Practice A2.1 Origins of cells (HL) with authentic IB Biology exam questions for both SL and HL students. This question bank mirrors Paper 1A, 1B, 2 structure, covering key topics like cell biology, genetics, and ecology. Get instant solutions, detailed explanations, and build exam confidence with questions in the style of IB examiners.
Paper
Level
Question 1
HLPaper 1A
Table showing that the codon UUU codes for phenylalanine in humans, yeast, and E. coli; also showing ribosomal RNA sequences conserved across these groups.
| Codon | Amino Acid | Human | Yeast | E. coli |
|---|---|---|---|---|
| UUU | Phenylalanine | ✓ | ✓ | ✓ |
| rRNA gene region | Sequence conserved | ✓ | ✓ | ✓ |
What does this genomic conservation provide evidence for?
Question 2
HLPaper 1A
Looking at the diagram, which feature was critical in simulating conditions on early Earth?
Question 3
HLPaper 1B
The figure shows a mechanistic sketch of how organic biomorphs (primitive pre-cellular structures) may have formed in a Miller-Urey-type simulation. The Miller-Urey experiment recreated early Earth conditions, including an alkaline soup rich in gases like CO2, CH4, NH3, and N2, exposed to electrical sparks mimicking lightning. This setup produced organic molecules like HCN (hydrogen cyanide), which accumulated over time and self-organized into spherical, caterpillar-like, and polyp-like protocells through polymerization processes.
1.[2]
List two key atmospheric conditions on early Earth that made spontaneous carbon compound formation possible, as modeled in the Miller-Urey experiment.
2.[2]
Based on the figure, describe the role of hydrogen cyanide (HCN) in forming early prebiotic structures.
3.[3]
Using the figure, compare the three morphologies (A, B, C) of biomorphs that formed over time. Provide one distinguishing feature for each.
4.[2]
Evaluate the Miller-Urey experiment as evidence for the origin of carbon compounds. Include one strength and one limitation.
Question 4
HLPaper 1A
The diagram shows RNA molecules catalyzing reactions. Why is RNA thought to be the first genetic material?
Question 5
SLPaper 1A
Which statement provides evidence for endosymbiosis?
Question 6
SLPaper 1A
The electron micrograph shows a section through a cell and refers to questions 1 and 2.
Which feature of the cell in the micrograph is consistent with the endosymbiotic theory?
Question 7
HLPaper 1A
What is evidence for the endosymbiotic theory?
Question 8
HLPaper 2
The RNA world hypothesis proposes that self-replicating ribonucleic acid (RNA) molecules were precursors to current life, which is based on deoxyribonucleic acid (DNA), RNA and proteins. It is generally accepted that current life on Earth descends from an RNA world, although RNA-based life may not have been the first life to exist.
1.[5]
Describe the role of RNA in early cellular life.
2.[5]
Describe main concepts of RNA-DNA evolution.
Question 9
HLPaper 2
1.[7]
Explain how the process of endosymbiosis led to the development of mitochondria and chloroplasts in eukaryotic cells.
Question 10
HLPaper 1A
The first iron ore deposits in rocks appeared about 1.8 billion years ago. What took place to make this occur?