biology

• What is the difference between eukaryotic and prokaryotic cells?

  Eukaryotic cells have a nucleus, while prokaryotic cells do not
• What structures are visible 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 do ribosomes do in a cell?

  They assemble or synthesize proteins
• What is the composition of the cell wall in plant cells?

  Cellulose
• What is the function of chloroplasts in plant cells?

  They contain chlorophyll and are where photosynthesis takes place
• How do bacteria multiply?

  By binary fission
• What is the role of mitochondria in a cell?

  It is where respiration takes place, releasing energy
• What is a permanent vacuole in plant cells used for?

  It stores sap
• 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}$
• What is the difference between diploid and haploid cells?

  Diploid cells have 23 pairs of chromosomes, while haploid cells have 23 single chromosomes
• How many pairs of chromosomes do humans have?

  23 pairs
• What is the process of mitosis?

  It is the duplication of genetic material and division into two identical cells
• Where are stem cells found in humans?

  In human and animal embryos and bone marrow
• What ethical considerations are associated with cloning and stem cell research?

  Cloning raises ethical concerns about identity and the implications of creating life
• What are the potential uses of stem cells?

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

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

  It 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 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?

  It is the movement of substances against a concentration gradient using energy
• What is the role of tissues in the body?

  Tissues are groups of similar cells that perform a specific function
• What is an organ?

  An organ is a structure made up of different tissues working together
• What is the function of the digestive system?

  It breaks down food into useful nutrients
• What does bile do?

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

  Biological catalysts that speed up chemical reactions
• What is amylase?

  An enzyme that breaks down starch into glucose
• What is the lock and key principle in enzyme activity?

  It describes how substrates fit into an enzyme's active site
• What happens to an enzyme when it denatures?

  The active site changes shape, preventing substrate binding
• How does temperature affect enzyme activity?

  Increased temperature increases activity until denaturation occurs
• What is the food test for starch?

  Iodine turns from brown to black in the presence of starch
• How do you determine the optimum temperature or pH for an enzyme?

  By plotting the time taken for a reaction against temperature or pH
• What is the role of the respiratory system?

  To provide oxygen for respiration and remove carbon dioxide
• What is the pathway of air during breathing?

  Trachea, bronchi, bronchioles, alveoli
• What happens in the alveoli during gas exchange?

  Oxygen diffuses into the blood, and carbon dioxide diffuses out
• What is the function of hemoglobin?

  To bind oxygen in red blood cells
• What is the structure of the heart?

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