check out links below for a comprehensive note on cells 15/01/2017

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videos on cells
intro video on cells =
  1. pro & eukaryotic cells
  2. animal cells
  3. plant cells
  4. cell specialisation
videos on movement across cells
  1. diffusion

  2. osmosis
  4. active transport
  5. 2018 cell test
The chart below focuses on unicellular organisms pro and eukaryotes


The chart below focuses on ORGANISMS AND THE CELLS THAT DEFINE THEM unicellular and multicellular

external image types-of-cell.PNG
external image types-of-cell.PNG

external image prokaryote.jpg

external image images?q=tbn:ANd9GcS2ZKEvujrtLCgyWQoL8RwLpWzze3m8QJUsJyWv7EHsl4z5QKGu

notes and answers to work given for spr 1 2017

Egg project to show osmosis

videos on cells... details about microscopes used to create some of the pictures found in text books.

more on cells from bio crash course

more on cells khan academy

more on plant cells

Osmosis is the movement of water molecules from an area of high concentration (weak solution) to and area of low water concentration (strong solution) through a partially permable membrane.

Water moves both ways to balance up the concentrations. If there is more movement one way, we say there is a net movement of water into the area where there is less water.
external image osmosis_1.png

diffusion simple and effectively presented

simple video on osmosis

Osmosis makes plant cells swell. Water moves into the plant cell vacuole and pushes against the cell wall. The cell wall stops the cell from bursting We say this is tugid.
If a plant lacks water, it wilts and the cells become flaccid as water has moved out of the cell.
If a lot of water leaves the plant cell, the cytoplasm starts to peel away from the cell wall. We say the cell has undergone plasmolysis.



Osmosis in Animal Cells
Animal cells have no cell wall to stop them swelling. So if they are placed in pure water, they take in water by osmosis until they burstexternal image lysed_1.png

osmosis and diffusion are passive processes where molecules move down a concentration gradient until evenly distributed.These processes are slow thus as organisms increase in size and complexity the need to specialize cells and develop more efficient means of transporting substances become vital.

passive and active transport in cells
you do not have to learn for this level the terms isotonic/hypotonic or the cell membrane mechanism. focus on the differences between diffusion, osmosis and active transport

diffusiona and osmosis

below are some pictures of an experiment showing how
  • increase in volume/size = decrease in the surface area to volume ratio of the object
  • diffusion across the smallest cube is complete while the larger cubes show reducing degrees of penetration
  • all of this depend on the difference in surface area to volume ratios




cell specialization the process

Ensure that you take the following points
  • cell specialzation involves changing an undifferenciated cell into a specific type
  • it is irreversible once a cell has been determined in humans
except in some other organismsexample fish that are first female and later change into males
  • the cells become specific and efficient at a particular task
  • cell specialization or change can be influenced by chemicals internally (genes) or externally (proteins - hormones)
  • if man can manipulate this process in the future we will be able to generate and replace organs or parts of the human body