Natural selection 5.2

Natural selection increases the frequency of successful adaptations in a species and it relies on variation in the features of the species as well as overproduction of offspring, a struggle for survival and survival of the fittest. It is the driving force of evolution and this topic looks at all aspects of the process.

Key concepts

Learn and test your biological vocabulary for 5.2 Natural selection using these Natural Selection revision flashcards.

Essentials

These slides summarise the essential understanding and skills in this topic. 
They contain short explanations in text and images - good revision for all students.

Read the slides and look up any words or details you find difficult to understand.

Summary

Summary list for topic 5.2 Natural selection

  • Natural selection requires;
    • variation in adaptations within a species.
    • overproduction of offspring.
    • best adapted individuals have better survival rates.
    • so they reproduce more and pass on successful adaptations to offspring.
  • Variation within a species can be caused by Mutation, meiosis and sexual reproduction.
  • Adaptations are advantageous characteristics of an individual for it's way of life.
  • More offspring are produced by the best adapted individuals while less well adapted individuals die or produce fewer offspring.
  • Adaptations / characteristics are passed on to offspring (inheritance).
  • Natural selection increases the frequency of the better adaptations and decreases the frequency of other characteristics. This leads to changes in characteristics within the species.

Skills (can you ....)

  • Analyse data about the changes in beak lengths of finches on Daphne Major.
  • Understand how the evolution of antibiotic resistance in bacteria occurs by natural selection.

Mindmaps

These diagram summaries cover the main sections of topic 5.2 Natural selection.
Study them and draw your own list or concept map, from memory if you can.

Exam style questions

Exam style question about evolution by natural selection

Explaining the process of evolution by natural selection is an important skill from this topic.

Answer the question below, on a piece of paper, then check your answer against the model answer below.

Describe how natural selection can lead to antibiotic resistance in bacteria. [4]

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

Click the + icon to see a model answer.

Extra exam question about causes of variation   - - -  click the + symbol to open it -- >

Exam style question about causes of variation in evolution

This question requires knowledge of the causes of variation

Question: Describe three causes of variation within a species. (6 marks)

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

....................................................................................... ............................................................................

Click the + icon to see a model answer.

Test yourself

Multiple choice questions

This is a self marking quiz containing questions covering the topic outlined above.
Try the questions to check your understanding.


START QUIZ!

 Drag and drop activities

Test your ability to construct biological explanations using the drag and drop questions below.

Natural selection is a driving force in evolution.

Drag and drop the correct word or phrase into the gaps to summarise natural selection.

1

resources designed chance more natural selection survival of the fittest adapted genes genome inherited characteristics survive to breed evolution generations not competition

When organisms reproduce, they invariably produce offspring than the environment can support. This creates for and a struggle for survival.

The organisms best to compete for resources, mates (“fittest”) organisms survive, this is natural selection by .

The organisms with adaptations best suited to the environment and pass on their to subsequent . Genes that are advantageous will gradually be lost from the population over generations.

This gradually alters the of the population.

The gradual change in the of the population is evolution: the species has evolved by .

Evolution is the gradual change in the genome of the population as genes with survival value prevail.


Just for fun

Everyone needs a bit of fun while they revise. Try this Natural selection terms card matching game

Can you reach the leader board?

MY PROGRESS

How much of Natural selection 5.2 have you understood?