Biology topic 1

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


  Prokaryotic and eukaryotic
• What are the main components of eukaryotic cells?

  • Cell membrane
  • Cytoplasm
  • Nucleus containing DNA
• What are the components of prokaryotic bacterial cells?


  Cell wall, cell membrane, cytoplasm, single circular strand of DNA, and plasmids
• What is the function of organelles in a cell?


  They perform different functions necessary for the cell's survival and operation
• What are the prefixes for common metric units and their values?


  • Centi: 0.01
  • Milli: 0.001
  • Micro: 0.000001
  • Nano: 0.000000001
• What are the functions of subcellular structures in animal and plant cells?

  • Nucleus: Contains DNA for protein coding
  • Cytoplasm: Site of chemical reactions
  • Cell membrane: Controls entry and exit of substances
  • Mitochondria: Site of aerobic respiration
  • Ribosomes: Site of protein synthesis
  • Chloroplasts (in plants): Site of photosynthesis
  • Permanent vacuole (in plants): Contains cell sap for rigidity
  • Cell wall (in plants): Provides strength
• What is the role of the nucleus in a cell?


  It contains DNA coding for proteins needed to build new cells
• What is the function of mitochondria in a cell?


  They are where aerobic respiration occurs, providing energy
• What is the function of ribosomes?


  They are the site of protein synthesis
• What is the role of chloroplasts in plant cells?


  They are where photosynthesis takes place
• What is the function of the permanent vacuole in plant cells?


  It contains cell sap and improves cell rigidity
• What is the composition of the cell wall in plant cells?


  It is made from cellulose
• How do bacterial cells differ from eukaryotic cells in terms of organelles?


  Bacterial cells have fewer organelles and lack a nucleus
• How can you calculate the size or area of sub-cellular structures?


  By finding a shape that resembles it and applying the appropriate area formula
• What is cell differentiation?


  • Process where cells gain new sub-cellular structures
  • Suits them for specific roles
  • Can occur early in development or throughout life (as in stem cells)
• What are examples of specialized cells in animals?

  1. Sperm cells: Carry male DNA
  2. Nerve cells: Transmit electrical signals
  3. Muscle cells: Contract to move bones
• What adaptations do sperm cells have for their function?


  Streamlined head, long tail, many mitochondria, and acrosome with enzymes
• How are nerve cells specialized for their function?


  They have a long axon and many dendrites for quick signal transmission
• What is the function of muscle cells?


  To contract quickly for movement
• What are examples of specialized cells in plants?


  1. Root hair cells: Absorb water and minerals
  2. Xylem cells: Transport water and minerals
  3. Phloem cells: Carry products of photosynthesis
• What adaptations do root hair cells have for their function?


  Large surface area and a large permanent vacuole
• How do xylem cells transport water?


  They become hollow and form continuous tubes
• What is the role of phloem cells?


  To transport the products of photosynthesis throughout the plant
• What is the process of differentiation in stem cells?


  • Stem cells undergo differentiation to form specialized cells
  • Involves switching genes on or off
  • Produces different proteins for specific functions
• How do animal cells differ from plant cells in terms of differentiation?


  Most animal cells differentiate early and lose the ability, while many plant cells can differentiate throughout life
• What is the maximum magnification of a light microscope?


  x2000
• Who first observed cells and when?

  Robert Hooke in 1665
• What is the function of the objective lens in a light microscope?


  It produces a magnified image of the specimen
• What is the resolving power of a light microscope?


  200 nm
• What is the difference between scanning and transmission electron microscopes?


  Scanning electron microscopes create 3D images, while transmission electron microscopes create 2D images
• What is the maximum magnification of an electron microscope?


  x2,000,000
• What is the formula for calculating the size of an object using a microscope?


  Size of object = size of image / magnification
• What is standard form used for in microscopy?


  To handle very large or small numbers
• What is the culture medium for growing microorganisms?


  A mixture containing carbohydrates, minerals, proteins, and vitamins
• What are the two methods for culturing microorganisms?

  1. Nutrient broth solution
  2. Agar gel plate
• Why must Petri dishes and culture media be sterilized before use?


  To prevent contamination by unwanted microorganisms
• How do bacteria multiply in a suitable environment?


  By binary fission, splitting into two every 20 minutes
• What is the formula for calculating the number of bacteria at the end of a growth period?


  Bacteria at beginning x 2^{number of divisions} = bacteria at end
• What is the purpose of testing antibiotics on bacteria?


  To determine their effectiveness in killing bacteria
• What is the role of the inhibition zone in antibiotic testing?


  It indicates the effectiveness of the antibiotic by showing the area where bacteria have died