Topic 4

Define: Evolution

Gradual change in a species over time.

Which scientist believed evolution occurs by natural selection?

Charles Darwin

What is natural selection?

Organisms within a species with certain characteristics are more likely to survive than others as they are better suited to their environment. This means that they have the beneficial allele.

Which mnemonic do we use to answer a question about natural selection?

G enetic variation

E nviromental change

N atural selection

I nheritance

E volution

Why did many people doubt Charles Darwin’s theories?

• It challenged the belief that God created all living things.

• Little evidence - not many fossils + no knowledge of antibiotic resistance.

• Little understanding of genes, inheritance etc.

What is classification?

Organising living things into groups according to similar characteristics.

Name the 7 groups to classify animals into from largest to smallest

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

Name the 7 groups to classify animals into from smallest to largest

• Species

• Genus

• Family

• Order

• Class

• Phylum

• Kingdom

Define: Species

A group of similar organisms that can breed to produce fertile offspring.

Name the 5 kingdoms organisms can be organised into

• Animal

• Plant

• Fungi

• Bacteria/Prokaryotes

• Protist

Name the 3 domains organisms can be organised into

• Archaea

• Bacteria

• Eukaryotes/Eukaryota

Is the domain or kingdom system more accurate? Why?

Domains because it uses genetic analysis to show the similarities and relationships between animals.

Describe organisms in the animal kingdom

• Multicellular

• Nuclei

• No cell wall

• Eat other organisms

Describe organisms in the plant kingdom

• Multicellular

• Nuclei

• Cellulose cell wall

• Makes food via photosynthesis

Describe organisms in the fungi kingdom

• Mainly multicellular. Some, such as yeast are unicellular.

• Chitin cell wall

• Nuclei

• Digest dead materials

Describe organisms in the bacteria kingdom

• Unicellular

• No nucleus

• Cell wall

Describe organisms in the protist kingdom

• Mainly unicellular, some multicellular.

• Some have cell walls.

Which domain contains ancient bacteria?

Archaea

Which domain contains true bacteria?

Bacteria

Which domain contains animals, plants, fungi and protists?

Eukaryotes/Eukaryota

Who is the oldest human fossil and when were they discovered?

Ardi - 4.4 million years ago

How was Ardi similar to humans?

Walked upright

How was Ardi similar to apes?

• Long arms and legs

• More body hair

• Shorter

• Smaller head

• Big toes

Describe the fossil of Ardi

• Walks up right

• Long arms and legs

• More body hair

• Shorter

• Smaller head

• Big toes

When was Lucy discovered?

3.2 million years ago

Describe the fossil of Lucy

• Walks more upright than Ardi.

• More human like feet - smaller, arched.

• Small head still but slightly bigger than Ardi.

Order the human fossils from oldest to newest

• Ardi

• Lucy

• Homo habilis

• Homo erectus

• Homo sapiens

What are the common evolution trends?

• Decease in body hair.

• Decrease in limb size/proportion.

• Increase in height.

• Increase in skull volume.

Are rock layers containing older rocks found closer or further away from the Earths surface?

Further away

Are rock layers containing newer rocks found closer or further away from the Earths surface?

Closer

Will more complex tools be found in older or newer rock?

Newer

What type of tools are found in newer rock?

Complex, sophisticated, sharp, specialised tools.

Will more simple tools be found in older or newer rock?

Older

What type of tools are found in older rock?

Simple, blunt tools.

If a fossil is found in a 200,000 year old rock, how old is the fossil?

200,000 - always the same age

What is a pentadactyl limb?

A limb with 5 units.

How does many species having a pentadactyl limb prove evolution?

• Despite looking externally different; this similarity shows that they all evolve from the same species or have a common ancestor.

Explain how bacteria can become resistant to antibiotics

• Bacteria have a high, medium or low resistance to antibiotics.

• Antibiotics are introduced to an environment.

• Antibiotics will first kill low resistance then medium resistance but if a person doesn’t continue to take antibiotics/doesn’t finish the course, high resistance bacteria remains.

• High resistant bacteria will breed and divide, passing on their beneficial allele to the offspring.

• Now antibiotics don’t work as all bacteria is highly resistant to it.

How can we reduce antibiotic resistance?

• Patients should always take full course every time.

• Reduce use of antibiotics in farm animals.

• Reduce the prescription of antibiotics for viral infractions.

Explain how humans can selectively breed plants/animals

1. Select partners with desired characteristic.

2. Breed organisms together.

3. Select offspring with desired characteristics.

4. Breed offspring together.

5. Repeat over many generations until all offspring have desired characteristics.

What are the advantages of selective breeding?

• Provides higher yields of crops.

• Leads to more profit; more wool, milk, meat produced.

• Creates a higher resistance to disease.

• Can be used for medical research.

