Science in Punggol study guide · Article 0018 of 20

A system works through its parts and the connections between them. A fresh battery cannot light a torch if the circuit is broken; water in the soil cannot help a plant if its roots cannot take it up effectively.

Begin with the system’s function, then explain what each relevant part contributes.

On this page: Trace an electrical system · Connect plant parts to transport · Explain how human systems cooperate · Worked question: replacing a torch battery

Trace an electrical system

In a simple torch circuit, the battery supplies an energy source. Conducting connections form a path, the switch completes or breaks that path, and the bulb converts electrical energy into light and thermal energy.

The arrangement matters as much as the list of parts. A break in the conducting path can prevent the bulb from lighting even when the battery and bulb work.

Trace the path from one battery terminal, through the bulb, and back to the other terminal. Look for the actual gap before deciding which component needs changing.

This approach connects a part’s function to the result. It also avoids assuming that a new battery will solve every torch problem.

Connect plant parts to transport

Roots absorb water and mineral salts from the soil. Stems support plant parts and contain tissues that transport substances. Leaves make food through photosynthesis when the required conditions are available.

Water taken up by the roots must reach the leaves. Food made in the leaves can be transported to other parts that need it. These relationships explain why damage to one part can affect other functions.

Name what moves. Water, mineral salts and food have different origins and roles; the word “transport” alone does not explain the process.

For a plant diagram, use one set of arrows to show water moving from roots towards leaves. Use a separate diagram for food moving from leaves to other parts. Label the substance on each arrow.

Living systems also grow, reproduce and respond to their surroundings. Similarities with a circuit can help organise thinking, but they do not mean the systems use identical mechanisms.

Explain how human systems cooperate

The digestive system breaks food down so that digested food can be absorbed. The respiratory system allows oxygen to enter the body and carbon dioxide to leave. The circulatory system transports substances around the body.

Oxygen entering the lungs still needs to reach other body parts. Blood in the circulatory system provides that transport. The respiratory and circulatory systems cooperate while doing different jobs.

In a diagram, an arrow labelled “oxygen transported in blood” explains more than an unlabelled line between the lungs and the body. Connect the systems by naming both the substance and its movement.