MAKING SENSE OF RESPIRATION IGCSE Biology 1 1

MAKING SENSE OF RESPIRATION IGCSE Biology 1. 1 Life Processes – Respiration Brought to you by Mr. Exham. com Image © Depositphotos. com/[julos #4371007]

Learning Objectives • Can you remember how respiration releases energy? • Can you write out the word equation, and the balanced symbol equation, for aerobic respiration? • Can you write out the word equation for anaerobic respiration? • What are the differences between aerobic and anaerobic respiration? • Can you describe simple experiments to show that carbon dioxide and heat are produced by respiring seeds or other suitable living organisms?

Respiration • A chemical reaction that happens in all our cells to release energy. • This can be used for 1. Contraction of muscle cells, producing movement 2. Active transport of molecules and ions 3. Building large molecules, such as proteins 4. Cell division • The reaction also releases some heat which is used to maintain steady body temperature.

Aerobic Respiration Glucose + Oxygen Carbon Dioxide + Water + Energy

Aerobic Respiration Word equation: Glucose + Oxygen Chemical equation: C 6 H 12 O 6 + 6 O 2 Carbon Dioxide + Water + Energy 6 CO 2 + 6 H 20 + Energy

Aerobic Respiration Glucose + Oxygen C 6 H 12 O 6 + 6 O 2 Carbon Dioxide + Water + Energy 6 CO 2 + 6 H 20 + Energy • Respiration using oxygen. • Occurs in the mitochondria of a cell.

Anaerobic Respiration • Respiration without oxygen. • We shall look at examples in two types of cell.

Anaerobic Respiration • Respiration without oxygen. YEAST

Anaerobic Respiration • Respiration without oxygen. YEAST MUSCLE

Anaerobic respiration in yeast cells • Also known as. • Yeast cells are single celled fungi. • Used for commercial purposes such as brewing.

Anaerobic respiration in yeast cells • Also known as. • Yeast cells are single celled fungi. • Used for commercial purposes such as brewing. Glucose Ethanol + Carbon Dioxide (+ some energy)

Anaerobic respiration in muscle cells • Occurs when the blood cannot reach the muscles fast enough to supply them with the required oxygen. http: //www. flickr. com/photos/sumofmarc/7715537014/

Anaerobic respiration in muscle cells • Occurs when the blood cannot reach the muscles fast enough to supply them with the required oxygen. Glucose Lactic Acid (+ some energy) http: //www. flickr. com/photos/sumofmarc/7715537014/

Oxygen Debt • Anaerobic respiration provides enough energy to keep the muscles working for a short time. • However lactic acid builds up in the blood which causes cramps. • The lactic acid has to be broken down using oxygen. • The volume of oxygen needed to completely oxidise the lactic acid that builds up in the body during anaerobic respiration is called

Aerobic or anaerobic Anaerobic Uses oxygen No oxygen Occurs in mitochondria of cell Occurs in cytoplasm of cell Releases lots of energy Releases only a small amount of energy Carbon dioxide and water is produced Lactic acid or ethanol is produced

Respiration experiments • This apparatus can be used to investigate how small living organisms respire such as woodlice, maggots or germinating seeds. Living organisms Gauze Hydrogencarbonate indicator – This will change colour from red to yellow when the carbon dioxide level increases due to respiration.

Respiration experiments The germinating seeds are respiring and therefore releasing heat. The boiled seeds have been killed and are therefore not respiring anymore. Cotton wool Thermometer Thermal flask Germinating seeds Boiled seeds