Biology, 1.1, 1.2, 1.3 1.4, 1.5, 1.6 of AS unit 1


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  • A polar molecule, which has no overall charge.
  • When 2 water molecules contact, opposites attract, forming a Hydrogen bond.
  • The sticking together of water molecules is called Cohesion.
  • High surface tension.
  • Water is a solvent.
  • Water has a specific heat, a large anount of water is needed to heat water.
  • High latent heat.
  • Maxium density is 4 degrees.
  • Ice is less dence than water.

Water potential

  • The higher WP implies a greater tendency of water to leave a system. Water will diffuse from a region of less negative (higher) WP to one of more negative (lower) WP.
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  • Contain carbon, hydrogen, oxygen.
  • Two main functions,
    • Act as a source of energy for plants + animals.
    • To play a structural role in plant cell walls, eg Cellulose.
  • Monosaccharides
  • Relitivly small molecules, (CH20), building blocks for bigger ones.
    • When n= 3 Triose- metabolism.
    • When n= 5 Pentose- Nucleic acid.
    • When n=6 Hexose- eg glucose, main source of energy.
  • Disaccharides
  • Two Monosaccharides linked together.
  • Formed by a Glycosidic bond, this eliminates water, this is called a Condensation reaction.

           Monosaccharides     Disaccaharides           Found

  • Glucose+Glucose=         Maltose:             Malt sugar
  • Glucose+Fructose=        Sucrose:            Cane sugar
  • Glucose+Galactose=       Latose:              Milk sugard
  • Polysaccharies
  • Large complex molecules. Many monosaccharides together.
  • 2 types: Starch (plants) and Glycogen ( animals)
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Cell structure


  • Controles the cells activity and retains chromosomes.
  • Bound by a double membrane, the nuclear memebrane (Nuclear envelope) has pores in it to allow transport or mRNA and nucleotides.
  • Contains coils of chromatin. The nucleolous makes RNA needed for Ribosomes.


  • Double membrane,
  •  (
  • Aerobic respiration occurs here.
  • Production of ATP.

Endoplasmic reticulum

  • Rough ER and Smooth ER.
  • Rough ER has Ribosomes on the out side of it. Transports protiens made by the ribosomes, found in large cells.
  • Smooth ER has membranes with less ribosomes. Concerned with the nucleolous.


  • 1 large + 1 small sub unit. Made in the nucleolous, from ribosomal RNA and protein. Improtant in protein synthisis.

Golgi body

  • Similar to the ER but more compact. Formed by rought ER.
  • It is like a packaging center, as it packages and then sends of proteins.


  • Small vacuoles are formed when portions of the golgi body are pinched off.
  • Contains digestive enzymes.
  • Destroy worn out cells.


  • Found in animal cells.
  • Located outside the nucleous.

The following things are all found in plants.


  • Found in photosynthesising tissue.
  • They have a double membrane.
  • Used to make energy from light energy.


  • A large fluid- filled membrane sac, with a single membrane (The tonoplast)
  • Contains cell sap.
  • Used as structural support for the cell.

Cellulose cell wall

  • Cell wall consits of cellulose microfibrils.
  • Main functions:
    • Provide strenghts+ support
    • Permit the movement of water from the cell to cell.


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Prokaryote & Eukaryote cells


·       No membrane bound organelles.

·        Found in plants, animals, fungi and protocists.

·       DNA lies free in the cytoplasm.

·         Membrane bound organelles.

·       No nuclear membrane in ER.


·       DNA located in chrosomes.

·       Ribosome’s are smaller.

·       Distinct membrane bound nucleus.

·       Cell wall containing marein.

·       Ribosome’s are larger.

        Cell wall in plants made of cellulose

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Mitosis and Meiosis.


  • Mitosis produces two daughter cells geneticaly identical to the parent cell.
  • Interphase- Longest part, produces organelles. DNA is doubled during this period.
  • Prophase:
    • Chromosomes condense, to long thin threads.
    • The centrioles devide, and move to opposite ends of the cell.
    • Protein microtubules form from each centriole and a spindle develops from pole to pole.
    • Nuclear membrane distegates and nucleolus disappears.
    • Pairs of chromatids can be clearly seen.
  • Metaphase-Chromosomes arange themselves at the center of the spindle.
  • Anaphase- Rapid stage.
    •   Centromere splits and spindle fibers contract and pull chromatids to the poles.
  • Telophase- The final stage.
    • Chromsomes at the poles, they then uncoil and lengthen,
    • spindle brakes down,
    • centrioles replicate, Nucleoli appears.
    • A new cell wall is laid down.


  • Two devisons resulting in 4 daughter cells. The number of chromosomes are halved.
  • Homologous chromosomes pair up.
  • Daughter cells are genetically different.

Meiosis and variation

  • Sources of variation are essential.
  • Three different ways to create variation.
    • Each of the chromosomes carry different genetic material.
    • Pairs of homologous chromosomes arrange themselves randomly on the spindle during metaphase. 
    • Crossing over during chiasmata formation during prophase.+ 
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Just what I needed. Some quick notes to look over before exam!!!!


Just what I needed. Some quick notes to look over before exam!!!!

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