1. 1
   A student compares a photomicrograph of an onion epidermal cell with one of a cheek cell. The onion cell shows a rigid box-like outline and green-free plastids, while the cheek cell has an irregular outline.

   (a)

   Which structure is present in the onion cell but absent from the cheek cell, giving it its rigid, regular shape?

   [1 mark]

   • ACell wall
   • BNucleus
   • CCell membrane
   • DCytoplasm

   (b)

   Which structure would the student expect to see in the onion cell that stores cell sap and helps maintain the cell's shape by pressing outwards on the cell wall?

   [1 mark]

   • AMitochondrion
   • BRibosome
   • CLarge permanent vacuole
   • DChloroplast

   (c)

   Describe two structures found in both the onion cell and the cheek cell, and state the function of each.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A microbiologist examines a bacterial cell and notes that, unlike the onion and cheek cells studied earlier, its genetic material is not enclosed within a nucleus.

   (a)

   Which structure describes how genetic material is arranged in a bacterial cell?

   [1 mark]

   • ALinear DNA within a membrane-bound nucleus
   • BCircular DNA free in the cytoplasm
   • CDNA stored only in mitochondria
   • DDNA contained within chloroplasts

   (b)

   The microbiologist also identifies small circular pieces of DNA in the bacterial cell, separate from the main circular chromosome. What are these structures called?

   [1 mark]

   • ARibosomes
   • BPlasmids
   • CVacuoles
   • DChloroplasts

   (c)

   State two structures that a bacterial cell has in common with the onion cell described earlier.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A researcher studies four specialised human and plant cells: a root hair cell, a palisade mesophyll cell, a neurone and a red blood cell.

   (a)

   State three ways in which cells can become specialised for a particular function, giving a named example for each from the list.

   [3 marks]

   (b)

   Explain how the structure of the red blood cell and the neurone are each adapted to carry out their specific functions.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A textbook diagram compares a generalised plant cell with a generalised animal cell, both viewed under a light microscope.

   (a)

   Explain the similarities and differences between the structure of a plant cell and an animal cell, referring to at least four named structures.

   [6 marks]

   (b)

   The textbook also compares the plant and animal cells with a generalised bacterial cell. Explain how the structure of a bacterial cell differs from that of the plant and animal cells, referring to at least four named structures.

   [6 marks]

   Total for question 4: 12 marks

End of questions