Eukaryotic and prokaryotic cell structureEdexcel A-Level Biology A: Subtopic test

1. 1
   A technician examines a transmission electron micrograph of a liver cell. The cell has a large round nucleus containing a densely staining region, many rod-shaped structures with a folded inner membrane, a stack of flattened membrane-bound sacs with small vesicles budding from the edges, and many small round structures bounded by a single membrane and containing digestive enzymes.

   (a)

   Which organelle is the rod-shaped structure with a folded inner membrane?

   [1 mark]

   • ALysosome
   • BGolgi apparatus
   • CMitochondrion
   • DCentriole

   (b)

   Which process takes place in the densely staining region of the nucleus?

   [1 mark]

   • AMaking ribosomal RNA and assembling ribosomes
   • BAerobic respiration
   • CPackaging proteins into vesicles for secretion
   • DBreaking down worn-out organelles

   (c)

   The cell contains many mitochondria. Explain how the structure of a mitochondrion makes it well suited to producing ATP.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A microbiologist compares a rod-shaped bacterium with a yeast cell. The bacterium has a cell wall, a capsule, a flagellum, small ribosomes and a loop of DNA lying free in the cytoplasm. The yeast cell is eukaryotic.

   (a)

   Which structure is present in the yeast cell but not in the bacterium?

   [1 mark]

   • ARibosomes
   • BA cell wall
   • CA cell-surface membrane
   • DA nucleus enclosed by a nuclear envelope

   (b)

   Which statement describes a function of the bacterial capsule?

   [1 mark]

   • AIt makes proteins
   • BIt protects the cell, for example from drying out and from being engulfed by phagocytes
   • CIt moves the bacterium through liquid
   • DIt stores the bacterium's genetic information

   (c)

   An antibiotic binds to the ribosomes of the bacterium but does not stop protein synthesis in human cells. Suggest why.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A student studies an electron micrograph of a mitochondrion. On the printed micrograph the mitochondrion measures 45 mm in length and the magnification of the micrograph is ×15 000. The student's teacher says that a light microscope could not show the internal structure of the mitochondrion.

   (a)

   Calculate the actual length of the mitochondrion. Give your answer in micrometres (µm).

   [3 marks]

   (b)

   Explain why a light microscope could not show the internal structure of the mitochondrion.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   Cell X comes from a bacterium found in a hot spring. It has a cell wall, a capsule, a flagellum, ribosomes and a loop of DNA lying free in the cytoplasm, and it has no membrane-bound organelles. Cell Y is a human cell from the lining of the small intestine. It has a nucleus containing a nucleolus, many mitochondria, rough endoplasmic reticulum, a Golgi apparatus, lysosomes and centrioles.

   (a)

   Compare the structure of cell X with the structure of cell Y, and use your comparison to explain why cell X is a prokaryotic cell.

   [6 marks]

   (b)

   Explain the roles of the nucleus, the nucleolus, lysosomes and centrioles in cell Y.

   [6 marks]

   Total for question 4: 12 marks

End of questions