1. INHERITANCE & SELECTION
In This Section We Will Be Studying The Following Topics:
Inheritance of characteristics.
Variation within a species.
Fertilisation.
Selective breeding in plants.
Selective breeding in animals.
Farming and industries that use selection.
Cloning.

2. WHY DO WE LOOK LIKE OUR PARENTS?
The way we look is determined by our characteristics.
Our characteristics are coded for by our genetic information and this comes from our parents.
Egg Cell (ovum).
Sperm Cell.
This type of reproduction where genetic information is shared is called SEXUAL REPRODUCTION.
The genetic information from both parents gives us our individuality. We cannot be identical to either of our parents but we can look a little like both of them.

3. FERTILISATION When a sperm has fertilised an egg a zygote is formed.
The zygote will divide and grow into an embryo. This will grow into a baby.
Twins are formed when the fertilised egg divides into two before it starts to divide into a baby. This is how identical twins are produced. They are genetically identical to each other.
If 2 different sperm fertilise 2 different eggs FRATERNAL twins will be produced but they will not be genetically identical. They can be different sexes and they will look different.

4. GENES
Our cells contain our genetic information inside their nucleus.
We inherit half of our genetic information from our mother and half from our father.
The genes are small sections of DNA that code for particular characteristics.
This is a picture of sperm being added to an egg cell. This allows the two sets of chromosomes to meet.
When humans have problems with fertilisation it can be done in a laboratory and the fertilised egg can be implanted back into the female.

5. GENES
Genes are found in the tightly bound chromosomes of all cells. They are pieces of code.
We inherit 23 chromosomes from our mother.
We inherit 23 chromosomes from our father.
Our cells have 46 chromosomes all together.

6. ENVIRONMENTAL VARIATION
Environmental variation can be affected by your culture and the country you live in.
How many examples of this sort of variation can you think of?
There are far too many to name!
Even the type of music or dance we enjoy can be affected by the environment we live in.

7. ENVIRONMENTAL VARIATION
We might make permanent changes to our appearance by surgery i.e. face lifts.
We might tattoo or pierce our bodies.
We may change our weight.
These may be done to ‘fit in with’ the environment or even to keep in with a fashion.
Would tattoos be seen on an Inuit Indian?

8. INHERITED VARIATION
Inherited variation is caused by the genes mixing and they always make a new individual. The new individual may look like the parents but it is UNIQUE.
Did you know that there are White tigers? They are rare.
They can survive well in the snow as they have better CAMOUFLAGE than orange tigers.

9. INHERITED or ENVIRONMENTAL?
Inherited or environmental? Which statement is which?
Variation that is influenced
by living conditions and surroundings.
Variation that comes from the
genes passed on from
parent to offspring.
Inherited variation Environmental variation

10. VARIATION Variation. Inherited. Environmental. Both.
Look at the characteristics listed below. Which are inherited variation and which are environmental variation?
Variation.
Inherited.
Environmental.
Both.
Blood group.
Skin colour.
Height.
Tongue rolling.
Dyed hair colour.
Learning to ride a bike.
Body piercing.

11. POLLINATION
Reproduction in plants involves the pollen (male sex cell) fertilising the egg cell (female sex cell).
The pollen has to get from one flower to another and this is called pollination.
When the pollen lands on the top of the carpal it grows pollen tubes down towards the ovule. The egg cells become fertilised and the seeds are made.
Pollen on carpal
Pollen tube grows
fertilisation
Seeds are made

12. FERTILISATION Correct order: 3, 5, 6, 1, 2, & 4.
Put the following sentences into the correct order to explain fertilisation in plants.
The pollen tube reaches the egg cell.
The egg cell and the pollen fuse.
The pollen arrives at the stigma.
The seed that grows controls genes from both the pollen grain and the egg cell.
The pollen tube grows down the style from the pollen grain.
The pollen tube reaches the ovule, carrying the pollen nucleus.
Correct order: 3, 5, 6, 1, 2, & 4.

13. SPECIES Look at the flowers below. They are all called Fuchsia.
A species is a group of living things with similar features that can breed together to produce fertile offspring.
Within any species there is variation.
Look at the flowers below. They are all called Fuchsia.
What variation can you see between them?
These are different modern
Fuchsias.

14. SPECIES The differences are: Colour. Petal shape. Petal size.
Flower size.
Single coloured or double coloured.
This is the tiny original flower before specialists began to breed them.

15. DISCONTINUOUS or CONTINUOUS VARIATION?
Variation can be classed as:
Discontinuous:
All possibilities fit into neat classes, e.g. yes or no and can be shown on a bar chart or a pie chart.
Eye colour. Could be Blue or Brown or Green.
There are three choices so there are definite bars or sections on charts.

16. DISCONTINUOUS or CONTINUOUS VARIATION?
Variation can be classed as:
Continuous:
There are a range of possibilities whereby you usually have to measure things.
These can be shown on a line graph.
Length of hair could go from very short to long but could be any length in between!

