DNA & Genetics — GCSE Biology Revision
Revise DNA & Genetics for GCSE Biology. Step-by-step explanation, worked examples, common mistakes and exam-style practice aligned to AQA, Edexcel, OCR, WJEC, Eduqas, CCEA, Cambridge International (CIE), SQA, IB, AP.
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Go to Chromosomes & GenesWhat is DNA & Genetics?
DNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. It is a double helix structure, made of two strands of nucleotides. A gene is a short section of DNA that codes for a specific protein.
Board notes: A fundamental topic for all major boards (AQA, Edexcel, OCR). The structure of DNA and the concept of the genome are key.
Step-by-step explanationWorked example
A short section of one DNA strand has the base sequence A-T-T-C-G. The complementary strand that pairs with it would have the sequence T-A-A-G-C. This complementary base pairing is fundamental to DNA's structure and replication.
Mini lesson for DNA & Genetics
1. Understand the core idea
DNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. It is a double helix structure, made of two strands of nucleotides.
Can you explain DNA & Genetics without copying the notes?
2. Turn it into marks
A short section of one DNA strand has the base sequence A-T-T-C-G. The complementary strand that pairs with it would have the sequence T-A-A-G-C.
Underline the method, evidence, or command-word move that would earn credit in GCSE Inheritance, Variation & Evolution.
3. Fix the likely mark leak
Watch for this mistake: Confusing DNA, genes, and chromosomes. DNA is the molecule itself. A gene is a segment of DNA that codes for a protein. A chromosome is a long, coiled structure made of DNA and proteins found in the nucleus.
Write one correction rule before doing another practice question.
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DNA & Genetics practice questions
These are original StudyVector questions for revision practice. They are not official exam-board questions.
Question 1
In one GCSE sentence, explain what DNA & Genetics is testing.
Answer: DNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. It is a double helix structure, made of two strands of nucleotides.
Mark focus: Precise definition and topic focus.
Question 2
A DNA & Genetics question uses an unfamiliar context. What should the answer do before adding detail?
Answer: It should name the process, variable, equation, particle model, or evidence being tested, then explain the result using precise scientific vocabulary.
Mark focus: Method selection and command-word control.
Question 3
A student makes this mistake: "Confusing DNA, genes, and chromosomes. DNA is the molecule itself. A gene is a segment of DNA that codes for a protein. A chromosome is a long, coiled structure made of DNA and proteins found in the nucleus." What should their next repair task be?
Answer: Do one DNA & Genetics question and review the mistake type.
Mark focus: Error correction and next-step practice.
DNA & Genetics flashcards
Core idea
What is the main idea in DNA & Genetics?
DNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. It is a double helix structure, made...
Common mistake
What mistake should you avoid in DNA & Genetics?
Confusing DNA, genes, and chromosomes. DNA is the molecule itself.
Practice
What is one useful practice task for DNA & Genetics?
Answer one DNA & Genetics question and review the mistake type.
Exam board
How should you use board notes for DNA & Genetics?
A fundamental topic for all major boards (AQA, Edexcel, OCR). The structure of DNA and the concept of the genome are key.
Common mistakes
- 1Confusing DNA, genes, and chromosomes. DNA is the molecule itself. A gene is a segment of DNA that codes for a protein. A chromosome is a long, coiled structure made of DNA and proteins found in the nucleus.
- 2Thinking that DNA is only in the nucleus. In eukaryotes, most DNA is in the nucleus, but mitochondria also contain their own small loop of DNA.
- 3Forgetting the four bases. The four nucleotide bases in DNA are Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Remember A always pairs with T, and C always pairs with G.
DNA & Genetics exam questions
Exam-style questions for DNA & Genetics with mark-scheme style solutions and timing practice. Aligned to AQA, Edexcel, OCR, WJEC, Eduqas, CCEA, Cambridge International (CIE), SQA, IB, AP specifications.
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Step-by-step method
Step-by-step explanation
4 steps · Worked method for DNA & Genetics
Core concept
DNA (deoxyribonucleic acid) is the molecule that carries the genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. It is a double heli…
Frequently asked questions
What is the structure of DNA?
DNA has a double helix structure, often described as a twisted ladder. The two sides of the ladder are made of alternating sugar and phosphate groups, and the rungs are made of pairs of nitrogenous bases (A with T, C with G).
What is the genome?
The genome is the entire set of genetic material in an organism. The Human Genome Project was a major international research effort to map the entire human genome.