Biology Year 12 - Module 8 - Lesson 17

Genetic Disorders

Use this worksheet after reading the lesson to practise the key ideas and prove you can meet the success criteria.

Name

Date

Class

1. Key Ideas

When errors in DNA sequence or chromosome number cause non-infectious disease — from conception onwards

Types of genetic disorders: chromosomal abnormalities and single-gene (Mendelian) disorders
How non-disjunction produces chromosomal abnormalities

2. Success Criteria

By the end, you should be able to:

Types of genetic disorders: chromosomal abnormalities and single-gene (Mendelian) disorders
Examples: Down syndrome, Turner, Klinefelter, CF, PKU, Huntington's, haemophilia
Diagnostic tools: karyotyping, NIPT, amniocentesis, newborn screening

3. Key Terms

Genetic disorderA disease caused by an abnormality in an individual's DNA, either in chromosome number/structure or in a single gene sequence.

Chromosomal abnormalityDisorder caused by the wrong number or structural rearrangement of chromosomes (e.g. trisomy, monosomy, translocation).

Non-disjunctionFailure of homologous chromosomes or sister chromatids to separate during meiosis, producing gametes with extra or missing chromosomes.

Single-gene disorderDisease caused by a mutation in one specific gene; follows Mendelian inheritance patterns (autosomal recessive/dominant, X-linked).

PenetranceThe proportion of individuals with a given genotype who actually show the associated phenotype. A gene with 80% penetrance means 20% of carriers will not develop the condition despite having the genotype.

CarrierAn individual who carries one copy of a recessive disease allele but does not show symptoms. Two carriers have a 25% chance of producing an affected child.

4. Activity: Build the Lesson Map

Use the lesson to complete the table. Keep answers brief but specific.

Prompt	Your answer
Main concept
Important example
Common mistake to avoid
How this links to the next lesson

5. Short Answer Questions

1. Explain this lesson goal in your own words: "Types of genetic disorders: chromosomal abnormalities and single-gene (Mendelian) disorders". Use one specific example from the lesson.

Band 32 marks

2. Apply this idea to a new example: "Examples: Down syndrome, Turner, Klinefelter, CF, PKU, Huntington's, haemophilia". Show your reasoning clearly.

Band 43 marks

3. Analyse why this idea matters for understanding Genetic Disorders: "Diagnostic tools: karyotyping, NIPT, amniocentesis, newborn screening".

Band 54 marks

6. Extend: Apply the Idea

Band 5/65 marks

A student gives a memorised answer about Genetic Disorders but does not use evidence or reasoning.

Improve the answer by writing a stronger response that uses accurate terminology, a relevant example and a clear explanation.

7. Multiple Choice

1. What is the best first step when answering a question about Genetic Disorders?

A. Identify the key concept being tested

B. Write every fact from memory

C. Ignore the command word

D. Skip examples and evidence

2. Which answer would show stronger understanding of Genetic Disorders?

A. An answer with accurate terms and reasoning

B. A copied definition only

C. A single-word response

D. An answer with no example

3. What should you do if a question asks you to explain?

A. Link the idea to a reason or cause

B. List unrelated facts

C. Only draw a diagram

D. Write the shortest possible answer

8. Success Criteria Proof

Finish with evidence that you can do each success criterion.

Success criterion 1

Prove that you can: Types of genetic disorders: chromosomal abnormalities and single-gene (Mendelian) disorders