1. 1
   A school science technician prepares a slide of onion epidermis cells stained with iodine and views it under a light microscope. In the photograph taken through the microscope, the image of one onion cell measures 2 mm across, while the actual width of the cell is known to be 0.05 mm.

   (a)

   Which structure found in the onion cell is NOT present in a human cheek cell (an animal cell)?

   [1 mark]

   • ACytoplasm
   • BNucleus
   • CMitochondria
   • DCell wall

   (b)

   Using the formula magnification = image size ÷ actual size, calculate the magnification of the onion cell in the photograph, where the image size is 2 mm and the actual size is 0.05 mm.

   [1 mark]

   • A×4
   • B×40
   • C×400
   • D×4000

   (c)

   State two functions of structures found in the onion cell that are not present in an animal cell.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A hospital microbiology laboratory is investigating a bacterial infection. A sample is examined and found to contain rod-shaped cells with no visible nucleus, but with cytoplasm, ribosomes and a single loop of DNA. For comparison, a sample of white blood cells is taken from the same patient; these cells have a nucleus and other membrane-bound organelles such as mitochondria.

   (a)

   Which term describes cells, such as the bacterial cells found in the sample, that lack a nucleus and other membrane-bound organelles?

   [1 mark]

   • AEukaryotic
   • BSpecialised
   • CMulticellular
   • DProkaryotic

   (b)

   Which structure is found in the bacterial cell described but not in the patient's white blood cell?

   [1 mark]

   • ARibosomes
   • BCytoplasm
   • CCell membrane
   • DPlasmid

   (c)

   Describe two differences, other than the presence of a nucleus, between the bacterial cell and the patient's white blood cell.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A farmer notices that plant cells taken from a wilted leaf appear shrunken away from the cell wall when viewed under a microscope, while cells from a healthy, well-watered leaf on the same plant appear plump and pressed firmly against the cell wall.

   (a)

   Describe the structure and function of the chloroplast, and explain why chloroplasts are found in the leaf cells but not in the root cells of the same plant.

   [3 marks]

   (b)

   Explain, in terms of cell structures, why plant cells such as those in the leaf have a cell wall, vacuole and chloroplasts, while animal cells do not have these structures.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   In 1665, Robert Hooke first observed the cell-like structures of cork under a microscope, naming them 'cells'. Since then, microscopy has advanced enormously, and scientists can now distinguish in fine detail between the structures of animal cells, plant cells and bacterial cells.

   (a)

   Describe the structure and functions of the named structures found in a typical animal cell: cell membrane, cytoplasm, nucleus, mitochondria and ribosomes.

   [6 marks]

   (b)

   Describe the differences between prokaryotic cells (such as bacteria) and eukaryotic cells (such as animal and plant cells), and describe the structure of a bacterial cell.

   [6 marks]

   Total for question 4: 12 marks

End of questions