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