AZSCI Scale, Proportion, and Quantity 2 — Questions and Answers
Question 1: A scientist is comparing the size of a virus (about 100 nm) to a human cell (about 10 µm). Approximately how many times larger is the human cell than the virus?
- 100 times larger (Correct answer)
- 10 times larger
- 1,000 times larger
- 10,000 times larger
Correct answer: 100 times larger
10 µm = 10,000 nm; 10,000 nm ÷ 100 nm = 100, so the human cell is 100 times larger than the virus.
Question 2: A car travels 300 km in 3 hours at a constant speed. What is the proportional relationship between distance and time?
- 100 km per hour (Correct answer)
- 900 km per hour
- 1 km per 3 hours
- 30 km per hour
Correct answer: 100 km per hour
300 km ÷ 3 hours = 100 km/hour; this constant ratio represents a directly proportional relationship.
Question 3: Which tool would a scientist use to accurately measure the mass of a small rock sample?
- Balance scale or digital balance (Correct answer)
- Ruler
- Graduated cylinder
- Thermometer
Correct answer: Balance scale or digital balance
Mass is measured using a balance or digital balance, which detects or compares the gravitational force on an object.
Question 4: In an experiment, doubling the concentration of a reactant doubles the reaction rate. This relationship is best described as:
- Directly proportional (Correct answer)
- Inversely proportional
- Exponential
- Independent
Correct answer: Directly proportional
When one quantity doubles and the other doubles as well, they share a directly proportional (linear) relationship.
Question 5: What is the primary reason scientists worldwide use the International System of Units (SI)?
- To ensure measurements are consistent and comparable across labs and countries (Correct answer)
- To make calculations harder for students to understand
- Because it is required by law in the United States only
- To avoid using very large or very small numbers
Correct answer: To ensure measurements are consistent and comparable across labs and countries
Standard SI units ensure that measurements can be reliably reproduced and compared by scientists anywhere in the world.
Question 6: Which of the following demonstrates proportional thinking in an ecological context?
- If the prey population doubles, the predator population is expected to increase proportionally (Correct answer)
- If the temperature rises 1°C, all populations will exactly halve
- If one species goes extinct, all other species are unaffected
- If rainfall doubles, all desert regions become forests
Correct answer: If the prey population doubles, the predator population is expected to increase proportionally
Predator-prey relationships often show proportional trends because more available prey can support a proportionally larger predator population.
Question 7: A student graphs the growth of a plant over 5 weeks. The plant grew 2 cm per week consistently. Which statement best describes the proportional relationship?
- Total growth is directly proportional to the number of weeks (Correct answer)
- Total growth is inversely proportional to the number of weeks
- Growth rate increases each week proportionally
- There is no proportional relationship because living things are unpredictable
Correct answer: Total growth is directly proportional to the number of weeks
A constant growth rate of 2 cm/week means total growth = 2 × weeks, which is a direct proportion.
AZSCI Scale, Proportion, and Quantity 2
A scientist is comparing the size of a virus (about 100 nm) to a human cell (about 10 µm).
Approximately how many times larger is the human cell than the virus?