17. VARIATION
Variation can be inherited or environmental and continuous or discontinuous.
Complete the table below to show the type of variation seen for each example.
Inherited.
Environmental.
Continuous.
Discontinuous.
Blood group.
Tongue Rolling.
Height.
Learning to ride a bike.
Having body piercing.
Hair colour.

18. Some variations are more desirable than others.
SELECTIVE BREEDING
Some variations are more desirable than others.
For example, cows that produce a high yield of milk are better for farmers than those that don’t produce a lot of milk.
Friesian (black and white cows) are very good at producing milk.
Charolet cattle are very good at producing top quality meat.
They are poor milk producers.

19. This is called selective breeding.
For this reason, farmers will select a cow to mate that produces a high yield of milk. The offspring should also produce a high yield of milk.
This is called selective breeding.
Selective breeding can also be used for plants. Bigger and brighter flowers will sell better than weaker flowers.
The stronger ones are used to produce the new seeds.

20. SELECTED BREEDS
We think of farming in Britain as something that happens in the countryside. The whole idea of farming is to get as much money from your crop or from your animals as possible.
Don’t forget animals are farmed for dairy products i.e. milk as well as meat.
This means we are able to support ourselves with food. Using machinery makes it easier.
In countries where machinery is not available the crops are very important and farmers will only use grain that will ‘grow well’. They have to use ‘breeds’ of animals and crops that can withstand extreme environmental factors.

21. SELECTED BREEDS
Goats are farmed in herds in high mountainous countries rather than sheep.
They can live on much poorer vegetation and on steeper slopes. The better goats give more milk for milk and cheese production.
Farmers will breed these for meat too.
What type of animals do you think the farmers in Peru keep?
Sheep.
There is still plenty of grass and the ground is quite flat. They have breeds that can stand the very cold conditions.

22. PLANT CLONES
In a plant called the bryophyllum the small buds on the edges of the leaves are ‘baby plants’. These drop off and can survive in the soil.
They are IDENTICAL TO THE PARENT plant. This is called ASEXUAL REPRODUCTION.
In the Strawberry plant the shoots called runners anchor to the ground. The new plant grows and the runner dies off. They are IDENTICAL TO THE PARENT plant.

23. PLANT CLONES
Plants like geraniums are also cloned by taking cuttings from their stems and rooting them in pots. This means that they will be identical to the parent plant.
The farmer can be sure that the plants will be identical to the parent and just as beautiful.
If a disease attacks that can kill this type of plant it will kill all of them as they are all EXACTLY THE SAME They are CLONES.

24. ANIMAL CLONES
This is DOLLY THE SHEEP with her mother.
Dolly only has a mother as there was no sperm used in her fertilisation.
Cells from her mother were implanted into a surrogate ewe who gave birth to Dolly.
Dolly is IDENTICAL TO HER MOTHER. She survived her birth and should have a normal life.
This is Dolly as she looks now.

25. PROBLEMS WITH CLONES
Dolly the sheep could be cloned in farming to produce lots of strong sheep that are the same and produce good lambs for meat.
What would happen if these sheep were attacked by a disease that was able to kill one of them?
They would all die!

26. SHOULD CLONING BE BANNED?
PROBLEMS WITH CLONES
Human cloning has been banned for religious and ethical reasons in many countries.
This is not to say that it has not been tried or even been successful.
SHOULD CLONING BE BANNED?

27. LET’S THINK
Put the following statements into the correct order, showing how selective breeding can be carried out with plants.
Cover the plant with a bag, then later collect the seeds and grow them.
Remove the anthers from the female plant and cover the flower with a bag.
The breeder selects two plants.
The other plant develops anthers as normal.
Collect the pollen and brush it onto the female plant.
Correct order: 3, 2, 4, 5, & 1.

28. LET’S THINK For each of the following statements
work out if it is True or False.
Human cells contain 46 chromosomes.
Selective breeding allows breeders to choose the best characteristics and produce offspring that have them.
Continuous variation means there is no range e.g. blood groups are identical.
An example of discontinuous variation is height.
An example of continuous, inherited variation is hair colour.
Variation means differences between organisms of the same species.
Chromosomes are found in the nucleus of a cell.
Chromosomes are made of DNA and this is our genetic material.
TRUE
TRUE
FALSE
FALSE
TRUE
TRUE
TRUE
TRUE

29. CHECK YOUR LEARNING! Where do we inherit our characteristics from?
Is variation within a species?
What are the names of the sex cells in animals and plants?
Does sexual or asexual reproduction take place in selective breeding?
Why would a farmer selectively breed wheat that gave a high crop yield?
Why are cows like Friesians selectively bred ?
In what way could a cloned human look different from the parent?

30. Check your learning- answers
We inherit our characteristics from our parents.
Variation within a species not between species.
The names of the sex cells in humans are SPERM (male) and EGGS/OVA (female). In plants these are POLLEN (male) and OVA/EGGS (female).
Selective breeding uses a male and a female parent.
It is sexual reproduction.
A farmer would make more money by being able to grow more wheat.
Friesian cows produce a lot of milk so they are selectively bred to do this.
A cloned human would only look different if the environmental factors changed this. Look at the model, she has changed her hair.
They could be triplets or clones!