Primary 5 · Science · Systems: Respiratory & Circulatory
Systems: Respiratory & Circulatory questions for Primary 5 Science
10 questions to work through online, 2 of them written out the way the paper asks. Answer and you get the working straight away, then a score at the end. No sign-up, and you can retake it as often as you like.
- Where blood is oxygen-rich
- Where blood is oxygen-poor
- What the heart does
- Reading exercise data
- Why blood must keep moving
- Reasoning about fitness
- Reasoning about smoking
- Naming the vessels
- Naming the exchange
- Applying the ideas
Same picture as the question above.
| Activity | Heartbeats per minute | Breaths per minute |
|---|---|---|
| lying down | 62 | 12 |
| walking | 88 | 19 |
| running | 150 | 35 |
Answers and explanations for all 10 questions
Every answer with the reasoning behind it. Worth reading after you have tried the set — or on its own, if you are a parent marking it.
In the diagram above, at which stage is the blood richest in oxygen?
Answer: Q
The blood collects oxygen in the lungs, so it is richest in oxygen on the way back from them, which is Q.
Using the same diagram, at which stage is the blood poorest in oxygen?
Answer: S
The body's cells take the oxygen out, so the blood returning from the body at S has least left.
Which two of these describe the heart's job?
Answer: A and B only
The heart pumps twice over: once to send blood to the lungs for oxygen, and once to send that oxygen-rich blood out to the body.
Based on the table above, which conclusion is correct?
Answer: The harder the activity, the faster both the heart and the breathing.
Both columns rise together — 62 to 150 and 12 to 35. Working muscles need more oxygen, so the body takes it in and delivers it faster.
Why must blood be pumped continuously rather than stored where it is needed?
Answer: It has to keep collecting oxygen and delivering it, over and over.
Oxygen is used up as fast as it arrives, so the blood has to return to the lungs for more. A supply that stopped moving would deliver nothing.
Two people run the same distance. One is fitter and her heart rate returns to normal much sooner. Which two statements are fair?
Answer: A and B only
A fitter person's heart and lungs move oxygen more efficiently, so the body catches up sooner. Recovery time is a standard way of measuring that.
Why does damage to the air sacs in the lungs leave a person short of breath?
Answer: There is less surface for oxygen to pass into the blood.
Oxygen crosses into the blood through the walls of the air sacs. Destroy some of them and there is less surface, so less oxygen gets through with each breath.
Blood travels around the body inside tubes of various sizes. What is the general name for these tubes? Blood ______ .
Answer: vessels
The tubes blood travels through are blood vessels.
In the lungs, oxygen goes into the blood and carbon dioxide comes out of it at the same time. This two-way swap is called gas ______ .
Answer: exchange
Oxygen in and carbon dioxide out at the lungs is gas exchange.
Athletes sometimes train at high altitude, where the air holds less oxygen. Why might this help them?
Answer: The body adapts to carry oxygen more effectively, which helps at normal altitude.
Short of oxygen, the body improves how well the blood carries what it gets. Back at normal altitude that improvement is still there, and now the air is richer.