cell biology

• What are the subcellular structures in animal cells?

  • Nucleus: contains genetic material
  • Mitochondria: site of aerobic respiration
  • Cytoplasm: gel-like substance for reactions
  • Cell membrane: controls substance movement
  • Ribosomes: site of protein synthesis
• What additional structures are found in plant cells?

  • Rigid cell wall: supports and strengthens
  • Chloroplasts: site of photosynthesis
  • Permanent vacuole: contains cell sap
• What is cell differentiation?

  • Process where cells become specialized
  • Develop different subcellular structures
  • Allows cells to perform specific functions
  • Most differentiation occurs during development
• What are the characteristics of stem cells?

  • Can divide to produce more undifferentiated cells
  • Found in early human embryos
  • Adult stem cells found in specific locations
  • Limited differentiation in adult stem cells
  • Used in medical research
  • Plant stem cells found in meristems
• What is the cell cycle used for?

  • Growth
  • Development
  • Repair
• What happens during mitosis?

  1. Cell divides to produce new cells
  2. Increases subcellular structures and duplicates DNA
  3. Chromosomes line up and are pulled apart
  4. Membranes form around new chromosomes
  5. Cytoplasm and membrane divide
  6. Produces two identical daughter cells
• What adaptations do exchange surfaces have for efficient diffusion?

  • Thin membrane for short diffusion distance
  • Large surface area for more diffusion
  • Lots of blood vessels for quick exchange
  • Well-ventilated for gas exchange
• How does gas exchange occur in plants?

  • Carbon dioxide diffuses into leaf air spaces
  • Diffuses into cells for photosynthesis
  • Stomata on leaf underside allow gas exchange
  • Oxygen and water vapor diffuse out
  • Guard cells control stomata size
  • Flat shape increases surface area
• are viruses living organisms?

  no
• a unicellular organism is made of just one cell
• Plant and algal cells have a cell wall made of cellulose, which strengthens the cell
• In mature animals, cell division is mainly restricted to repair and replacement
• What happens to plant cells when placed in water?

  Water moves into the cell, causing expansion
• What occurs when a plant cell is placed in a concentrated solution?

  Water moves out, causing the cell to shrink
• What vegetable is commonly used to investigate osmosis?

  Potato
• Why do we peel the potato before the experiment?

  The skin can affect osmosis
• What tool is used to produce uniform potato cylinders?

  Cork borer
• What is the ideal length for potato cylinders?

  About three centimeters
• Why is it important to measure the length and mass of each cylinder?

  To assess the effect of osmosis accurately
• How much of a 0.5 molar sugar solution is added to the first test tube?

  10 centimeters cubed
• Why do we use distilled water instead of tap water?

  Distilled water has no dissolved substances
• What should you do after leaving the potato cylinders overnight?

  Gently roll them on paper towel
• Why is it important not to press on the cylinders when drying them?

  To avoid forcing water out of the cells
• What do you need to calculate after measuring the length and mass again?

  Percentage change in length and mass
• What is the formula for calculating percentage change?

  Percentage change = (change in value / original value) × 100
• What does it mean when the graph crosses the x-axis?

  No change in mass occurs
• What does the concentration at the x-axis crossing indicate?

  Approximate concentration inside the cell
• What is emphasized about the chemicals used in the tests?

  They are potentially hazardous
• What is the procedure for preparing a food sample for testing?

  • Grind food sample with distilled water
  • Make a paste
  • Transfer to a beaker and add more distilled water
  • Stir to dissolve chemicals
  • Filter to remove suspended particles
• What are the two main types of carbohydrates mentioned?

  Starch and sugars
• How do you test for starch in a food sample?

  Add iodine solution to the food solution
• What color does iodine turn if starch is present?

  Blue-black
• What color does iodine remain if no starch is present?

  Orange
• How do you test for sugars like glucose?

  Add Benedict solution and heat in water
• What color indicates a small amount of sugar in the Benedict test?

  Green
• What color indicates a lot of sugar in the Benedict test?

  Brick red
• What type of sugars does the Benedict test work for?

  Reducing sugars
• What is the test for proteins?

  Add Biuret solution to the food solution
• What color change indicates the presence of protein?

  Blue to purple or lilac
• What is the procedure for testing lipids?

  • Grind food with distilled water
  • Do not filter the solution
  • Transfer to a test tube
  • Add distilled water and ethanol
  • Gently shake the solution
  • Look for a white cloudy emulsion