What are the disadvantages of selective breeding?

• Can cause random genetic mutations.

• Inbreeding can cause health problems.

• No variation/Decrease in gene pool - more likely to suffer from environment changes or exposure to new diseases. Less chance of resistant alleles.

Define: Clone

A genetically identical copy.

What is tissue culture?

Cells grown on or in an artificial medium.

Why is tissue culture used in plants?

To preserve rare plants.

Explain how to clone plants using tissue culture

• Take a cutting of the parent plant/Remove tissue.

• Place cutting/tissue into growth medium (contains nutrients + growth hormones) under aseptic conditions.

• Wait until roots and shoots form.

• Put into soil.

What is added to the growth medium to help plants/animals to grow?

Nutrients + Growth Hormones.

Why are hormones and nutrients added to the growth medium?

To stimulate the growth of shoots and roots.

Why do we sterilise everything during tissue culture?

To kill pathogens and microbes that could harm the plant or be cloned on to the new plant.

Why is tissue culture used in animals?

Medical research.

Explain how to clone animals using tissue culture

• Take sample of tissue.

• Separate individual cells from tissue using enzymes.

• Place cells into a culture vessel and bathe in a growth medium.

• Cells begins to split via osmosis.

• Then, split cells into different vessels to encourage more growth and division for larger samples.

State three advantages of using a tissue culture or plant cuttings

• Preserves rare plants.

• Plants and animals can be used in medical research.

• Plant cuttings can produce clones quickest and cheapest.

Define: Genetic Engineering

Transfer of DNA from one organism to another, giving it desirable characteristics.

Which enzyme is used to cut the target gene out of the chromosome?

Restriction Enzyme

What are sticky ends?

Unpaired DNA bases.

Describe how to genetically engineer DNA

• Identify target gene then using restriction enzymes cut the target genes DNA cut out of the chromosome.

• This exposes the sticky ends of the target gene, which are unpaired DNA bases.

• The vector DNA is cut out using the same restriction enzyme and exposing its sticky ends.

• Ligase then complementary base pairs sticky ends of DNA and Target gene via weak hydrogen bonds.

• Put vector back into another cell. This will contain the target gene and therefore the cell can express it.

• Now the cell with the recombinant DNA/gene replicates and divides very quickly.

What are the benefits of genetic engineering?

• Faster than selective breeding to produce desired characteristics in an organism.

• Bt toxin can be inserted from bacteria to reduce need for pesticides.

• Herbicide resistant crops reduce the need for herbicides.

• Crops can have additional nutrients added.

• Disease or drought resistant crops allow for more crops to be produced, leading to healthier food and profit.

What are the risks of genetic engineering?

• Expensive and not all farmers can do. Some developing countries are therefore unable to do it.

• New genes found in food crops could cause allergic reactions to humans.

• Not ethical to interfere with nature.

• No long term studies on the effects.

• Genes could spread to wild populations e.g. the herbicide resistant gene could be picked up by weeds, creating a super weed.

How can Bt toxin be used to control pests?

• Genetic Engineering.

• Bt is removed from bacteria and inserted into the plants genome so it can produce the Bt toxin.

• This kills many of the insect larvae that are harmful to crops.

How can the Bt toxin become ineffective?

Insects such as aphids have become resistant to the toxin, so farmers still have to use pesticides. This could happen to other insects too.

What can a vitamin A deficiency cause?

Blindness

How can genetic engineering help to prevent blindness?

• People with a vitamin A deficiency cause blindness.

• Beta Carotene can be removed from wheat/carrots and insterted into golden rice.

• When eastern, the gene forms into vitamin A, preventing blindness.

Name 3 ways to increase crop yield

• Add Fertiliser

• Add Pesticides

• Use Biological Control

What does fertiliser add to the soil to help a plant grow?

Nutrients such as nitrates/phosphate.

How does adding fertiliser to the soil increase crop yield?

Adds minerals such as nitrates/phosphate that help the plant to produce proteins and DNA, promoting plant growth.

How does adding pesticides to the soil increase crop yield?

Pesticides are chemicals sprayed onto the plants by killing pests and therefore reducing the number of pests that eat crops.

What is biological control?

Using other organisms to control pests. This includes introducing a non native species to a population.

What is an example of biological control?

Cane toads were introduced to Australia to kill Beatles that were destroying crops.

What is a disadvantage of using fertiliser?

Eutrophication; damaged aquatic life.

What is a disadvantage of using pesticides?

Can harm humans if fruit is not washed before eating.

Give 3 disadvantages of using biological control

• Control organisms may kill other insects, impacting food chains/webs and unbalancing the ecosystem.

• Cane toads are now a pest in Australia because they poison the native species that eat them.

• The biological control organism must remain in the same place as the pests but organism may naturally move or reproduce and spread.