bio t1 -cell biology topic 1

• What are the two main types of cells in living organisms?

  Prokaryotic and eukaryotic
• Which types of cells are classified as eukaryotic?

  Animal and plant cells
• What are the main components of animal and plant cells?

  Cell membrane, cytoplasm, and nucleus containing DNA
• What structures are found in bacterial cells?

  Cell wall, cell membrane, cytoplasm, single circular strand of DNA, and plasmids
• What are organelles?


  Structures in a cell that have different functions
• How do we use orders of magnitude to compare sizes?

  By expressing how many times larger or smaller one object is compared to another
• What does a prefix like 'centi' indicate in measurements?

  It multiplies the unit by 0.01
• What are the functions of the nucleus, cytoplasm, and cell membrane in animal and plant cells?


  • Nucleus: Contains DNA coding for proteins needed to build new cells, enclosed in a nuclear membrane.
  • Cytoplasm: Liquid substance where chemical reactions occur, containing enzymes and organelles.
  • Cell membrane: Controls what enters and leaves the cell.
• What are the functions of mitochondria and ribosomes in cells?

  • Mitochondria: Where aerobic respiration occurs, providing energy for the cell.
  • Ribosomes: Where protein synthesis occurs, found on the rough endoplasmic reticulum.
• What are the unique structures and functions of plant cells compared to animal cells?

  • Chloroplasts: Where photosynthesis takes place, containing chlorophyll.
  • Permanent vacuole: Contains cell sap, improves cell rigidity.
  • Cell wall: Made from cellulose, provides strength to the cell.
• How do bacterial cells differ from eukaryotic cells in terms of structure?

  Bacterial cells have a cell wall made of peptidoglycan and a single circular strand of DNA, while eukaryotic cells have a nucleus.
• What is the process of cell differentiation?

  It is the process by which a cell gains new sub-cellular structures to become suited to its role.
• What are examples of specialised cells in animals and their functions?

  1. Sperm cells: Carry male DNA to the egg cell.
  2. Nerve cells: Transmit electrical signals quickly.
  3. Muscle cells: Contract to move bones or squeeze.
• What are examples of specialised cells in plants and their functions?

  1. Root hair cells: Take up water and minerals from the soil.
  2. Xylem cells: Transport water and minerals up the plant.
  3. Phloem cells: Carry products of photosynthesis to all parts of the plant.
• What is the role of stem cells in differentiation?

  Stem cells undergo differentiation to form specialised cells by switching genes on or off.
• How do cell division processes differ in animals and plants?

  In animals, most cells differentiate early and lose the ability, while in plants, many cells can differentiate throughout life.
• Who first observed cells and in what year?

  Robert Hooke in 1665
• What are the main features of a light microscope?

  • Two lenses: objective and eyepiece.
  • Maximum magnification of x2000.
  • Resolving power of 200nm.
  • Used to view tissues, cells, and large sub-cellular structures.
• What are the main features of an electron microscope?

  • Uses electrons to form images.
  • Two types: scanning (3D images) and transmission (2D images).
  • Magnification up to x2,000,000.
  • Resolving power of 10nm (SEM) and 0.2nm (TEM).
• What is the formula for calculating magnification in a light microscope?

  Magnification = magnification of the eyepiece lens x magnification of the objective lens
• How do you calculate the size of an object using a microscope?

  Size of object = size of image / magnification
• What is standard form and how is it used in calculations?

  • A way to express very large or small numbers.
  • Involves multiplying a number by a power of 10.
  • The number multiplied must be between 1 and 10.
• What is the culture medium used for growing microorganisms composed of?

  Carbohydrates, minerals, proteins, and vitamins
• What is the first step in culturing microorganisms in nutrient broth solution?

  Making a suspension of bacteria to be grown and mixing it with sterile nutrient broth
• Why is cotton wool used when culturing microorganisms?

  To prevent air from contaminating the culture
• What is the purpose of shaking the flask when culturing microorganisms?

  To provide oxygen and evenly distribute the nutrients
• What is standard form used for in microscopy?


  It is useful for working with very large or small numbers.
• How does standard form work?

  By multiplying a certain number by a power of 10 to make it bigger or smaller.
• What is the requirement for the 'number' in standard form?

  It must be between 1 and 10.
• Convert $1.5 \times 10^{-5}$ to decimal form.


  0.000015
• Convert $3.4 \times 10^{3}$ to decimal form.


  3400
• What is the purpose of culturing microorganisms in the lab?

  • To study very small microorganisms
  • To grow many microorganisms using nutrients
• What does the culture medium for microorganisms contain?

  Carbohydrates, minerals, proteins, and vitamins.
• What are the two ways to grow microorganisms in the lab?

  1. In nutrient broth solution
  2. On an agar gel plate
• What is the process of growing microorganisms in nutrient broth solution?

  A suspension of bacteria is mixed with sterile nutrient broth and shaken to provide oxygen.
• What is the purpose of stoppering the flask with cotton wool during culturing?

  To prevent air from contaminating the culture.
• How are microorganisms grown on an agar gel plate?

  Bacteria form colonies on the surface of the agar after being spread evenly.
• What is the first step in making an agar gel plate?


  Pour hot sterilised agar jelly into a sterilised Petri dish.
• Why is it important to seal the lid of the Petri dish with tape?

  To stop airborne microorganisms from contaminating the culture.
• Why should the Petri dish be stored upside down during incubation?

  To prevent condensation from disrupting growth on the agar surface.