Passing Down Characteristics from Parents to Young

Here is something to think about. Your classmate has the same wavy hair as her mum. Your friend has the same dark-brown eyes as his dad. But nobody in your school was born already knowing how to speak English or swim freestyle — they had to learn those things. So why do some features travel from parents to children, while others do not? That is exactly what PSLE Science wants you to understand, and once you do, you will never mix up these two very different types of characteristics again.

Parents: the interactive sim in the middle of this page asks your child to decide whether each trait is inherited or not — encourage them to commit to an answer before tapping to reveal. Let them explain their reasoning out loud. The "Teacher's tip" boxes name the precise keyword the PSLE marker is looking for.

By the end you will be able to identify inherited characteristics, explain why young resemble but are not identical to their parents, and sort out which traits are NOT inherited. There are four ideas to master: what inherited characteristics are, how young resemble but differ from parents, what makes a characteristic "not inherited," and how inheritance works in plants as well as animals.

What are inherited characteristics?

Think of your genes as a recipe book passed down by your parents. Half the recipe comes from your mother, half from your father. The features that get written into that recipe — things like your natural hair colour, your eye colour, the shape of your nose — are called inherited characteristics.

An inherited characteristic is one that a young organism receives from its parents through reproduction. You do not have to do anything to get it — you are born with it already. A cat is born with its fur pattern. A sunflower seedling already carries the gene that will make its petals yellow. A puppy is born with the same pointed ears as its mother. None of them learned or earned these features. They were passed down.

Young resemble their parents — but are not identical

Here is the second idea, and it trips up many students. Young organisms look like their parents, but they are not exact copies.

Think about a litter of kittens. All of them have the same pointed ears and soft fur as their mother, but each kitten has a slightly different fur pattern. Or consider a mango tree and the seedlings that grow from its seeds — each seedling will grow mangoes, but the shape and sweetness may vary slightly from tree to tree. The young received genes from TWO parents (or, in plants that reproduce sexually, from two parent plants), so the combination is always a little different.

This is why you might have your mother's eye colour but your father's nose shape — you are a unique mix of both.

Characteristics that are NOT inherited

Not every difference between you and your parents came from genes. Some characteristics develop because of what happens to you during your lifetime. These are called acquired characteristics (also called learned or environmental characteristics), and they are not inherited.

Here are the three main ways a characteristic can be acquired:

• Injury — a scar on your knee from a bicycle fall. Your children will not be born with that scar.
• Learning and practice — the ability to speak Mandarin, play piano, or swim freestyle. You earned these skills through effort, and they stay with you, not your genes.
• Environment — a suntan from spending holidays at East Coast Park. Your skin colour changed because of sunlight, not because of your genes. Your children will be born with their own original skin tone.

The key test is this: Did the organism do something, learn something, or have something happen to it? If yes, the characteristic is almost certainly not inherited.

Now sort a set of traits in the sim below. Predict the trickiest one first.

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Inherited or not? Sort each trait

🤔 Predict first: Is a scar on your knee passed down to your children?

YesNo

Inheritance in plants

Animals are not the only ones that pass characteristics to their young. Plants do it too, in exactly the same way.

A red hibiscus plant passes its red petal colour to its offspring. A tall pea plant produces seeds that grow into tall plants. A cactus produces offspring with the same thick, waxy skin for holding water. These are all inherited characteristics in plants.

And just like animals, plants can also have changes that are NOT inherited. If a plant is grown in the dark, its leaves may turn yellow from lack of sunlight. But a seed from that same plant, grown in good light, will produce healthy green leaves — because the yellowing was environmental, not written into the genes.

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Plant or animal — inherited or not?

🤔 Predict first: A bonsai tree is kept very small by pruning. Will its seeds grow into small trees too?

Yes — the small size is inheritedNo — the small size is not inherited

Watch out — these are easily mixed up

Quick recap

🎯 Mastery check

Answer all 8 — your progress is saved on this device.

1. A girl has the same brown eyes as her father. What type of characteristic is this?

   An acquired characteristic, because the environment made her eyes brownAn inherited characteristic, because it was passed from her father to herA learned characteristic, because she practised having brown eyes

2. Amir broke his arm and it healed with a small bump. Will his children be born with the same bump on their arm?

   Yes, because the characteristic will be inheritedNo, because the bump is an acquired characteristic caused by injury and cannot be passed to offspringYes, but only if they also break their arm

3. A litter of kittens all have pointed ears like their mother, but their fur patterns are slightly different from each other. Why?

   The kittens inherited characteristics from both parents, so each kitten has a unique combinationThe kittens learned their fur patterns after birthThe fur patterns were caused by different environments

4. A sunflower plant is kept in a dark room. Its leaves turn yellow. A seed from this plant is grown in bright sunlight. What colour will its leaves be?

   Yellow, because it inherited the yellowing from its parentGreen, because the yellowing was an environmental change and not inheritedIt depends on how much water it receives

5. Which of the following is an example of an inherited characteristic in animals?

   A scar on a dog leg from a fightThe ability of a parrot to say "hello" after trainingThe striped coat pattern of a zebra

6. A farmer selects the tallest pea plants and collects their seeds. He plants those seeds next season. Why might the new plants also tend to be tall?

   The seeds absorbed nutrients from the tall plantsHeight is an inherited characteristic passed from parent plants to offspringThe environment made them tall automatically

7. Maya learned to play the violin at school. Her baby brother is just born. Can he play the violin already?

   Yes, because the skill is inherited from MayaNo, because playing the violin is a learned skill — it is not an inherited characteristicYes, but only if he practises later

8. A student says: "Because a whale and a dog both have fur, they must both have fur-coloured young." Is this correct, and why?

   Yes, because fur colour is always the same within a speciesNo — young inherit a unique combination from both parents, so fur colour in offspring may varyNo — fur colour is an acquired characteristic caused by environment

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