Biology Topic 1

  • Created by: Tia-H
  • Created on: 04-04-19 18:55

Cell Processes


  • High to Low concentraton.
  • Passive, random movement of particles.
  • Rate affected by concentration and temp.


  • Semi-permeable membrane.
  • Animal cell- burst.

Cell Division - For Growth And Repair

  • Mitosis 1) DNA replicates 2) Nucleus divides 3) Cell divides   =     Identicle cells.
  • Chromosomes- X shaped, Made of protein, contain all DNA code.

Active Transport

  • Requires energy- Cells have a lot of mitochondria,for mineral absorbtion.e.g gut absorbs sugar.       concentartion gradient increases.
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Magnification= Image Size / Object size






Parts Of The Microscope:

  • Lens - Eyepiece and objective.
  • Stage - Where you put the slide.
  • Electron - 3D image. Large Magnification. Expensive.
  • Resolving Power - Bigger the power, the easier to distinguish between particles.
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Stem Cells- Embryos and Adult Stem Cells

  • Uses - Insulin, paralysis, blindnes, growing / repairing organs.
  • Plants - Reduce extinction, largen, saves costs.
  • Ethics - Religion, interfere with reputation.
  • Cancer - The embryo cells divide and grow fast.
  • Adult cells can be infected with viruses - Theraputic cloning makes embryos form.
  • Undiferentiated cell - egg and sperm cell = zygote.

Differentiation - Cell that is specified for functions

  • Animal - Adult stem cells replace faulty blood cells.
  • plant - Differentiate through entire life (can always change).

Exchanging Materials

  • Large Surface Area: Volume Ratio.
  • Small intestine.
  • Stomata.
  • Alvioli - Thin and moist, O2 and CO2.
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Specialised Cells

Algae - Cell wall, chloroplasts, like a plant.

Prokaryotes - (Bacteria)- Single celled organism, no nucleus, plasmid ring, flagella, slime capsule.

Eukaryotes - (Animal & plant cells)- Nucleus contains the genetic material (DNA).

Muscle - Store glycogen, proteins, mitochondria.

Sperm - Flagella, acrosome (contains digestive enzymes), mitochondria, streamlined.

Nerves - Lots of connections, axon (carries impulses), transmitter for chemicals.

Root Hair - Large vacuole and surface area, mitochondria.

Xylem - Transports water, chemicals: lignin (make rigid, forms hollow tubes).

Phloem - Food made in photosynthesis, cell wall breaks down.

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Osmosis Potato Practical

Required Practical

Investigating the effect of different concentration of sugar solution on plant tissue


  • Cut cylinders of potato tissue and measure each mass.
  • Place the potato in different concentrations of the sugar solution.
  • After 30 minutes, mesure their mass again.
  • If the potato changes in mass it has gained or lost water in osmosis. Osmosis is high to low.


  • Independent - (Changed) - Concentration of sugar solution.
  • Dependent - (Measured) - Change in mass of potato.
  • Control - (Stays same) - Temperature, length of time, volume of solution.
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Osmosis Potato Practical

Mistakes or errors:

  • Potato needs to be left a long time for a significant change in mass.
  • Before weighing the potato a second time, it must be blotted on a paper towel to remove excess solution.

Hazards and risks:

  • Care must be taken when cutting the cylinders of potato to ruduce risk of cutting yourself.

Osmosis is the diffusion of particles in water from low concentration to a high concentration through a partially permeable membrane.

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