Microorganisms and Decay Worksheet

You might expect that microbes are all bad - but in fact they're not; amazingly, there are more 'good' types of microorganisms than 'bad' ones ('bad' ones are microbes that harm us).

One way in which different sorts of microbes are amazingly helpful is in the decay and decomposition (rotting) of things that have died, like a branch from a tree.

Basically, these microbes are nature's RECYCLERS, turning what was simply the remains of a living organism back into substances that can be used again and again. They're brilliant!

What do the billions of microorganisms in a pile of dead leaves feed on?

mud

leaves

water

What do the microorganisms in the pile of dead leaves break the leaves down into?

nutrients

oxygen

light

The process in which the microorganisms break down the pile of dead leaves is better known as what?

destruction

decomposition

fertilisation

Which TWO of the following are microorganisms which are found at work in a compost heap, helping to turn the dead plant material into soil?

viruses

bacteria

woodlice

fungi

Which of the following is NOT caused by bacteria?

tooth decay

mould on bread

turning milk into yoghurt

Why does brushing your teeth regularly help to prevent tooth decay?

brushing helps to remove the bad bacteria in our mouths

brushing helps to make our teeth shiny, helping them to resist bacteria

the toothpaste helps to make our teeth white

Here is a list of items and also a list of different ways you might dispose of them. Try to match the item to the best way of disposing of it in an environmentally friendly a way as possible.

Column A	Column B
newspaper	charity shop
drinks can	compost heap
children's books	recycling centre
dead flowers	recycling centre
uneaten meat scraps	recycling centre
plastic supermarket bag	recycling centre
old clothes, good condition	compost heap
potato peelings	charity shop
jam jar	throw in the bin
old batteries	use again

Nowadays, we are trying to make plastics that don't take hundreds of years to break down. These new plastics are damaged by exposure to light and usually decompose within 6 months or so. See if you can pick out the name of these sorts of plastics:

biodegradable

biological

bionic

Imagine that in a wood all the microorganisms that cause natural decay (rotting) where killed by a chemical spray. What do you think might happen as a result?

dead leaves and branches would become knee-deep

all the animals would leave the wood

plants would not die

ANSWERS

Question 1

What do the billions of microorganisms in a pile of dead leaves feed on?

CORRECT ANSWER

leaves

EDDIE SAYS

The dead leaves themselves are the microbes' food: they consume them (just like you consume a doughnut!) and recycle the leaves into simple chemicals that plants can use again.

ANSWERS

Question 2

What do the microorganisms in the pile of dead leaves break the leaves down into?

CORRECT ANSWER

nutrients

EDDIE SAYS

What was once dead leaf becomes important nutrients for living plants - that's recycling!

ANSWERS

Question 3

The process in which the microorganisms break down the pile of dead leaves is better known as what?

CORRECT ANSWER

decomposition

EDDIE SAYS

Decomposition is the proper term for when micro-organisms change dead organisms back into the chemicals they are made of.

ANSWERS

Question 4

Which TWO of the following are microorganisms which are found at work in a compost heap, helping to turn the dead plant material into soil?

CORRECT ANSWER

bacteria
fungi

EDDIE SAYS

Bacteria and fungi (moulds) are microbes that are hard at work inside the compost heap, consuming all those leaves, twigs and so on and recycling them for re-use by living plants so that they get back into the food chain.

ANSWERS

Question 5

Which of the following is NOT caused by bacteria?

CORRECT ANSWER

mould on bread

EDDIE SAYS

Mould is a type of fungus and so is not a type of bacteria.

ANSWERS

Question 6

Why does brushing your teeth regularly help to prevent tooth decay?

CORRECT ANSWER

brushing helps to remove the bad bacteria in our mouths

EDDIE SAYS

There are billions of bacteria on your teeth and over time they can damage your teeth and gums, so it is important to brush your teeth at least twice a day to remove the build-up of bacteria and protect your teeth.

ANSWERS

Question 7

Here is a list of items - which ones do you think can be broken down by microorganisms in less than a year?

EDDIE SAYS

Interestingly, micro-organisms are so efficient at decomposing dead organisms and reproduce so rapidly that most things in the list won't last a year. In fact a disposable nappy or a plastic bottle takes 400-500 years to break down!

ANSWERS

Question 8

Here is a list of items and also a list of different ways you might dispose of them. Try to match the item to the best way of disposing of it in an environmentally friendly a way as possible.

CORRECT ANSWER

Column A	Column B
newspaper	recycling centre
drinks can	recycling centre
children's books	charity shop
dead flowers	compost heap
uneaten meat scraps	throw in the bin
plastic supermarket bag	use again
old clothes, good condition	charity shop
potato peelings	compost heap
jam jar	recycling centre
old batteries	recycling centre

EDDIE SAYS

As you can see, many things you may generally throw away can be recycled. To be honest there are several in this list with more than one possibility, so give yourself a pat on the back if, for example, you said 'use again' to a jam jar - of course you can put homemade jam in it or use it as a pencil pot on your desk!

ANSWERS

Question 9

Nowadays, we are trying to make plastics that don't take hundreds of years to break down. These new plastics are damaged by exposure to light and usually decompose within 6 months or so. See if you can pick out the name of these sorts of plastics:

CORRECT ANSWER

biodegradable

EDDIE SAYS

BIODEGRADABLE means 'breaking down naturally', so man-made substances, like plastics, can be manufactured to degrade (break down) naturally in a much shorter time.

ANSWERS

Question 10

Imagine that in a wood all the microorganisms that cause natural decay (rotting) where killed by a chemical spray. What do you think might happen as a result?

CORRECT ANSWER

dead leaves and branches would become knee-deep

EDDIE SAYS

It's unthinkable! Imagine the dustmen went on strike - the bins wouldn't be emptied, rubbish would pile up on our streets. In the wood the leaves, twigs, dead mice, dead beetles, etc. would stay just like that, not breaking down - eventually the piles would just cover the ground everywhere!