Biology Chapter on Cancer and Respiration

Cancer

• Tumours form when cells divide uncontrollably, being either benign (non-cancerous) or malignant (cancerous).
• Cancers are malignant tumours, and can be fatal.
• Various risk factors can increase the chance of developing certain cancers.

Growth of Tumours

• Healthy cells have controlled growth and division.
• Changes in DNA lead to uncontrolled cellular division, forming a tumour.
• Cell division by mitosis depends on genes controlling the exact number of cells needed.

Respiration

• Respiration is a vital process for all living organisms.
• Organisms respire aerobically when oxygen is present.
• Organisms respire anaerobically when oxygen is lacking.
• Respiration releases energy through the breakdown of glucose.
• Animals get glucose from the food they consume.
• Plants make glucose via photosynthesis.

Respiration Revision

• In all living things, respiration continuously releases energy.
• Respiration is an exothermic reaction (releases energy).
• Energy is needed to build molecules like proteins.
• It maintains body temperature to keep enzymes working.
• Two types of respiration are aerobic and anaerobic.

Aerobic Respiration

• When there's enough oxygen, cells use aerobic respiration.
• This converts glucose and oxygen into carbon dioxide, water, and energy.
• Aerobic respiration is the most efficient way to release energy.
• This process happens in the mitochondria.

Anaerobic Respiration

• When cells lack oxygen, anaerobic respiration occurs.
• In animals, glucose converts to lactic acid and releases energy.
• In plants and yeast, glucose converts to ethanol and carbon dioxide, releasing energy.
• This process is less efficient than aerobic respiration.

Fermentation

• Fermentation is a type of anaerobic respiration in yeast cells.
• It is important in alcoholic drinks and bread production.
• Ethanol is produced through this process, used in alcoholic beverages.
• Carbon dioxide is produced, causing dough to rise.

Metabolism

• Metabolism describes the chemical reactions in a cell or organism.
• Some reactions join smaller molecules to make bigger ones (e.g., glucose and nitrates to form proteins, glucose molecules make starch/cellulose/glycogen, fatty acids and glycerol form lipids).
• Other reactions break down large molecules into smaller ones (e.g., glucose is broken down in respiration, excess protein broken down into urea).
• Enzymes control all these reactions.

Plant Metabolism

• Plants do respiration and photosynthesis.
• Respiration releases energy from glucose.
• Photosynthesis uses light energy to produce glucose from carbon dioxide and water.
• Glucose can be stored as starch or cellulose.
• Glucose can also react with soil nitrates to make amino acids.

Animal Metabolism

• Animals consume food molecules and break them down.
• Starch breaks down into glucose.
• Proteins break down into amino acids.
• Lipids break down into fatty acids and glycerol.
• Glucose is used for respiration or stored as glycogen.
• Excess amino acids are converted to urea and excreted.

Photosynthesis

• Photosynthesis is how plants make their own food (glucose).
• This takes place in the chloroplasts.
• It requires light energy, carbon dioxide, and water.
• It produces glucose and oxygen.
• Many things affect the rate of photosynthesis (e.g. light intensity, temperature, carbon dioxide levels).

Exercise and Respiration

• During exercise, muscle cells need more energy.
• This means they need to respire more rapidly.
• To meet this demand, breathing, heart, and blood flow increase.
• If oxygen is insufficient, the muscles resort to anaerobic respiration, producing lactic acid.
• Lactic acid builds up causing fatigue and an oxygen debt.
• The body needs extra oxygen to remove the lactic acid, leading to a higher breathing rate and heart rate for a time after exercise.

This quiz covers key concepts related to cancer and cellular respiration. It explores tumour formation, the differences between benign and malignant tumours, and the processes of aerobic and anaerobic respiration. Assess your understanding of these vital biological processes.