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Primary 5 Science for September - Air and the Respiratory System

Updated: Feb 3, 2023

Here's what students can expect for Primary 5 Science for the month of September.

The school would be heading to a topic on Air and the Respiratory System. This topic is a related to the topic on body systems which students have learnt in P4. This topic is concept heavy thus students are required to remember multiple concepts.

For this topic students are required to recognise that air is a mixture of gases such as nitrogen, carbon dioxide, oxygen and water vapour, not only that, students have to know the proportion of different gasses in our atmosphere shown in the table here:

Other than knowing about the proportions, students have to know some of the basic usage of the gases as shown in the table below:

As there will be experiment questions relating to this topic, students are also required to know how to identify the different type of gases present in the experiment.

  • Presence of oxygen can be identified by burning a substance. When oxygen is present, a glowing splint will rekindle.

  • Presence of carbon dioxide can be identified by bubbling it through limewater. When carbon dioxide is present, the limewater will turn milky or chalky.

Students not only have to know about the gases in the atmosphere, they have to know about an important process called respiration. Respiration is the process in which living things take in oxygen to break down digested food and produce energy. During respiration, carbon dioxide is given out.

Another concept they have to be sure of, is the different breathing methods of different organisms which were mentioned in their lower block and shown in the table here.

Next, students have to know the organs and its function of the human respiratory system as shown here.

It is crucial that students know how the human respiratory system works during exhaling and inhaling shown in the table here.

Students have to remember all the concepts mentioned earlier to score well for this topic.

Most questions on Air and respiratory system requires knowledge recall and applying concepts to explanation questions.

Let’s look at the question shown here.

For part (a), students have to use their science concept that during exercising, more energy will be required thus will respire faster. Since graph A shows a higher volume of air taken in, and taking a shorter time for a breath comparing to graph B, it indicated that breathing rate is faster, resulting in faster respiration. Graph A will be the correct answer. For part (b), students are supposed to answer based on the explanation answering technique, since there are no results provided in the question. There are 2 steps: (Observation) When Ni Le exercised, his body needed more energy (science concept). He breathes faster and deeper to take in more oxygen and remove more carbon dioxide for his muscles to undergo a higher rate of respiration to release more energy.

Students are required to have at least 2 steps for such explanation question and they have to memorise the concepts for this topic of respiratory system in order to relate it to different question types.


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