Organelles & Compartmentalisation (DP IB Biology: HL): Exam Questions

The mitochondria are organelles within a eukaryotic cell that show compartmentalisation.

Define compartmentalisation.

In addition to the mitochondria, identify two other compartmentalised structures with double membranes characteristic of a eukaryotic cell.

Describe and explain the importance of the double membrane in mitochondria.

Prokaryotic cells lack compartmentalisation, which contrasts with eukaryotic cells. The graph below compares the rates of various stages in protein synthesis between prokaryotic and eukaryotic cells.

(i) Describe and explain the differences in transcription and translation seen between prokaryotic and eukaryotic cells.

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(ii) Suggest why RNA polymerase binding occurs more quickly in prokaryotes than Eukaryotes.

[1]

(iii) Post-translational modifications occur more slowly in eukaryotic cells as proteins are processed by other organelles.

Identify one other organelle involved in post-translational modifications and describe the role it plays in processing proteins.

[2]

State the function of the mitochondria.

Compare and contrast the structure of mitochondria with that of the chloroplasts.

Alpers Syndrome is an autosomal recessive disease caused by a mutation in the POLG gene, a gene which codes for a key mitochondrial protein. This mutation prevents replication of mitochondria, fundamentally impacting the function of muscle, nerves and the brain.

Suggest why Alpers syndrome affects these key organs in particular.

Alpers disease affects approximately 1 in 100 000 individuals. There are 68.35 million people in the UK.

Calculate the number of individuals in the UK with Alpers disease.

Identify the eukaryotic cell organelles and describe their structures by completing the table.

The ability to isolate organelles led to progress in the understanding of organelle structures and function.

(i) Describe the technique used to separate cellular organelles by size.

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(ii) Explain the order in which the organelles in the table in part (a) would be collected using the method described in part (i).

[1]

The pancreas is an organ responsible for the production of digestive enzymes which are secreted into the small intestines to break down molecules for absorption.

Describe the process carried out in pancreatic cells to prepare enzymes produced at the ribosomes, for secretion from the cell.

Pancreatic cells have adaptations that include many mitochondria.

Explain the role of mitochondria in the function of pancreatic cells as described in part (c).