Year 11 - Science
Variation and genetic mutations
Variation and natural selection at the genetic level
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
This unit covers genetic variation, comparing asexual and sexual reproduction. It explores mutations' impact on phenotypes, evolution through natural selection, and how scientific theories develop, explaining how advantageous traits lead to adaptation.
Lesson Summary
You will learn to describe how mutations change the DNA sequence in the genome causing genetic variation, which can cause heritable variation in phenotype.
Key Notes
- Some variation in phenotype is caused only by the environment and is not heritable.
- Some variation is caused by genetic material; this can be passed on to offspring via gametes or asexual reproduction.
- A change in the sequence of bases in an organism's DNA is called a mutation and creates a genetic variant.
- Mutations happen at random (caused by carcinogens, or by ionising radiation, or by errors when DNA is copied).
- Most mutations have no effect on phenotype, some influence phenotype, and a few determine phenotype.
Vocabulary To Learn
- phenotype: The observable traits of an organism.
- variation: Differences between members of the same species.
- DNA: A large chemical molecule made of nucleotides. It carries the genetic code of all living organisms.
- mutation: A change in the nucleotide base sequence in the DNA of the genome.
- genetic variant: A region of DNA in which the sequence of nucleotide bases has been changed.
Common Mistakes To Avoid
- Students have many misconceptions about DNA including, for example, that DNA is alive.
3 Quick Questions (With Answers)
1. Explain the scientific idea in this lesson using two key points.
Some variation in phenotype is caused only by the environment and is not heritable. Some variation is caused by genetic material; this can be passed on to offspring via gametes or asexual reproduction.
2. Define this scientific word and use it in context. 'phenotype'
The observable traits of an organism. Include the word in a full scientific explanation, not as a single label.
3. Correct this common scientific misunderstanding.
Mistake: Students have many misconceptions about DNA including, for example, that DNA is alive. Correction: This lesson includes dual coded diagrams of DNA to help avoid embedding misconceptions.
More Lessons In This Unit
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