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Year 9
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Which of these features are inherited, and which are acquired?
Characteristics unaffected by our environment
• Eye colour
• Natural hair colour
• Genetic disorders
• Blood group
Measure class• Height
• Index finger length
• Eye colour
• Hair colour
• 2nd toe longer than 1st toe?
• Attached or free ear lobe?
• Widows peak?
• Ability to roll tongue?
Blood groups of ethnic Chinese in Hong Kong
A B
AB
O
0
5
10
15
20
25
30
35
40
45
A B AB OBlood Group
Per
cent
age
of p
opu
latio
n
Source – HK Blood Transfusion Service 2005
Activity
1.Which of the features that we looked last week showed continuous variation?
2.Which features showed discontinuous variation?
Read the handout and answer the questions
To do…
• Read page ‘2.5 Heredity and variation’• Answer the questions in your booklet
height category / cm tally frequency
140 – 144
145 – 149
150 – 154
155 – 159
160 – 164
165 – 169
170 – 174
175 – 179
Investigating Continuous Variation• Place the heights of students in your class in the tally chart below.• Work out the frequency of each category.• Draw a histogram to display your results.
1 What is the modal (most common) height of people in your class?2 Height is an example of what sort of variation?3 What causes this sort of variation?
Key Question
1. What are chromosomes and genes?
A gene is a section of DNA which controls a certain feature
(eye colour, hair colour, etc).
1 Copy and complete.
Every cell has a nucleus inside of which are found our
___________ , made of a substance called ___*. Human body
cells each have ___ pairs of chromosomes, __ in total.
Chromosomes are in turn made from long strings of _____.
Each gene is a code for a single __________ , for example eye
colour. Every nucleus contains all of the _____ needed to make
a whole human, but not all are used in every _____.
2 Cut out the chromosomes on the worksheet and
arrange them into pairs which look the same. Stick
them onto your paper.
* deoxyribose nucleic acid
1 Copy and complete.
Every cell has a nucleus inside which are found our
chromosomes, made of a substance called DNA**. Human
body cells each have 23 pairs of chromosomes, 46 in total.
Chromosomes are in turn made from long strings of genes.
Each gene is a code for a single characteristic, for example
eye colour. Every nucleus contains all of the genes needed to
make a whole human, but not all are used in every cell.
2 Cut out the chromosomes on the worksheet and arrange them
into pairs which look the same. Stick them onto your paper.
* deoxyribose nucleic acid
Genes and alleles
Key Questions
1.How do we inherit features from our parents?
2.What are alleles?
3.What is a genetic cross?
Ovum (female gamete)contains 23 chromosomes
Sperm cell (male gamete)contains 23 chromosomes
blue eyes, bbrown eyes, B
(dominant) (recessive)
HeterozygousGenotype: BbPhenotype:
Brown eyes
blue eyes, bblue eyes, b
(recessive) (recessive)
HomozygousGenotype: bbPhenotype: blue
eyes
brown eyes, Bbrown eyes, B
(dominant) (dominant)
HomozygousGenotype: BBPhenotype:
Brown eyes
B = brown eyesb = blue eyes
Genotype Homozygous?Heterozygous?
Phenotype
BB
Bb
bb
B = brown eyesb = blue eyes
Genotype Homozygous?Heterozygous?
Phenotype
BB Homozygous Brown eyes
Bb Heterozygous Brown eyes
bb Homozygous Blue eyes
Genetic Crosses
Parents genotype:
Gametes genotype:
Genetic cross:
Bb x Bb
B b x B b
B bBb
Offspring phenotype:
Genetic Crosses
Parents genotype:
Gametes genotype:
Genetic cross:
Bb x Bb
B b x B b
B bB BB Bb
b Bb bb
Offspring phenotype: 75% brown eyes, 25% blue eyes
To do...
1. Read through ‘2.6 Chromosomes and Genes’Answer questions 1 – 5
2. Read through ‘2.7 More about chromosomes’Answer questions 1 – 3
Mutation
• A mutation is : a change in a gene or chromosome
• Mutations are;– Rare– Spontaneous– Random
• Mutation rate can be increased by mutagens;– Ionising radiation– Chemicals– Viruses
Ionising radiation
X - Rays
Radioactive Compounds
UV radiation
Chemicals
Alcohol
Pesticides
Tobacco Tar
Burnt fatty foods
Asbestos
Types of Mutation
1. Chromosome mutations– The number or structure of whole
chromosomes are altered• Down’s Syndrome
2. Gene Mutation– The code within the DNA of a gene is
altered. • Sickle Cell Anaemia
Down’s Syndrome
Down’s Syndrome
Sickle Cell Anaemia
Normal Haemoglobin
Sickle Haemoglobin
Mutation to the gene for haemoglobin
Sickle Cell Anaemia• Abnormal haemoglobin does not carry oxygen as
well as normal.
