EVOLUTION – THE BATTLE FOR SURVIVAL

THE BIG QUESTIONS

In the past we have had a lot of questions that we did not have answers to: Why do giraffes have long necks? Why do zebras have stripes? Why do caterpillars taste so bad?

YUCK!

Look at this caterpillar.

How do you think it happened that he is so disgusting to eat?

What caused him to taste so bad? Anybody got any theories? Ideas?

EVOLUTION

Did the caterpillar think about it? Make the decision for itself? Or did it just happen over time?

VARIATION AND CHARACTERISTICS

THINK ABOUT THE FOLLOWING...

What do you think the word “characteristic” means?

Have a look at the person next to you. Can you identify some of their

characteristics?Are they the same as yours or

different?

CHARACTERISTICS A characteristic is a feature of an organism. It

can be something we can see (like hair colour) or something we can’t see (like blood group).

All humans have different combinations of characteristics, meaning we all look different.

This difference in our characteristics is called variation.

Your family tree.

What characteristics have passed

down the generations in your family?

INHERITED CHARACTERISTICS These are features that we get passed down to

us from our parents.

They are coded for by genes – little bits of DNA in our cells’ nucleui.

We get half of our genes from our mother and half from our father because the nuclei of their sex cells fuses together in fertilisation.

The Mr Men Match.

Meet our Mr Men and our Little Misses

Now let’s meet their children!

Who do you think are his parents?

Who do you think are her parents?

Who do you think are his parents?

Who do you think are his parents?

Who do you think are her parents?

Who do you think are her parents?

WHAT DID WE LEARN FROM THIS?

Children inherit features from their parents

If two parents have a certain characteristic then their child may show it even more (e.g. Mr Small + Little Miss Tiny = Mr Very Small!)

Some things such as glasses, scars and muscles we get from our environment, they are not inherited.

GENETIC INFORMATION

The instructions that make up a plant or animal comes from their parents.

½ comes from the male and ½ from the female These instructions are found in the nucleus of the

cells. The instructions for each characteristic are called

GENES.

We saw that when Mr Small and Little Miss Tiny produced a child it was even smaller.

What would happen if Mr Very Small had a child with Little Miss Miniscule??

Are all of our characteristics

inherited?

ENVIRONMENTAL CHARACTERISTICS Some of our features are determined by how we

live and the choices we make, for example what we eat and where we live.

These are environmental characteristics

Some characteristics can be both, for example height and weight.

INHERITED OR ENVIRONMENTAL? Have a look at the list of characteristics below. Decide in pairs whether they’re inherited,

environmental or both.

Accent

Eye Colour

Blood group

Sex

Tongue rolling

Nose shape

ScarsNatural hair colour

ReligionTattoos

Sporting ability

Height

Weight

ODD ONE OUT

Hair Colour Weight Blood Group

ODD ONE OUT

Scars Accent Sporting ability

IF IDENTICAL TWIN BROTHERS MARRIED IDENTICAL TWIN SISTERS, WOULD ALL THEIR CHILDREN LOOK THE SAME?

?

WHO DO YOU AGREE WITH?All the children

would look identical.

All the children would look completely

unalike from each other.

The children would have some

similarities but still differ.

The children have an equal

chance of looking the same or

different.

Everyone has dominant and recessive genes... meaning we all have genes that we don’t outwardly show but can still be past down to our offspring that they can show. Both couples would pass down different dominate/recessive genes to their offspring which would make each child different. It just depends on what genes the parent gives their child... dominate or recessive.

The children

would have some

similarities but still differ.