Does anybody have any tips to distinguish between some of the main organelles in cells in case we have to identify pictures of them?
I remember some of the main ones by using how the names of the organelle to see what it looks like. For example, rough ER has spikes which kinda reminds me of sandpaper which is ROUGH too. Another one that is easy to use with this rule is the golgi apparatus because the structure looks like it is composed of l and o looking figures just like the word golgi.
The mitochondria always has the matrix (Looks like a maze) and it'll have it's own membrane (endosymboisis... predicted that it used to be its "own thing"). In some cells too, like muscle cells, there will be LOTS of them.
If the question tells you what type of cell it is, that should help you distingush between organelles too :)
What was the significance of the falsifications of the Davson-Danielli model?
The falsification of the Davson-Danielli model led to the proposal of the new Singer-Nicolson model. The Singer-Nicolson model shows how proteins are embedded within the fluid-mosaic bilayer rather than in their own seperate layers. This model is now used by scientists all over the world.
And they disproved the original model by injecting two different colored dyes into two different cells. When the cells fused and the two colors mixed, they realized that the proteins were mobile, not fixed.
Explain passive transport across membranes by simple diffusion and facilitated diffusion.
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