P1 - Cell Biology

• Name the two main types of cell.

  Prokaryotic, eukaryotic
• Name the two main types of eukaryotes


  Plants, animals
• Name 3 organelles ALL eukaryotes have.


  Cell membrane, cytoplasm, nucleus
• Name one type of prokaryote.

  Bacteria
• Name three organelles prokaryotic cells ALWAYS have


  Cell membrane, cytoplasm, cell wall
• How is DNA stored in prokaryotic cells?


  All DNA is found in a single loop, and there may be one or more smaller rings or DNA called plasmids.
• How large are plant cells? Give your answer in micrometers.


  10-100 micrometers
• How large are animal cells? Give your answer in micrometers


  10-30 micrometers
• How large are bacterial cells? Give your answer in micrometers


  0.2-2 micrometers
• What does centi- mean?


  x10^-2
• What does milli- mean?


  x10^-3
• What does micro- mean?


  x10^-6
• What does nano- mean?


  x10^-9
• What do nuclei do, and what does it contain?


  They contain DNA which controls the cell
• What do cell membranes do?


  They control what enters and leaves the cell
• What do mitochondria do and what do they contain?


  They contain enzymes that allow aerobic respiration to occur
• What do chloroplasts do and what do they contain?


  They contain enzymes and chlorophyll that allow photosynthesis to occur
• What do plasmids do and what do they contain?


  They contain DNA that enhances the survival of an organism.
• What do cells walls do and what do they contain?


  They contain cellulose that strengthens the cell.
• What do permanent vacuoles do and what do they contain?


  They contain cell sap that keeps the cell turgid
• What does cytoplasm do and what does it contain?


  It contains enzymes which allow chemical reactions to take place in the cell
• What do ribosomes do and what do they contain?


  They contain enzymes which allow protein synthesis to occur
• What 5 organelles do most animal cells contain?


  Nucleus, Cytoplasm, Cell Membrane, Mitochondria, Ribosomes
• What 3 organelles do plants often have that animal cells don't.


  Chloroplasts, Permanent Vacuole, Cell Wall
• On an image of a plant cell, what are the two outermost organelles called, in order of outermost to innermost?

  Cell Wall, then Cell Membrane
• On an image of a plant cell, what are two large circles/rectangles inside the cell called, in order of largest to smallest?

  Permanent Vacuole, then Nucleus
• On an image of a plant cell, what are the two types of very small but visible "dots" in the cell called, starting with the organelle only present in plants?


  Chloroplasts, then mitochondria
• On an image of a plant cell, what is the space inside of a cell called? What is the name of the organelle that usually cannot be seen on a diagram of a cell?


  Cytoplasm, then ribosomes
• For the Microscopy Practical, how do you focus on the slide?


  Use the lowest power objective lens. Slowly turn the course focusing wheel until the cells come into focus, then use the fine focusing wheel to make the focus perfect,
• For the Microscopy Practical, how do you include a magnification scale?

  Put a clear ruler in view of the microscope. On your drawing, put a line representing one millimetre. This is a scale bar. Include a magnification.
• For the Microscopy Practical, how would you prepare a microscope slide of onion epidermal cells?


  Using forceps, peel a thin layer of cells from an onion which has been cut in half with a knife. Place these cells on a slide, add a drop of iodine stain, and using clean forceps put a coverslip over the cells without trapping air bubbles. Place this slide on the microscope stage.
• How are sperm cells adapted to their function? Explain four ways.

  They have an acrosome which contains enzymes which break down an egg's wall. They also contain half the amount of chromosomes in the nucleus so that when it fertilises an egg the embryo has one full set of DNA. They contain many mitochondria to provide the cell with enough energy to swim towards the egg, and they a flagellum which makes the cell streamlined so it can swim to the egg faster.
• How are nerve cells adapted to their function? Explain three ways.

  They have a long thin axon, which allows electrical signals to travel very fast without hitting a synapse. They have an insulating myelin sheath which makes the signal travel faster, and they have many dendrites so they can receive signals from many cells.
• How are muscle cells adapted to their function? Explain three ways


  They are long so can slide over each other easily. They contain lots of mitochondria so the cell has enough energy to contract to cause movement. They contain glycogen which can be converted to glucose for respiration so the cell can contract to cause movement.
• How are root hair cells adapted to their function? Explain four ways.


  They have a large protrusion which increases surface area so diffusion and osmosis is faster. They have a large permanent vacuole that stores water so there is a larger water concentration gradient for osmosis. They have many mitochondria to provide energy for active transport. They have no chloroplasts to make room for other organelles and because there is no light for photosynthesis underground.
• How are xylem cells adapted to their functions? Explain three ways.


  They are hollow which allows them to transport water up and down the cell. They contain lignin which strengthens the cell so they can withstand water pressure, and they are dead so they do not use up unnecessary nutrients.
• How are phloem cells adapted to their function? Explain two ways.


  They have sieve plates which allows them to form tubes which sugar can be transported. They also have almost no organelles so that there is more room for dissolved substances to be transported. This means that the cell must have companion cells to provide it with nutrients.
• Explain the importance of cell differentiation.


  It allows unspecialised stem cells to become specialised cells, and it allows cells to perform specific functions. This makes it important for growth and development of embryos and seedlings, and for repair of blood and plant tissue.
• When do cells differentiate in animals?


  At an early stage.
• When do cells differentiate in plants?


  They retain the ability to differentiate throughout life.