biology 1b evolution and environment gcse core. gcse core meet our mr men and our little misses now...

Biology 1b Evolution and EnvironmentBiology 1b Evolution and EnvironmentGCSGCSEE

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Meet our Mr Men And our Little Misses

Now lets meet their children!

Characteristics

Starter: Characteristics from sexual reproduction leading to variation


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Starter: Characteristics from sexual reproduction leading to variation


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Objective

To investigate how sexual reproduction can lead to variation within a species.

Success Criteria

By the end of the lesson I:

• can identify the two types of reproduction as sexual and asexual reproduction.

• can explain the differences between sexual and asexual reproduction in that sexual reproduction leads to variation because the genes from two parents are mixed to create a new individual whereas in asexual reproduction there is only one parent and hence no mixing.

• can explain in detail how sexual reproduction leads to variation within a species using the correct scientific key words.


CORCOREE

chromosome from female parent

chromosome from male parent

In most cells chromosomes are matched in pairs based on their size and shape.

Where do chromosomes come from?

Each pair of chromosomes contains one chromosome that has been Each pair of chromosomes contains one chromosome that has been inherited from each parent.inherited from each parent.


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• Inside the NUCLEUS of every one of your cells there are CHROMOSOMES.

• CHROMOSOMES are coiled up DNA strands.

• On each CHROMOSOME there are several thousand GENES.

• GENES are shorter sections of DNA that code for particular CHARACTERISTICS

• GENES provide instructions to make PROTEINS that control the functions of the cell and therefore determining how the body functions (characteristics)

What’s in your genes?


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Asexual ReproductionAsexual reproduction only involves 1 parent and so Asexual reproduction only involves 1 parent and so gives rise to offspring known as gives rise to offspring known as CLONES. CLONES. Why?Why?

Daffodils can reproduce both Asexually and Daffodils can reproduce both Asexually and Sexually! Why would this make these plants more Sexually! Why would this make these plants more successful? Explain the differences between the successful? Explain the differences between the two types of offspring? two types of offspring?


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Sexual Reproduction• All living things can

reproduce.

• In most animals and plants this usually happens by sexual reproduction.

• This is when a male and a female mate, and produce offspring using sex cells.

• The young plants or animals will have similar characteristics to their parents but will not be identical to them.


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• Sexual reproduction involves special Sexual reproduction involves special sex cells called gametes.sex cells called gametes.

• Male animals produce gametes called Male animals produce gametes called sperm cells and female animals make sperm cells and female animals make gametes called egg cells.gametes called egg cells.


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Draw and label sex organs in plants

• In plants, the female sex cells In plants, the female sex cells are also called egg cells; the are also called egg cells; the male sex cells are found in male sex cells are found in pollen grains in the anthers.pollen grains in the anthers.


CORCOREE

What is the difference between Pollination and fertilisation

Pollination is ………………..Pollination is ………………..

Fertilisation is Fertilisation is …………………..…………………..


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Variation

Why is variation important ???

Increase genes in a population

Allow survival of the fittest

Whole population will not be wiped out


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THINK

If one parent has blue eyes and one parent has brown eyes what

colour eyes will their children have?

Can you prove this?

Sexual reproductionSexual reproduction is VERY risky as it relies on the is VERY risky as it relies on the joining of two sex cells. Even so, sexual joining of two sex cells. Even so, sexual reproduction is SO important for variation amongst reproduction is SO important for variation amongst species and hence survival that it can be seen in species and hence survival that it can be seen in almost all types of plants and animalsalmost all types of plants and animals


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• Each parent will have two chromosomes that contain the gene for eye colour.

Blue eyesBrown eyes

How can we represent the different eye colours?

Gene for eye colour

Each pair of genes affects a different characteristic

Each gene can have a different form. The versions of the same gene are called ALLELESALLELES


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• Different versions of the same gene are known as ALLELES.

• For example, blue and brown are two alleles for eye colour.

If we inherit one chromosome from each

parent what ALLELES will the offspring have?

I can explain how sexual reproduction leads to variation


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What colour eyes will the

offspring have?

Some alleles are DOMINANT over other forms of the gene.

What does this mean?

This means that the DOMINANT allele will always be expressed (shown) over the RECCESSIVE allele.

The Brown allele is

DOMINANT over the blue

allele.

All the offspring will have

Brown eyes



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B B

b

b

Punnett Squares

Alleles

Brown = B

Blue = b

Genotype

Homozygous Brown = BB

Homozygous Blue= bb

What does HOMOZYGOUS mean?



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Can two people with brown eyes have blue eyed children?

Genotype

Brown = Bb

Brown = Bb

Homozygous or

heterozygous?



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PHENOTYPE means the physical expression of the

gene.

i.e. what colour the eyes will be

GENOTYPE is the pair of alleles for a characteristic

i.e. BB or Bb or bb



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There are genes that decide whether;

• your earlobes are attached close to the side of your head or hang freely

• your thumb is straight or curved

• you have dimples when you smile

• you have hair on the second segment of your ring finger

You are going to complete an investigation on You are going to complete an investigation on babies lobes!babies lobes!

INVESTIGATION

ATTACHEDATTACHED

HANG FREELYHANG FREELY

STRAIGHTSTRAIGHTCURVEDCURVED


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Recap

How many chromosomes?

How many pairs?

Where are they found?

In most cells chromosomes are matched in pairs based on their size and shape.

PLENARY


CORCOREE

Objective

To investigate how sexual reproduction can lead to variation within a species.

Success Criteria

By the end of the lesson I:

• can identify the two types of reproduction as sexual and asexual reproduction.

• can explain the differences between sexual and asexual reproduction in that sexual reproduction leads to variation because the genes from two parents are mixed to create a new individual whereas in asexual reproduction there is only one parent and hence no mixing.

• can explain in detail how sexual reproduction leads to variation within a species using the correct scientific key words.

biology 1b evolution and environment gcse core. gcse core meet our mr men and our little misses now...

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