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Cell structure

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Question 14

To study the internal ultrastructure of cell organelles, such as ribosomes (diameter ≈22 nm\approx 22\text{ nm}≈22 nm) and the inner membranes of mitochondria, a high-resolution microscope must be selected.

Which row in the table below correctly identifies the microscope type required, the physical basis for its high resolution, and the resulting specimen conditions and image type?

Microscope TypePhysical Basis for ResolutionImage Nature & Specimen State
Row ATransmission Electron MicroscopeWavelength of electron beam is much shorter than light2D internal ultrastructure; dead specimen
Row BScanning Electron MicroscopeWavelength of electron beam is much longer than light3D surface structure; living specimen
Row CTransmission Electron MicroscopeElectromagnetic lenses focus visible light to a smaller point3D internal structure; living specimen
Row DLight MicroscopeLight waves have a shorter wavelength than electron beams2D colour image; dead or living specimen
A

Row A

B

Row B

C

Row C

D

Row D

Markscheme

Cell structure Questions

  1. A Level
  2. /Biology
  3. /Cell structure

22 exam-style questions on OCR A A Level Biology Cell structure. Each one has a worked solution and a mark scheme showing where the marks go.

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