A disease in which changes in cells make them grow and divide uncontrollably to form a mass of abnormal cells.

A lump of cells formed when cells divide uncontrollably instead of stopping when they should.

Describe the difference between a benign and a malignant tumour.

A benign tumour stays in one place within a membrane and does not invade other tissue, while a malignant tumour grows into surrounding tissue and its cells can break away.

What are secondary tumours and how do they form?

New tumours that form when cells break off a malignant tumour, travel in the blood or lymph and start dividing in another part of the body.

Explain why a benign tumour can still be dangerous.

As it grows it can press on nearby organs or blood vessels, which is serious in a confined space such as inside the skull.

OCR GCSE Biology A J247

Cell Level Systems

Topic overview Microscopy, and sub-cellular structures DNA structure: polymer, double helix and nucleotides Enzyme action, and investigating enzymes Cellular respiration as an exothermic process Aerobic and anaerobic respiration compared Synthesis and breakdown of carbohydrates, proteins and lipids Photosynthesis: producers and the process Photosynthesis as endothermic, and investigating it Limiting factors in photosynthesis

Community Level Systems

Topic overview Cycling materials, and the role of microorganisms The carbon and water cycles, and decomposition Levels of organisation, and abiotic and biotic factors Interdependence, competition and trophic levels Pyramids of biomass and the efficiency of transfer

Genes, Inheritance and Selection

Topic overview Genetic terms, and the genome Genome, environment and mutations Asexual and sexual reproduction compared Haploid, diploid and meiosis Single gene inheritance and Punnett squares Sex determination, multiple genes and Mendel's work Variation within a population, and classification Natural selection and evolution Evidence for evolution, and the work of Darwin and Wallace

Global Challenges

Topic overview Field investigations, and human impact on ecosystems Maintaining biodiversity, monitoring conservation and ecotourism Food security, agricultural and biotechnological solutions Selective breeding and genetic engineering Health, disease, and types of disease Interactions between diseases, and how they spread Reducing the spread of disease, and named examples Physical and chemical plant defences White blood cells, antibodies and platelets Non-specific defences and the immune system Vaccines, medicines and aseptic technique Developing new medicines, and non-communicable disease Treating cardiovascular disease, and lifestyle factors Cancer, and the use of stem cells in medicine Gene technology in medicine, and the human genome

Organism Level Systems

Topic overview The nervous system and coordinated responses The reflex arc The eye and its common defects The structure and function of the brain Hormones and the endocrine glands Hormones in reproduction and the menstrual cycle Methods of contraception Tropisms, auxin and the roles of plant hormones Homeostasis, and the skin in temperature control Insulin and the control of blood glucose Type 1 and type 2 diabetes Osmotic changes in body fluids, and the kidneys Kidney structure and the parts of the tubule

Scaling Up

Topic overview Diffusion, osmosis and active transport Mitosis, the cell cycle and cell differentiation Stem cells in animals and meristems in plants Surface area to volume ratio and exchange surfaces The circulatory system, the heart and blood vessels Red blood cells and plasma Root hair cells, transpiration and translocation Xylem and phloem Factors affecting water uptake, and the potometer

Global Challenges

Cancer, and the use of stem cells in medicine

3 things to know
Paper 2

Overview

What cancer and tumours are, why changes in genes cause uncontrolled division, benign and malignant tumours and how secondary tumours form, risk factors and why early detection helps, the benefits and risks of stem cell treatments, bone marrow transplants, embryonic stem cells and the ethical objections to them, therapeutic cloning, and why transplants are rejected and how rejection is reduced.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

What is cancer?

Key term

What is a tumour?

Key term

Explain why changes in a cell's genes can lead to cancer.

Questions from this subtopic

Each one with the model answer underneath.

1
What is cancer?
Model answer
A disease in which changes in cells make them grow and divide uncontrollably to form a mass of abnormal cells.
2
What is a tumour?
Model answer
A lump of cells formed when cells divide uncontrollably instead of stopping when they should.
3
Explain why changes in a cell's genes can lead to cancer.
Model answer
The genes that control the cell cycle are altered, so the signals that normally stop the cell dividing no longer work.
4
Describe the difference between a benign and a malignant tumour.
Model answer
A benign tumour stays in one place within a membrane and does not invade other tissue, while a malignant tumour grows into surrounding tissue and its cells can break away.
5
What are secondary tumours and how do they form?
Model answer
New tumours that form when cells break off a malignant tumour, travel in the blood or lymph and start dividing in another part of the body.
6
Explain why a benign tumour can still be dangerous.
Model answer
As it grows it can press on nearby organs or blood vessels, which is serious in a confined space such as inside the skull.

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Cell Level Systems

Community Level Systems

Genes, Inheritance and Selection

Global Challenges

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Algae and .

phytoplanktonfungianimals

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AA diet high in sugar and fat leads to obesity.

BBody cells then respond poorly to insulin.

CBlood glucose concentration cannot be controlled.

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Egestion means passing out of undigested food as faeces.

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