Biology (Respiration)

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RESPIRATION
Syllabus
* Define respiration
* State the uses of energy in the body of humans
* Define aerobic respiration
* State the equation for aerobic respiration using symbols * Define anaerobic respiration
* State the word equation for anaerobic respiration in muscles during hard exercise * State the balanced equation for anaerobic respiration in muscles (C6H12O6 → 2C3H6O3) and the microorganism yeast (C6H12O6 →2C2H5OH + 2CO2), using symbols * Describe the effect of lactic acid in muscles during exercise * Describe the role of anaerobic respiration in yeast during brewing and bread-making * Compare aerobic respiration and anaerobic respiration in terms of relative amounts of energy released * List the features of gas exchange surfaces in animals

* Identify on diagrams and name the larynx, trachea, bronchi, bronchioles, alveoli and associated capillaries * Describe the role of the ribs, the internal and external intercostal muscles and the diaphragm in breathing * State the differences in composition between inspired and expired air * Use lime water as a test for carbon dioxide to investigate the differences in composition between inspired and expired air * Explain the role of mucus and cilia in protecting the gas exchange system from pathogens and particles * Investigate and describe the effects of physical activity on rate and depth of breathing

* Explain the link between physical activity and rate and depth of breathing in terms of changes in the rate at which tissues respire and therefore of carbon dioxide concentration and pH in tissues and in the blood

Respiration: It is the chemical reactions that break down nutrient molecules in living cells to release energy.

Use of energy in the body of humans: In humans, our body use energy, released by respiration, for the following processes: * Muscle contraction
* Cell division
* Absorption of nutrients in the gut by active transport
* Sending impulses along nerves
* Protein synthesis for making enzymes, some hormones and antibodies * Making new cell membranes and cell structures like the nucleus during growth * Producing heat inside the body to keep the body temperature constant

All of this energy comes from the food we eat. The main nutrient used to provide energy in cells is glucose as it contains a lot of chemical energy.

Types of respiration: Organisms respire by two ways-aerobic and anaerobic respirations.

Aerobic respiration: the release of a relatively large amount of energy in cells by the breakdown of food substances in the presence of oxygen.

Word equation for aerobic respiration:

Glucose + oxygen carbon dioxide + water

Equation for aerobic respiration using symbols:

C6H12O6 + O2 6CO2 + 6H2O

[Experiment: investigating heat production by germinating seeds. Fish book-page 113]

[Experiment: comparing energy content of two kinds of food. Fish book-page 114]

--------------------------------------------------------------------------------------------------------------------- Anaerobic respiration: the release of a relatively small amount of energy by the breakdown of food substances in the absence of oxygen.

Examples for anaerobic respiration:
* Yeast, a single celled fungus, can respire anaerobically when oxygen is absent or in short supply in their surroundings. It breaks down glucose to make alcohol and carbon dioxide.

Word equation for anaerobic respiration in yeast:

Glucose alcohol + carbon dioxide

Balanced equation:

C6H12O6 2C2H5OH + 2CO2

* In mammals, muscle cells respire anaerobically during hard exercise for a short time, as not enough...
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