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Biology help (OCR A)

Could you answer these questions please?

Do you need to know about cell theory? - mentioned on first page

Last question: I don't get what the spec means by: "The use of microscopy to investigate different types of cells and cell structure in a range of eukaryotic cells"

My textbook says: "by making visible the individual cells which make up a multicellular oganism, microscopes allow us to investigate details of how their cell structure relate to their function"

Can you explain it with the textbook or combine the two together to get an easier explanation

Thank you! Sorry for all the questions, I just really confused
Hello!

Yes, you do need to know about cell theory, including the endosymbiotic theory.

The thing on the spec means that to pass the course you need to be able to use a microscope to look at plant/animal cells and do all the necessary microscope calculations (calibration and i=am).

The textbook is saying that since the invention of the microscope, we've been able to see that we (and many other organisms) are made up of many cells. It has allowed us to find out how those cells work, how their structure relates to their function etc. It basically means we finally know what we're made of - hooray!

Hope this is helpful. Sorry if it isn't, your question was really unclear but I did my best.
Original post by JustJusty
Hello!

Yes, you do need to know about cell theory, including the endosymbiotic theory.

The thing on the spec means that to pass the course you need to be able to use a microscope to look at plant/animal cells and do all the necessary microscope calculations (calibration and i=am).

The textbook is saying that since the invention of the microscope, we've been able to see that we (and many other organisms) are made up of many cells. It has allowed us to find out how those cells work, how their structure relates to their function etc. It basically means we finally know what we're made of - hooray!

Hope this is helpful. Sorry if it isn't, your question was really unclear but I did my best.


Thank you so much!!!
Do you need to make notes that are worded exactly like the spec? (Thats what i was trying to say by the last question)

Does it ask about cell theory on the spec? Sorry if it seems like im questioning you. Oh and what is endosymbiotic theory?

Do you need to know the components of microscope e.g. stage, eyepiece?
And the same for the other microscopes?

Last question;
For the preparation of a light microscope my textbook talks about mounting a slide (and gives a few example like wet mount) but a few pages after that it talks about preparing a slide (e.g. cutting/ using alcohol etc.. ) are they linked together?
Original post by shohaib712
Thank you so much!!!
Do you need to make notes that are worded exactly like the spec? (Thats what i was trying to say by the last question)

Does it ask about cell theory on the spec? Sorry if it seems like im questioning you. Oh and what is endosymbiotic theory?

Do you need to know the components of microscope e.g. stage, eyepiece?
And the same for the other microscopes?

Last question;
For the preparation of a light microscope my textbook talks about mounting a slide (and gives a few example like wet mount) but a few pages after that it talks about preparing a slide (e.g. cutting/ using alcohol etc.. ) are they linked together?


So sorry for replying late! I haven't been on TSR for a few days.

Any definitions or theories, word them exactly like they are worded in the textbook/on the spec. There are always key terms which get you marks, and you don't want to miss any out. They're fairly easy to memorise.

It does ask about cell theory, but for that you only need to remember one or two sentences.

Endosymbiotic theory (in my own words): it's possible that a long time ago organelles such as chloroplasts and mitochondria were independent prokaryotic (bacteria-like, with no nucleus) organisms. One day they were engulfed by a larger cell, which is how eukaryotic cells (like our own) came into being. When the cell replicated, it produced its own chloroplasts and mitochondria. The big cell relies on those organelles for their functions, and the organelles rely on the cell. There is evidence for this theory which you have to memorise. Your textbook will list it, but I can 100% guarantee that they've asked about it before.

You will need to learn the components of a light microscope. You also need to know the advantages, disadvantages, resolutions, magnifications and images produced by light, transmission electron, scanning electron and laser confocal microscopes.

I'm not really sure what you mean by your last question, but I will do my best.
You need to know:
-how to mount a slide (e.g. a cover slip is placed down from a 45 degree angle)
-the different types of stains and what they stain
-microscope calculations and calibration
-that you start with the lowest power lens and work your way up
-that you start with the stage all the way down and then move it up to focus
-transverse and longitudinal section

Hope I helped, in case you haven't got the answers yet. Good luck!
Thank you so much and no problem :biggrin:

I've started using 2 textbooks (cgp and official textbook) and with the cgp book it goes into more detail on how to prepare a wet mount which is not given in the official textbook :/ could you explain how to prepare a wet mount please? Just so I know that I made the notes correctly.

I don't think I need to know about confocal lenses magnification and res as it's not given in the spec nor the textbook it only says that you need to know the other three in detail. + I don't think I need to know the images produced by confocal, is that true?

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