• Red blood cells become sickle shaped, and get stuck in capillaries.
• Individuals may:
Show poor growth.
Become tired easily.
Experience muscle or joint pain.
Be more prone to infections.
What pattern do you notice?
Video
http://www.nhs.uk/Conditions/Sickle-cell-anaemia/Pages/Symptoms.aspx
To do…
• Read ‘2.8 More about genes’• Complete the questions 1 – 4
• Prepare a poster or leaflet that outlines;– a particular type of mutation, – cause of the mutation– effects of the mutation
Discuss
• What is a the difference between aquired and inherited variation?
• What is the difference between a gene and an allele?
Natural Selection and Evolution
Darwin
Natural Selection
Darwin
Peppered Moth• Two phenotypes;
– Dark and Light (peppered)
• Live on tree trunks usually covered in lichen
• Are eaten by birds that use their sight to locate prey
In Normal Woodland
• In normal woodland the dark moths are very rare
• Why?
In Polluted Areas
• In polluted woodlands the light moths are very rare
• Why?
Why are their so many dark forms of the moth found in these areas?
Distribution in the UK 1958
Video…
ArtificialSelection
Artificial Selection
alleles
artificial
offspring
cattle
increase
fast growth
rates
decrease
humans
selective
repeated
docility
high milk yield
Humans select parents with desirable features for breeding. Some of the alleles for the desirable features are passed on to the offspring. Humans then select the offspring with the desirable features for further breeding. When this is repeated over many generations the alleles for features desired by humans will increase in the population, while the alleles for features not desired will decrease in the population. This is also known as selective breeding.
Artificial selection of wild cattle populations has lead to the development of modern cattle breeds. Characteristics desired by humans include docility, fast growth rates and high milk yield.
Genetic Engineering‘taking a gene from one species and putting it into
another’
Human Insulin
Insulin production
The gene for green fluorescent protein has been isolated from jelly fish, and…
GlofishTM
Herbicide resistant maizeGenes from a bacterium have been inserted into maize to
make it pest resistant (‘Bt Maize’)
Genes from a plant and a bacterium have been inserted into rice to increase its vitamin A content
(‘Golden Rice’)
To do
1. Go to the below page:http://www.pbs.org/wgbh/harvest/exist/
2. Read the information for and against GM food crops
3. Prepare an argument for or against genetically engineered food crops.
Food Chains
What do you know?
• Food Chain
Consumer
Herbivore Producer
Carnivore
Food Web
Photosynthesis
Habitat
What is a food chain?
grass
grasshopper
vole owl
All living organisms need ENERGY!
What is a food chain?
grass
grasshopper
vole owl
How is a food chain constructed?
grass
grasshopper
vole owl
producer consumer(herbivore)
Consumer (omnivore)
consumer (carnivore)
producer Primary
Consumer(herbivore)
Secondary Consumer(omnivore)
Tertiary Consumer(carnivore)
Food Webs
Pyramid of numbers
These pyramids are INVERTED
Pyramids of number do not take into account the mass of each individual
Pyramid of biomass
Pitfall trap
Pooter
quadrat
Random Sampling
• Random sample from each area as follows:
1. Choose a starting point in the area.
2. Use the table of random numbers to generate two
numbers.
3. Count the first number of paces forward, and the
second number of paces to the side.
4. Without looking, drop the quadrat over your
shoulder.
5. Return to the same starting point and repeat this
for at least three more quadrats
Random Sampling
quadrat
Random Sampling
• Random sample from each area as follows:
1. Choose a starting point in the area.
2. Use the table of random numbers to generate two numbers.
3. Count the first number of paces forward, and the second
number of paces to the side.
4. Without looking, drop the quadrat over your shoulder.
5. Return to the same starting point and repeat this for at least
three more quadrats
Quadrat Survey
Frogs =
Snakes =
Mongooses =
To do
1. Calculate the average number of snakes, frogs and mongooses per quadrat for Area A and Area B
2. Multiply up to find an estimate of the total number of each species for both Area A and Area B
3. Graph your results
Adaptations
• An adaptation is a feature that provides an advantage in the particular environment that an organism lives in.
• Adaptations evolve through years of natural selection.
• Adaptations can be physical or behavioural