M-STEP Science Assessment 5 — Questions and Answers
Question 1: Which best explains why some traits become more common in a population over many generations?
- Organisms choose to develop helpful traits
- Traits that help survival are more likely to be passed on (Correct answer)
- The environment directly changes DNA
- All traits are equally likely to be inherited
Correct answer: Traits that help survival are more likely to be passed on
Natural selection favors traits that improve survival and reproduction, making them more common over time.
Question 2: In an electrical circuit, which component is used to control the flow of electric current by opening or closing the circuit?
- Resistor
- Battery
- Switch (Correct answer)
- Capacitor
Correct answer: Switch
A switch opens or closes a circuit, either stopping or allowing electric current to flow.
Question 3: A student observes layers of sedimentary rock in a cliff. Which layer is most likely the oldest?
- The top layer
- The middle layer
- The bottom layer (Correct answer)
- All layers are the same age
Correct answer: The bottom layer
According to the law of superposition, in undisturbed rock layers, the bottom layer was deposited first and is oldest.
Question 4: Which process allows fish to obtain oxygen from water?
- They absorb oxygen through their skin
- They extract dissolved oxygen using gills (Correct answer)
- They breathe air at the water surface
- They produce their own oxygen through photosynthesis
Correct answer: They extract dissolved oxygen using gills
Fish use gills to extract dissolved oxygen from water as it passes over the gill filaments.
Question 5: When a light ray passes from air into glass, it slows down and bends. This bending of light is called:
- Reflection
- Diffraction
- Refraction (Correct answer)
- Absorption
Correct answer: Refraction
Refraction is the bending of light as it passes from one medium to another due to a change in speed.
Question 6: A student wants to test if salt affects the boiling point of water. Which variable should be kept the same throughout the experiment?
- Amount of salt added
- Volume of water used (Correct answer)
- Temperature of the water
- Number of trials
Correct answer: Volume of water used
The volume of water must be kept constant (controlled variable) to ensure a fair test when changing the amount of salt.
Question 7: Which best describes the role of decomposers in an ecosystem?
- They produce energy from sunlight
- They break down dead organisms and return nutrients to the soil (Correct answer)
- They convert nitrogen gas into protein
- They consume living plants for energy
Correct answer: They break down dead organisms and return nutrients to the soil
Decomposers like fungi and bacteria break down dead organic matter, recycling nutrients back into the ecosystem.
M-STEP Science Assessment 5
Which best explains why some traits become more common in a population over many generations?