4.6 Variation and Evolution Flashcards
What is a species?
- Organisms that have similar features.
- And can breed to produce fertile offspring.
What is meant by a characteristic?
A feature of an organism e.g. hair colour, eye colour etc.
What is meant by ‘variation’?
Differences in characteristics between organisms.
The two types of variation are…
- Genetic variation
2. Environmental variation
Genetic variation is caused by..
The different genes that are inherited from parents.
Give examples of characteristics that are controlled ONLY by genes,
Natural eye colour
Blood type
Genetic diseases
Gender
How are genes passed on from parents to offspring?
Through gametes (eggs and sperm).
Do identical twins show genetic variation? Why?
No - because they inherit the sae genes from their parents.
Environmental variation is caused by…
The conditions of the environment that the organism is in e.g. light intensity, food availability
True or False - Most characteristics e.g. skin colour, height etc. are due to genes AND the environment.
TRUE
How can a mutation lead to variation?
- DNA base sequences change.
- This leads to a change in the protein a gene codes for.
- This changes an organisms phenotype.
- This could alter characteristics slightly.
Do characteristics that are caused by only genes show continuous or discontinuous variation?
Discontinuous - because there are only a few specific characteristics e.g. blue, brown, green eyes.
Do characteristics that are caused by only the environment show continuous or discontinuous variation?
Continuous - because there is a whole range of possible values e.g. height can vary immensely.
Whose theory explains the process of evolution?
Charles Darwin
What did Darwin use to help him come up with his theory of how evolution happens?
- Observations from a round the world trip.
- Experimental data
- Discussions with other scientists.
- Knowledge about fossils and geology.
What did Darwin call his theory of how evolution happens?
The theory of ‘Natural Selection’.
The idea of the most well adapted organism outcompeting less well adapted organisms to survive and pass on their genes is sometimes called…
survival of the fittest.
Explain how the process of natural selection leads to an organism evolving.
RANDOM MUTATIONS lead to... VARIATION in a population. Some individuals have an ADVANTAGE... So will SURVIVE and REPRODUCE and.. Pass on GENES. Over time the population will have the advantageous characteristics.
How old is the Earth?
4.5 Billion years
How old is the Earth?
4.5 Billion years
What is the order of words that must be used when answering a 6 mark Q on how natural selection leads to evolution?
- Random Mutation (Red Monkeys)
- Variation (Violently)
- Advantage (Attack)
- Survive (Smelly)
- Reproduce (Red)
- Genes (Gorillas)
The characteristics that are expressed by an organism as a result of its genes are called its…
phenotype
What is meant by extinction?
When no individuals of a species remain alive.
List 5 causes of extinction.
- The environment changes too fast (habitat destroyed)
- A new predator kills them all.
- A new disease kills them all.
- They are out competed for food by a new species.
- A catastrophic event e.g. asteroid impact)
When did Darwin publish his book ‘On the Origin of Species’?
1859
Why was Darwin’s theory not immediately accepted by people?
- It went against religious believes.
- Darwin had no knowledge of genes or DNA because they had not been discovered.
- There was not much evidence.
Who else came up with a scientific hypothesis about evolution happens?
Jean-Baptiste Lamarck
Explain how Lamarck believed that evolution happens.
- An organism uses a characteristic a lot e.g. legs for running.
- The characteristic develops from being used e.g. legs get longer.
- The organisms offspring would acquire the changed characteristic.
What is a hypothesis?
A possible explanation to explain an observation e.g. Darwin and Lamarck both came up with different hypotheses to explain why organisms appeared to change over time.
Why might scientists develop different hypotheses to explain things that they observe?
- Different religious beliefs.
2. They are influenced by different people.
If a hypothesis has enough evidence to support it it becomes accepted and is called a…
theory e.g. the theory of evolution by natural selection
