IB MYP Integrated Sciences e-Assessment : Cells, tissues, organs, and systems Exam Style Practice Questions - New Syllabus
Question (9 marks)
Athletes need to exercise daily and follow a strict dietary regime to perform at the highest levels. As a result of their exercise and dietary routines, athletes have increased muscle mass compared to people who do not exercise. An image of the body can be seen below:
Question (1 mark)
Topic Code: Cells, Tissues, Organs, and Systems
Select the correct term to describe the level of organization shown in the image:
- [ ] Vacuole
- [ ] Organelle
- [ ] Molecule
- [ ] Organ system
▶️Answer/Explanation
Answer: Organ system
Explanation: The image shows a human body, which is an example of an organ system. Organ systems are composed of multiple organs working together to perform a specific function, such as the muscular system or the digestive system.
Question (2 marks)
Topic Code: Cells, Tissues, Organs, and Systems
The diagram below shows a single muscle cell. Label the structures found in the muscle cell below:
Draggable items:
- Cell membrane
- Mitochondria
- Chloroplast
- Ribosomes
- Nucleus
- Cytoplasm
▶️Answer/Explanation
Answer:
– Ribosomes
– Nucleus
– Mitochondria
Explanation: According to the markscheme, the correct structures to label in the muscle cell are ribosomes, nucleus, and mitochondria. Ribosomes are involved in protein synthesis, the nucleus controls cell activities, and mitochondria produce energy (ATP) through cellular respiration. Chloroplasts are not found in animal cells, and while the cell membrane and cytoplasm are present, they are not the focus of this question.
Question (4 marks)
Topic Code: Cells, Tissues, Organs, and Systems
The number of mitochondria differs from one cell type to another. The table below shows the mean number of mitochondria per cell in different types of cells.
| Cell type | Mean number of mitochondria |
|---|---|
| Fat cell | 100 |
| Skin cell | 200 |
| Muscle cell | 1700 |
Suggest and justify a reason for the difference in the mean number of mitochondria found in muscle cells compared to fat and skin cells. You should use scientific terminology in your answer.
▶️Answer/Explanation
Answer:
Muscle cells require a high amount of energy for contraction and movement, which is provided by cellular respiration in the mitochondria. Therefore, muscle cells have more mitochondria compared to fat and skin cells, which have lower energy demands.
Explanation:
Mitochondria are the powerhouses of the cell, producing ATP through cellular respiration. Muscle cells are highly active and require constant energy for movement, leading to a higher number of mitochondria. Fat cells store energy, and skin cells have a protective function, both of which require less energy compared to muscle cells.
Question (2 marks)
Topic Code: Digestion
It is recommended that athletes consume large amounts of protein to maintain their muscle mass. Digestion of protein starts in the stomach. The graph below shows the activity of different digestive enzymes at different pH levels. Select the graph that represents the enzyme responsible for the initial digestion of protein. Justify your answer.
▶️Answer/Explanation
Answer: Graph A
Justification: The stomach has a low pH (acidic environment), and the enzyme pepsin, which digests protein, is most active in acidic conditions. Therefore, the graph showing high enzyme activity at low pH represents the enzyme responsible for protein digestion.
Explanation:
Pepsin is the enzyme that breaks down proteins in the stomach, and it functions optimally at a pH of around 2, which is highly acidic. This matches the conditions in the stomach, where protein digestion begins.