As you walk past a park, have you ever wondered what happens to the fallen leaves, branches, and flowers scattered on the ground? They won’t just sit there forever but instead, they will slowly break down, thanks to a group of organisms called decomposers.
Decomposers are like nature’s hidden cleanup crew! But what exactly do they do, and why are they so important?
Let’s find out more about decomposition!
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What is Decomposition?
Decomposition is the process in which dead matter is broken down into simpler substances. These simpler substances are then returned to the soil as mineral salts and nutrients, where plants can absorb them for their growth.
Let’s examine this question on Decomposition: 2023/ Primary 6/ Prelims/ Ai Tong School
30. Alvin put some dead leaves and a small amount of damp soil in a glass jar as shown below.
He used a thermometer to measure the changes in temperature as the leaves decay over a period of time.
(a) State two conditions needed for decomposition to take place. [1]
(b) State the two products that are given out during decomposition. [1]
Bird Z buries its eggs underground. The eggs are placed on top of decaying leaves and covered with sand.
(c) Based on Alvin’s experiment, explain why the birds lay its eggs underground, on top of the decaying leaves. [1]
(d) Suggest another advantage of burying eggs underground. [1]
Let’s break down parts (a) and (b)
Before we look at the conditions needed for decomposition, let’s first find out who the decomposers are. Do you remember which organisms help break things down?
That’s right – Fungi and Bacteria!
For fungi and bacteria to thrive, they need three things: Water, Oxygen, and Warmth – or just remember W.O.W! These conditions will help decomposition happen faster. During this process, dead plants and animals are then broken down into nutrients that go back into the soil. Plants can then take in these nutrients to grow. Also, carbon dioxide is released during decomposition. We are now ready to answer parts (a) and (b)!
Proposed/Suggested Answer for parts (a) and (b)
(a) Oxygen/Warmth/Water (Any two)
(b) Carbon dioxide and water vapour
Let’s break down parts (c)
From Alvin’s graph, we can see that the temperature increases over time. Hence, we can conclude that heat is released during the process of decomposition.
But how does this relate to the eggs?
Do you remember how a mother hen sits on her eggs to keep them warm so they can hatch? This is also known as incubation, to keep the eggs warm such that they can hatch. In this case, the heat from decomposition helps keep bird Z’s eggs warm—so the parent doesn’t need to sit on them.
Proposed/Suggested Answer for parts (c)
(c) When the leaves decompose, heat [energy] is released. The heat helps to keep the eggs warm/ the eggs continue to gain heat so the eggs can hatch faster.
Let’s break down parts (d)
If you look closely at the diagram, you’ll notice that the eggs are hidden by the sand. This makes it harder for predators to find them, keeping the eggs safe and protected from being eaten. As such, this increases the chances of eggs hatching into young and developing into adults!
Proposed/Suggested Answer for parts (d)
(d) Predators are less likely to spot and eat the eggs hence increasing the chances of eggs hatching and developing into young.
Key Takeaways of Decomposition
In conclusion, decomposition plays a vital role in the ecosystem by breaking down dead matter and recycling nutrients back into the environment. Thanks to decomposers like fungi and bacteria—and the right conditions of Water, Oxygen, and Warmth (W.O.W!)—this natural process supports life all around us. 🌱
We also learned that decomposition can produce heat, which in special cases (like with Bird Z’s eggs!) supports animal adaptation. This question tested knowledge across multiple topics—but with the right skills to break it down, it’s absolutely conquerable!
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