Biology p1

• 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 advantage does an electron microscope have over a light microscope?

  It allows us to see finer details of organelles
• What structures can be seen with a light microscope?

  Cells and possibly the nucleus
• How can you calculate the actual size of a cell using a microscope's magnification?

  Actual size = image size / magnification
• What is the role of mitochondria in a cell?

  Mitochondria are where respiration takes place, releasing energy
• What do ribosomes do in a cell?

  Ribosomes are where proteins are assembled
• What is the function of the cell membrane?

  It keeps everything inside the cell and is semi-permeable
• What is the purpose of a permanent vacuole in plant cells?

  It stores sap
• What is the function of chloroplasts in plant cells?

  Chloroplasts contain chlorophyll and are where photosynthesis occurs
• How do bacteria multiply?

  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 bacterial culture?

  Area = $\frac{\pi d^2}{4}$
• What is the difference between diploid and haploid cells?

  Diploid cells have 46 chromosomes, while haploid cells have 23
• What is the chromosome number in human diploid cells?

  46 chromosomes (23 pairs)
• What is the process of mitosis?

  Mitosis is the process where genetic material is duplicated and divided into two identical cells
• What are stem cells?

  Stem cells are undifferentiated cells that can specialize into different cell types
• What is diffusion?

  Diffusion is the movement of molecules from high to low concentration
• How can stem cells be used in medicine?

  They can be used to treat conditions like diabetes and paralysis
• What is osmosis?

  Osmosis is 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 active transport?

  Active transport is the movement of substances against a concentration gradient using energy
• What is the practical procedure for investigating osmosis using potato cylinders?

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

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

  An organ is made up of different tissues working together
• What is the function of bile?

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

  Enzymes are biological catalysts that speed up chemical reactions
• What happens to an enzyme when it denatures?

  The active site changes shape, preventing substrate binding
• What is the lock and key principle in enzyme activity?

  It describes how substrates fit into an enzyme's active site
• How do you determine the optimum temperature for enzyme activity?

  By plotting time taken for reaction against temperature
• 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?

  It provides oxygen for respiration and removes carbon dioxide
• What is the pathway of air during breathing?

  Trachea → bronchi → bronchioles → alveoli
• How does oxygen enter the blood from the alveoli?

  Oxygen diffuses into the blood vessels surrounding the alveoli
• What is the function of hemoglobin in red blood cells?

  Hemoglobin binds to oxygen for transport
• What is the role of valves in the heart?

  Valves prevent backflow of blood
• What is the structure of the heart?

  The heart has four chambers: right atrium, right ventricle, left atrium, left ventricle