AzM2 Science Assessment 1 — Questions and Answers
Question 1: Which of the following BEST describes the role of producers in an ecosystem?
- They consume other organisms for energy
- They break down dead matter into nutrients
- They convert sunlight into food through photosynthesis (Correct answer)
- They transport nutrients through the food web
Correct answer: They convert sunlight into food through photosynthesis
Producers (plants, algae) use photosynthesis to convert sunlight, water, and carbon dioxide into food (glucose), forming the base of all food chains.
In ecosystems: Producers (C) are autotrophs that make food via photosynthesis — they are the foundation of food webs. Consumers (A) eat other organisms. Decomposers (B) break down dead matter. There is no 'nutrient transport' organism (D). The sun's energy flows from producers to primary consumers to secondary consumers, etc. Answer C is correct.
Question 2: A student drops a ball from different heights and measures how high it bounces. What is the INDEPENDENT variable in this experiment?
- The height from which the ball is dropped (Correct answer)
- The height the ball bounces
- The type of surface the ball lands on
- The mass of the ball
Correct answer: The height from which the ball is dropped
The independent variable is what the student intentionally changes. The student changes the drop height, so that is the independent variable.
Scientific method variables: Independent variable (A) = what the experimenter deliberately changes (drop height). Dependent variable = what is measured in response (bounce height = B). Constants = kept the same (surface type, ball mass). The independent variable is the 'cause,' the dependent variable is the 'effect.' Answer A is correct.
Question 3: Water changes from liquid to gas during evaporation. What type of change is this?
- Chemical change, because a new substance is formed
- Physical change, because the water molecules remain H₂O (Correct answer)
- Nuclear change, because atoms are rearranged
- Biological change, because it happens in nature
Correct answer: Physical change, because the water molecules remain H₂O
Evaporation is a physical change — the water changes state (liquid to gas) but the molecules remain H₂O. No new substance is created.
Physical changes alter form but not chemical composition. During evaporation, H₂O molecules remain H₂O — only the phase changes from liquid to gas. No new substance is created. This is a physical change (B). Chemical changes (A) create new substances (e.g., burning). Nuclear changes (C) involve atoms' nuclei. 'Biological change' (D) is not a scientific category for matter changes. Answer B is correct.
Question 4: The Earth's layers from outermost to innermost are:
- Core, mantle, crust
- Crust, mantle, outer core, inner core (Correct answer)
- Mantle, crust, core
- Inner core, outer core, crust, mantle
Correct answer: Crust, mantle, outer core, inner core
Earth's layers from outside to inside: crust (solid rock), mantle (hot, flowing rock), outer core (liquid iron/nickel), inner core (solid iron/nickel).
Earth's interior structure (outside → inside): Crust → Mantle → Outer Core → Inner Core. Answer B lists them correctly. The crust is the thin, solid outer layer. The mantle is the largest layer (mostly solid with some molten rock). The outer core is liquid iron/nickel. The inner core is solid despite extreme heat due to immense pressure. Answer B is correct.
Question 5: Which process in the water cycle returns water from the atmosphere to the Earth's surface?
- Evaporation
- Condensation
- Precipitation (Correct answer)
- Transpiration
Correct answer: Precipitation
Precipitation (rain, snow, sleet, hail) returns water from clouds in the atmosphere to Earth's surface.
Water cycle processes: Evaporation (A) = liquid water becomes water vapor (surface → atmosphere). Condensation (B) = water vapor forms clouds (still in atmosphere). Precipitation (C) = water falls from clouds to Earth's surface as rain, snow, etc. Transpiration (D) = plants release water vapor. Only precipitation (C) returns water from the atmosphere to the surface. Answer C is correct.
Question 6: A scientist observes that plants in a shaded area are shorter than plants of the same species in a sunny area. What is the MOST reasonable explanation?
- Shaded plants receive more water
- Sunlight is needed for photosynthesis, which provides energy for growth (Correct answer)
- Shaded plants have different genetics
- The shade causes the soil to become less fertile
Correct answer: Sunlight is needed for photosynthesis, which provides energy for growth
Sunlight drives photosynthesis, which produces the energy (glucose) plants need to grow. Less light means less photosynthesis and slower growth.
Plants use sunlight for photosynthesis to produce glucose — their energy source for all life processes including growth. Less sunlight → less photosynthesis → less energy → slower growth → shorter plants (B). Answer A is incorrect — shade doesn't necessarily mean more water. Answer C is possible but not the most direct/reasonable explanation given the information. Answer D is a secondary and less direct effect. Answer B is the most scientifically direct explanation.
