Stanford Achievement Science Concepts Questions and Answers — Questions and Answers
Question 1: A student places a metal spoon in a cup of hot soup. After a few minutes, the handle of the spoon becomes warm. Which of the following best explains this phenomenon?
- Heat from the soup is transferred through the spoon by convection.
- The spoon produces its own heat in response to the soup.
- Heat from the soup is transferred through the spoon by conduction. (Correct answer)
- Warm air from above the soup heats the spoon handle by radiation.
Correct answer: Heat from the soup is transferred through the spoon by conduction.
Conduction is the transfer of heat through direct contact. The hot soup transfers thermal energy to the spoon's molecules, which then vibrate and transfer that energy along the length of the spoon to the handle.
Question 2: A scientist is testing the effect of different amounts of fertilizer on the height of tomato plants. Each plant is given the same amount of water and sunlight. What is the independent variable in this experiment?
- The height of the tomato plants.
- The amount of fertilizer used. (Correct answer)
- The amount of sunlight.
- The type of tomato plant.
Correct answer: The amount of fertilizer used.
The independent variable is the factor that the scientist intentionally changes or manipulates to observe its effect. In this case, the scientist is changing the amount of fertilizer to see how it affects plant height.
Question 3: In a forest ecosystem, which of the following is an example of a producer?
- A mushroom breaking down a dead log.
- A deer eating leaves from a bush.
- A snake eating a mouse.
- An oak tree making its own food using sunlight. (Correct answer)
Correct answer: An oak tree making its own food using sunlight.
Producers are organisms that create their own food, usually through photosynthesis. An oak tree uses sunlight, water, and carbon dioxide to produce its own energy, making it a producer at the base of the food web.
Question 4: Which of the following is a primary requirement for the process of photosynthesis to occur?
- Oxygen
- Soil
- Carbon Dioxide (Correct answer)
- Glucose
Correct answer: Carbon Dioxide
Photosynthesis is the process where plants use sunlight, water, and carbon dioxide to create their own food (glucose) and release oxygen as a byproduct. Therefore, carbon dioxide is a necessary reactant, or input, for the process to begin.
Question 5: After a rainstorm, a puddle of water on the sidewalk disappears over a few hours on a sunny day. This process is known as:
- Condensation
- Precipitation
- Transpiration
- Evaporation (Correct answer)
Correct answer: Evaporation
Evaporation is the stage of the water cycle where liquid water turns into water vapor (a gas) and rises into the atmosphere. The sun's heat provides the energy for this process to occur, causing the puddle to 'disappear'.
Question 6: Which of the following is an example of physical weathering?
- Acid rain dissolving the surface of a limestone statue.
- Iron in a rock rusting and turning reddish-brown.
- Water freezing in the crack of a rock and splitting it apart. (Correct answer)
- A lichen releasing chemicals that break down a rock's minerals.
Correct answer: Water freezing in the crack of a rock and splitting it apart.
Physical (or mechanical) weathering is the process of breaking down rocks into smaller pieces without changing their chemical composition. When water freezes, it expands, exerting force on the rock and causing it to crack and break apart.
Stanford Achievement Science Concepts Questions and Answers
A student places a metal spoon in a cup of hot soup.
After a few minutes, the handle of the spoon becomes warm.
Which of the following best explains this phenomenon?