Science 8 - Assignment Answer Key

Systems in a Organism

Total Marks: 34

1.

1. C
2. A
3. C
4. B
5. B

(5 marks)

2. D (1 mark)

3. A (1 mark)

4. C (1 mark)

5. A high-fat diet may lead to fat deposits in your blood vessels. Such a blockage restricts the blood flow. This may cause a heart attack. (2 marks)

6. D (1 mark)

7. Accept any plausible reason. A sample answer follows. Compared to men, more women started smoking in the period from 1965 to 1995. (2 marks)

8. Smoking kills the ciliated cells and destroys the cilia. Without the cilia, the dirt and bacteria are not removed effectively. This means the passages are not as clean as they would otherwise be. (2 marks)

9. Healthy lifestyle choices include the following:

• Don’t smoke.
• Eat a healthy, well-balanced, high-fibre diet that’s low in salt and fats.
• Exercise regularly.
• Get plenty of sleep.
• See a doctor before a problem becomes too serious.
• Get immunized.
• Avoid environmental toxins and pollutants.
• Avoid long-term emotional stress.
• Avoid excessive use of alcohol or aspirin.

(4 marks)

10.

1. The kidneys are classified as an organ. (1 mark)
2. A dialysis machine removes waste materials from blood. (1 mark)
3. It is semipermeable. (1 mark)
4. Wastes move out of the blood. The process is classified as osmosis (or diffusion). (2 marks)
5. Salt and glucose are in balance. (1 mark)
6. The dialysis membrane is impermeable. (1 mark)

11.

1. The cytoplasm of an amoeba has a function that’s similar to the circulatory systems of a human.
2. The cell membrane of an amoeba has a function that’s similar to the skin of a human.
3. The nucleus of an amoeba has a function that’s similar to the nervous system of a human.

(3 marks)

12.

a. Specific functions of the circulatory system include the following:

• transports oxygen to cells
• transports waste carbon dioxide to lungs
• transports hormones throughout the body
• transports nurtrients to the cells
• transports water to the cells
• transports cellular waste products to the kidneys
• transports cells and chemicals that help repair injuries and fight disease
• connects all other organ systems

(1 mark for each of three functions)

13.

1. The respiratory system and the circulatory system are the most closely connected. (1 mark)
2. The digestive system and the circulatory system are the most closely connected. (1 mark)