lesson
Genes are sections of genetic material
1 · Learn
In cells with a nucleus, chromosomes contain long DNA molecules. A gene is a section of DNA involved in inherited characteristics, often through instructions affecting a protein. Different versions of a gene are called alleles.
Many characteristics involve several genes and environmental influences. A simple one-gene classroom model is useful for a particular pattern, not a complete explanation of every human difference.
2 · Worked example
A chromosome contains many genes. Calling a gene an entire chromosome confuses a section with the larger structure containing it.
3 · Your turn
How is a gene related to a chromosome in a cell with a nucleus?
Check your answer
A gene is a section of DNA carried on a chromosome; one chromosome contains many genes.
4 · Apply your learning
Make a labelled paper model and state that its scale and colour coding are representations, not microscopic observations.
Adult guidance and safety
Use supplied evidence and approved models. Practical science needs a qualified adult, appropriate equipment and a risk assessment. Do not attempt chemical reactions, heating, mains electricity or solar observation independently. Never request personal health or genetic disclosures.
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Check a calculation · Year 5 onward
Use this only when your teacher or adult allows a calculator for the task. Show your thinking first. It does not replace mental or written arithmetic and does not mark your lesson answer.
Powers, roots and trigonometry · Year 7 onward
Use only when the task allows a calculator. Choose one operation at a time and record your working. Trigonometry here always uses degrees (DEG), not radians. Inverse sine, cosine and tangent return an angle, not a reciprocal. Keep exact fractions and π in answers when requested.
Approximate numerical results use up to 12 significant digits. Inverse sine returns −90° to 90°, inverse cosine 0° to 180°, and inverse tangent −90° to 90°; these are principal values, not every possible solution of a trigonometric equation.
My observation notebook
Follow your teacher's approved method and safety instructions. Record the sample or supplied dataset, conditions, measurements with units and uncertainties where appropriate. Distinguish observations from explanations. A described experiment is not permission to carry it out; do not improvise equipment or invent missing results.
Ask your teacher for support with the method and recording. A prediction is what you think might happen; an observation is what you actually see, hear or feel safely.
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Interactive activity
Year 9 Science learning routine
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