AQA GCSE Biology Foundation (8461), Foundation tier · Inheritance, variation and evolution › Understanding of genetics and evolution
Practise Theory of evolution. 8 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
How Charles Darwin developed the theory of evolution by natural selection, why it was only gradually accepted, and how Lamarck's idea differed. This is in GCSE Biology only, not in Combined Science. Common questions ask why the theory was controversial or compare Darwin's and Lamarck's explanations.
Key facts
Darwin: observations on a round-the-world expedition + experimentation + discussion with other scientists
Darwin's theory: variation → the most suited are more likely to survive to breed → their characteristics are passed on
On the Origin of Species, published 1859
Slowly accepted: challenged the idea that God made all living things; insufficient evidence; mechanism of inheritance unknown for 50 years
Lamarck: changes during an organism's lifetime are inherited (in the vast majority of cases, this cannot happen)
Notes
Darwin's theory
Charles Darwin developed the theory of evolution by natural selection as a result of observations on a round-the-world expedition, backed by experimentation and discussion with other scientists.
Individual organisms within a species show a wide range of variation for a characteristic.
Individuals with characteristics most suited to the environment are more likely to survive to breed successfully.
The characteristics that have enabled these individuals to survive are then passed on to the next generation.
Darwin published his ideas in On the Origin of Species in 1859.
Why it was only gradually accepted
There was much controversy about these revolutionary new ideas, and the theory was only gradually accepted, for three reasons.
It challenged the idea that God made all the animals and plants that live on Earth.
There was insufficient evidence at the time the theory was published to convince many scientists.
The mechanism of inheritance and variation was not known until 50 years after the theory was published.
Lamarck's theory
diagram
Other theories, including that of Jean-Baptiste Lamarck, are based mainly on the idea that changes that occur in an organism during its lifetime can be inherited.
For example, Lamarck would have said that a giraffe that stretched its neck to reach high leaves would pass on a longer neck to its offspring.
We now know that in the vast majority of cases this type of inheritance cannot occur: changes to the body during life do not change the genes passed on in gametes.
The key difference: Darwin said variation already exists and the best-suited individuals survive and breed. Lamarck said organisms change during their lives and pass those changes on.
Darwin versus Lamarck, using giraffes' necks.
How to answer each type of question
Describe how Darwin developed his theory
2 marksGrade 4
Observations on a round-the-world expedition.
Experimentation and discussion with other scientists.
Example. Describe how Darwin developed his theory of evolution by natural selection. [2 marks]
Show the model answerHide the model answer
He made observations of living things on a round-the-world expedition (1). He backed up his ideas with experimentation and discussion with other scientists (1).
Don’t lose marks
Describing Lamarck's idea (e.g. 'the giraffe stretched its neck') when the question asks for Darwin's.
Saying Darwin knew about genes. The mechanism of inheritance was not known until about 50 years after he published.
Writing 'people didn't believe it' without saying why.
Getting the date wrong: On the Origin of Species was published in 1859.
More tips
Memory tricks
Three reasons for slow acceptance: God, gaps, genes (religion, not enough evidence, mechanism of inheritance unknown).
Lamarck = Lifetime changes (both start with L).
Darwin = variation first, then selection. Lamarck = change during life, then pass it on.
Exam technique
In Darwin v Lamarck questions, apply both theories to the organism in the question.
For 'why was it not accepted' questions, give separate reasons, not the same reason reworded.
Use 'changes during its lifetime' for Lamarck and 'variation' plus 'natural selection' for Darwin.
What each grade needs
What you need to be able to do, from the first marks up to the top grade.
Grade 3
Name the scientist behind natural selectionCharles Darwin developed the theory of evolution by natural selection.
Grade 4
Describe how Darwin developed his theoryObservations on a round-the-world expedition, backed by experimentation and discussion with other scientists.
Grade 5
Describe Darwin's theoryVariation exists; the individuals most suited to the environment are more likely to survive to breed and pass on their characteristics.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Complete the sentence. Individuals with characteristics most suited to the environment are more likely to ..................................... .
survive and breed (reproduce)
The statements describe how natural selection could change a population of rabbits living in a cold area. A Rabbits with thicker fur are more likely to survive the cold winters and breed. B Over many generations, most rabbits in the population have thick fur. C The rabbits in the population show variation in the thickness of their fur. D The alleles for thick fur are passed on to the offspring. Write the letters A, B, C and D in the correct order.
C, A, D, B
Darwin published his theory in 1859. Give the title of the book in which he published it.
On the Origin of Species
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy6 marks
Charles Darwin proposed the theory of evolution by natural selection.
(a) In which year did Darwin publish On the Origin of Species? Tick (✓) one box.[1]
1759
1859
1909
1959
(b) Which two of the following did Darwin use to develop his theory? Tick (✓) two boxes.[2]
Comparing the DNA of different species
Knowledge of geology and fossils
Observations made on a round-the-world expedition
Studying the structure of chromosomes
Testing bacteria for resistance to antibiotics
(c) Darwin’s theory was only gradually accepted. Give two reasons why.[2]
(d) Complete the sentence. Individuals with characteristics most suited to the environment are more likely to ..................................... .[1]
Show the answer and mark scheme
(a)Answer: 1859
(b)Answer: Knowledge of geology and fossils; Observations made on a round-the-world expedition
(c)
the theory challenged the idea that God made all the animals and plants that live on Earth
there was insufficient evidence at the time to convince many scientists
the mechanism of inheritance and variation was not known (until about 50 years later) / genes had not been discovered
(d)Answer: survive and breed (reproduce)
survive and breed / survive and reproduce
Question 2Medium7 marks
Some species of wading bird have very long legs. This lets them feed in deep water. Here are two statements that try to explain how the long legs evolved. Statement A: The ancestors of these birds stretched their legs to keep their feathers dry when wading into deep water. The legs of each bird became slightly longer during its life, and its offspring were born with these longer legs. Statement B: The ancestors of these birds had legs of different lengths. Birds with longer legs could reach more food, so they were more likely to survive and breed. Their offspring inherited long legs.
(a) Statement A is based on the theory of one scientist. Who was this scientist? Tick (✓) one box.[1]
Charles Darwin
Jean-Baptiste Lamarck
Gregor Mendel
Alfred Russel Wallace
(b) Scientists now know that the type of inheritance described in statement A does not happen in the vast majority of cases. Explain why.[2]
(c) Statement B does not explain how some birds came to have longer legs than others. Use your knowledge of genes to explain how a bird with longer legs could first have appeared in the population.[2]
(d) When Darwin published his theory, genes had not been discovered. Explain how the later discovery of genes helped scientists to accept Darwin’s theory.[2]
Show the answer and mark scheme
(a)Answer: Jean-Baptiste Lamarck
(b)
changes that happen to an organism during its lifetime do not (usually) change its genes / DNA
(so the change) is not passed on in the gametes / sex cells / only genes (alleles) are inherited
(c)
a mutation / change in the DNA (of a gene)
produced a new allele / new variant (that caused longer legs)
(d)
genes explained how characteristics are passed on / inherited by offspring
genes / mutations explained how variation arises (which Darwin could not explain)