Cell structure and transport (biology)

• What are the three transport processes used by cells to take in substances and remove waste?

  Diffusion, osmosis, and active transport
• Why do cells need to control how much water they contain?

  To maintain homeostasis and proper cellular function
• What is diffusion?


  Diffusion is the net movement of particles from an area of high concentration to an area of low concentration down a concentration gradient.
• What factors affect the rate of diffusion?

  Temperature, surface area, and concentration gradient
• How does temperature affect the rate of diffusion?

  An increase in temperature causes particles to move more quickly, increasing the rate of diffusion.
• How does surface area influence diffusion?

  A larger surface area allows for more diffusion to take place, increasing the rate of diffusion.
• What is osmosis?


  Osmosis is the diffusion of water molecules from a dilute solution to a concentrated solution across a partially permeable membrane.
• What are the adaptations of exchange surfaces in large multicellular organisms?

  They have a large surface area, a thin membrane, and an efficient blood supply.
• What is active transport?

  Active transport is the movement of substances from an area of low concentration to an area of high concentration against a concentration gradient, requiring energy from respiration.
• Why do plants require active transport?

  To absorb mineral ions from very dilute solutions in the soil for healthy growth.
• How does active transport help in glucose absorption?

  It allows glucose molecules to be absorbed from lower concentrations in the gut into the blood, which has a higher glucose concentration.
• What is the definition of a eukaryotic cell?

  A eukaryotic cell has a nucleus and includes animal and plant cells.
• What are the main components of an animal cell?

  Nucleus, cell membrane, cytoplasm, mitochondria, ribosomes
• What is the function of mitochondria?

  They are the site of respiration and release energy for the cell to use.
• What is the role of ribosomes in a cell?

  Ribosomes are responsible for protein synthesis.
• What is the function of the cell wall in plant cells?

  The cell wall strengthens the cell and is made of cellulose.
• What is the function of chloroplasts?

  Chloroplasts are where photosynthesis takes place, trapping sunlight's energy using chlorophyll.
• What is the purpose of the permanent vacuole in plant cells?

  It helps to keep the cell turgid (swollen and rigid) to support the plant.
• What is a prokaryotic cell?

  A prokaryotic cell is smaller and does not have a nucleus; its DNA is free and forms a single loop.
• What is the function of plasmids in bacterial cells?

  Plasmids are small rings of extra bacterial DNA.
• How do light microscopes work?

  Light microscopes shine light through a specimen, refracting it through lenses to form a magnified image.
• How do you calculate total magnification of a microscope?

  Total magnification is calculated by multiplying the objective lens magnification by the eyepiece lens magnification.
• If the objective lens magnification is 10x and the eyepiece lens magnification is 20x, what is the total magnification?

  Total magnification = $10 \times 20 =$$200$
• What is the difference between resolution and magnification?


  Resolution is the ability to distinguish between two separate points, while magnification is how many times bigger the image is than the actual object.
• What is the best resolution achievable by light microscopes?

  The best light microscopes can achieve a resolution of 0.2 µm.
• What is the maximum magnification of an electron microscope?

  An electron microscope can achieve magnifications of up to x2000000.
• Why do electron microscopes provide greater resolution than light microscopes?

  Electron microscopes use a beam of electrons instead of light, allowing for greater magnification and resolution.
• How do orders of magnitude relate to size comparisons?

  If something is 10 times bigger than something else, it is 1 order of magnitude bigger; if it is 100 times bigger, it is 2 orders of magnitude bigger.
• What is the size of a typical eukaryotic cell?

  Typical eukaryotic cells are around 10-100 µm in size.
• What is the size of a typical prokaryotic cell?

  Typical prokaryotic cells are around 0.1-5.0 µm in size.
• What is the size of a virus?

  Viruses are typically around 20-300 nm in size.
• What is the function of the slime capsule in bacterial cells?

  The slime capsule protects the bacterial cell and prevents it from drying out.
• What is the function of flagella in bacterial cells?

  Flagella are tail-like protein strands that allow the bacterial cell to move around.
• What are the adaptations of exchange surfaces in large multicellular organisms?

  • Large surface area
  • Thin membrane for short diffusion path
  • Efficient blood supply
  • Well ventilated (in animal lungs)
• What are the main components of a eukaryotic cell?

  • Nucleus
  • Cell membrane
  • Cytoplasm
  • Mitochondria
  • Ribosomes
  • (Plant cells also have cell wall, chloroplasts, and vacuole)
• What are the main components of a prokaryotic cell?

  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Genetic material (DNA)
  • Plasmids
  • Flagella (not all bacteria have this)
• What are the differences between light and electron microscopes?

  • Light microscopes use light to magnify images, while electron microscopes use electrons.
  • Light microscopes have lower magnification (up to x2000) compared to electron microscopes (up to x2000000).
  • Electron microscopes provide greater resolution than light microscopes.
• What are the orders of magnitude in size comparisons?

  • 1 order of magnitude = 10 times bigger
  • 2 orders of magnitude = 100 times bigger
  • Each order of magnitude represents a tenfold increase in size.