Primary Science – Bacteria and Fungi

Mouldy Bread

This science revision note aims to help your child:

– understand how multiple concepts are tested in a single question (how can your child explain the answers accurately?

– the scientific keywords used in the mouldy bread experiment.

But before you read on, you might want to download this entire revision notes in PDF format to print it out for your child, or to read it later.

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Anna had 2 similar slices of bread. She sprayed equal amounts of water onto each piece of bread and placed them in different locations (Set-ups X and Y) as shown below.

After 2 days, Anna found that only one of the set-ups had mould.

Which set-up (X or Y) has mould? Explain your answer. (2m)

STEP 1

Since the question is asking which bread had mould, let’s consider what conditions allow mould to grow.

The conditions that allow mould to grow are:

Moisture
Warmth
Air (in P5 and P6 level science, the more accurate answer is Oxygen gas)

Note: As this is a 2 marks question, we need to apply two concepts: Evaporation and the relevant conditions that allow mould to grow.

STEP 2

Now consider which set-up (X or Y) provides the conditions stated above.

Moisture –> Anna dipped each slice of bread in water before leaving them in their respective locations.

Were both slices of bread able to keep their moisture?

The water in set-up X would gain heat from the sun and evaporate a lot faster to form water vapour. Hence, the bread under the sun was not able to keep its moisture and will become dry quickly.

The water in set-up Y would gain heat from the surroundings and evaporate a lot slower. Hence, the bread on the kitchen table was able to keep its moisture for a longer time.

Note: Take note of the scientific keywords used to explain the evaporation concept!

Warmth –> Although the heat from the sun is higher than that on the kitchen table, both set-ups provide warmth (as it is a sunny day, the room temperature in the kitchen will be quite high as well).

Warmth is thus not the important factor here that determines which bread grows mould.

Air (oxygen gas) –> Both set-ups have air and oxygen gas.

Hence, the air is not an important factor here that determines which bread grows mould.

STEP 3

So which set-up had the conditions necessary to grow mould?

Set-up Y.

FINALLY, answer the question.

After 2 days, Anna found that only one of the set-ups had mould.

Which set-up (X or Y) has mould? Explain your answer. (2m)

Answer:

Set-up Y. The water in set-up Y has a lower temperature. The water will gain heat from the surroundings and evaporate slower compared to set-up X. Hence, only the bread in set-up Y has moisture. (1m) Since mould requires moisture to grow, only set-up Y has the mould growing on the bread. (1m)

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