Scientists use this name for a fallen tree that helps other organisms live and grow.
What is a nurse log?
This is a group of parts that interact with one another.
What is a system?
Scientists can measure a plant’s change in this to track how much matter it gains as it grows.
What is weight?
In a fair test, scientists intentionally change only one of these at a time.
What is a variable?
This is anything that has weight and takes up space.
What is matter?
Moss, insects, fungi, and young plants may all be found in, on, or around this forest feature.
What is a nurse log?
Each individual part of a system is called this.
What is a component?
Plants get most of the material they need for growth from these two sources.
What are air and water?
Conditions that scientists keep the same during an investigation are called these.
What are controlled variables?
Sunlight is this—not matter.
What is energy?
A nurse log provides living things with these two things needed for life and growth.
What are matter and energy?
In the nurse log system, this small plantlike organism was closely observed during Lesson 2.
What is moss?
Plants take in water mainly through these structures.
What are the roots?
Scientists use these kinds of trials to make their results more reliable.
What are repeated trials?
Air is this state of matter made of tiny particles moving freely through space.
What is a gas?
Before becoming a nurse log, the living tree used sunlight to make and store this type of food.
What is sugar?
Arrows in a scientific model are often used to show these between the components of a system.
What are interactions or movements of matter and energy?
Plants can grow without this material, although it can provide support, water, and nutrients.
What is soil?
Students test whether light affects plant growth. Name one condition they should keep controlled.
Responses vary: plant type, amount of water, container size, soil, starting size, or length of the investigation.
A plant is called this because it makes its own food using energy from the Sun.
What is a producer?
Explain two ways a nurse log can help a young plant live and grow.
It can provide water, matter, a place to grow, and access to sunlight or stored matter. Accept any two supported ideas.
Name three components of a nurse log system and describe one interaction among them.
Responses vary. Example: A nurse log, moss, and water are components. The moss absorbs water from the nurse log system.
A plant gains weight as it grows. Explain where most of that added matter comes from.
It comes chiefly from particles of air and water taken into the plant.
One plant is placed in sunlight and watered daily. Another is placed in darkness and receives no water. Explain why this is not a fair test.
Two variables—light and water—were changed, so scientists cannot determine which variable caused the result.
Explain why air and water are matter, but sunlight is not matter.
Air and water have weight, take up space, and are made of particles. Sunlight is energy and does not have weight or take up space.