E VOLUTION – THE BATTLE FOR SURVIVAL

T HE 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?

Y UCK ! 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?

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

V ARIATION AND C HARACTERISTICS

T HINK A BOUT T HE F OLLOWING... 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?

C HARACTERISTICS 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?

I NHERITED C HARACTERISTICS 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 her parents?

W HAT 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.

G ENETIC 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?

E NVIRONMENTAL C HARACTERISTICS 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.

I NHERITED OR E NVIRONMENTAL ? 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 Scars Natural hair colour Religion Tattoos Sporting ability Height Weight

O DD O NE O UT Hair ColourWeightBlood Group

O DD O NE O UT ScarsAccent Sporting ability

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

W HO 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.