Topic B1 - Cell biology

• What are the two main types of organisms based on cell structure?

  Prokaryotes and Eukaryotes
• What is the main difference between prokaryotic and eukaryotic cells?

  Eukaryotic cells are complex and larger, while prokaryotic cells are smaller and simpler
• What type of cells do eukaryotes consist of?

  Eukaryotic cells
• What is a prokaryote?

  A prokaryote is a single-celled organism made up of prokaryotic cells
• What are the main subcellular structures found in most animal cells?

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• What is the function of the nucleus in an animal cell?

  It contains genetic material that controls the activities of the cell
• What role does the cytoplasm play in a cell?

  It is the gel-like substance where most chemical reactions happen
• What is the function of the cell membrane?

  It holds the cell together and controls what goes in and out
• Where do most reactions for aerobic respiration take place in a cell?

  In the mitochondria
• What is the function of ribosomes in a cell?

  They are where proteins are made
• What additional structures do plant cells have compared to animal cells?

  • Rigid cell wall
  • Permanent vacuole
  • Chloroplasts
• What is contained in the permanent vacuole of a plant cell?

  Cell sap, a weak solution of sugar and salts
• What is the role of the rigid cell wall in plant cells?

  It supports and strengthens the cell
• What is the function of chloroplasts in plant cells?

  They are where photosynthesis occurs
• What type of DNA do bacterial cells have?

  They have a single circular strand of DNA that floats freely in the cytoplasm
• What are plasmids in bacterial cells?

  Small rings of DNA
• What do bacterial cells lack compared to eukaryotic cells?

  Chloroplasts and mitochondria
• What are the two main types of microscopes and their functions?

  • Light microscopes: use light and lenses to magnify specimens
  • Electron microscopes: use electrons for higher magnification and resolution
• What is the resolution of a microscope?

  It is the ability to distinguish between two points
• How do you calculate magnification?

  Magnification = image size / real size
• If a specimen is 50 µm wide and magnified ×100, what is the image size?

  5 mm
• How would you write 0.0025 mm in standard form?

  1. 5 × 10⁻³
• Why is standard form useful in microscopy?

  It helps to write very big or small numbers in a manageable way
• What are the steps to prepare a slide for viewing under a light microscope?

  1. Add a drop of water to a slide
  2. Place specimen in water
  3. Add a drop of stain (iodine solution)
  4. Cover with a cover slip
• What are the steps to use a light microscope to view a slide?

  1. Clip the slide onto the stage
  2. Select the lowest-powered objective lens
  3. Use coarse adjustment to focus
  4. Adjust with fine adjustment for clarity
  5. Swap to a higher-powered lens if needed
• What is differentiation in cells?

  • The process by which a cell changes to become specialized
  • Involves developing different subcellular structures
• What should you include when drawing observations from a microscope?

  A title, magnification, and labels for important features
• What happens to most animal cells' ability to differentiate as they develop?

  They lose the ability to differentiate at an early stage
• What are stem cells?

  Undifferentiated cells that can divide to produce more undifferentiated cells
• What are examples of specialized cells and their functions?

  • Sperm cells: reproduction
  • Nerve cells: rapid signaling
  • Muscle cells: contraction
  • Root hair cells: absorbing water and minerals
  • Phloem and xylem cells: transporting substances
• What is the function of sperm cells?

  To deliver male DNA to the female DNA
• How are nerve cells specialized for their function?

  They are long and have branched connections for signaling
• What is the role of muscle cells?

  To contract quickly
• How do root hair cells aid in water absorption?

  They have long "hairs" that increase surface area
• What is the function of phloem and xylem cells?

  To transport substances like food and water in plants
• What do chromosomes contain?

  Genetic information
• What are chromosomes made of?

  Coiled-up lengths of DNA molecules
• How many copies of each chromosome do body cells normally have?

  Two copies, one from each parent
• What is the cell cycle?

  A series of stages that body cells go through to divide
• What is mitosis?

  The stage of the cell cycle when the cell divides