lift the lid of the dish towards a flame to move microbes away
  • Use sterilized equipment to place bacteria culture on agar
  • Tape the lid partially to allow air in
  • Incubate at 25°C
• How do you calculate the area of a circle in a bacterial culture?

  Using the formula $A =$$\frac{\pi d^2}{4}$
• How many pairs of chromosomes do humans have?

  23 pairs
• What are diploid cells?

  Cells that have two sets of chromosomes
• What are gametes and how many chromosomes do they have?

  Gametes have 23 chromosomes, which is half of the diploid number
• What is the process of mitosis?

  It is the duplication of genetic material to form two identical cells
• Where are stem cells found in humans?

  In embryos and bone marrow
• What are stem cells?

  Cells that have not yet specialized
• How can stem cells be used in medicine?

  To combat conditions like diabetes and paralysis
• What is diffusion?

  The movement of molecules from high to low concentration
• What is osmosis?

  The diffusion of water across a semi-permeable membrane
• How can the rate of diffusion be increased?

  By increasing concentration difference, temperature, or surface area
• What is the practical procedure for investigating osmosis using potato cylinders?

  1. Cut equal-sized potato cylinders and weigh them
  2. Place in test tubes with varying sugar concentrations
  3. After a day, remove and weigh again
  4. Calculate percentage change in mass
  5. Plot results against sugar concentration
• What is active transport?

  Movement of substances against a concentration gradient using energy
• What is a tissue?

  A group of similar cells working together
• What is an organ?

  A structure made of different tissues working together
• What is an organ system?

  A group of organs working together
• What is the role of bile in digestion?

  It neutralizes stomach acid and emulsifies fats
• What are enzymes?

  Biological catalysts that speed up chemical reactions
• What is the lock and key principle in enzyme activity?

  Enzymes are specific and only work with certain substrates
• What happens to an enzyme at its optimum temperature?

  The rate of enzyme activity is maximized
• What is denaturation in enzymes?

  When the active site changes shape and the substrate can no longer bind
• What is the practical procedure for investigating enzyme activity with amylase and starch?

  1. Mix amylase with starch at different temperatures or pH levels
  2. Time how long it takes for starch to be broken down
  3. Use iodine to test for starch presence
  4. Plot results against temperature or pH
• What color does iodine turn in the presence of starch?

  Black
• What color does Benedict's solution turn in the presence of sugars?

  Orange
• What color does Biuret's reagent turn in the presence of proteins?

  Purple
• What happens to cold ethanol in the presence of lipids?

  It turns cloudy
• What is the role of the respiratory system?

  To provide oxygen for respiration and remove carbon dioxide