Biology: B4.2: Respiration

Aerobic respiration is summarised by the equations:

(1) Glucose + oxygen = carbon dioxide + water (+ energy). (2) C6H12O6 + 6O2 = 6CO2 + 6H2O (+ energy).

During aerobic respiration chemical reactions occur that use _______(1) and ______(2) and release ______(3).

(1) Glucose. (2) Oxygen. (3) Energy.

During exercise the human body needs to react to the increased demand for energy. What changes take place?

A number of changes take place: - The heart rate increases, increasing blood flow to the muscles. - The rate and depth of breathing increase. - Glycogen stored in the muscles is converted back into glucose.

When does Aerobic respiration take place?

Aerobic respiration takes place continuously in both plant and animals.

What is produced when anaerobic respiration happens in plant cells and some microorganisms?

Anaerobic respiration in plant cells and in some microorganisms results in the production of ethanol and carbon dioxide.

What happens if insufficient oxygen reaches the muscles?

If insufficient oxygen is reaching the muscles, energy is produced by anaerobic respiration. - Glucose = lactic acid (+ energy). - C6H12O6 = 2C3H6O3 (+ energy).

Where do most of the reactions in aerobic respiration take place?

Most of the reactions in aerobic respiration takes place in the mitochondria.

During long periods of vigorous activity muscles become fatigued and stop contracting efficiently. What is one of the causes of muscle fatigue?

One cause of muscle fatigue is the build-up of lactic acid in the muscles. Blood flowing through the muscles eventually removes the lactic acid. (Candidates will be expected to interpret data relating to the effects of exercise on the human body)

How can resporation take place in the cells?

Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to release energy.

In which ways is can the energy released during respiration be used by the organism?

The energy that is released during respiration may be used by the organism in a variety of ways: - To build larger molecules from smaller ones. - In animals, to enable muscles to contract. - In mammals and birds, to maintain a steady body temperature in colder surroundings. - In plants, to build up sugars, nitrates, and other nutrients into amino acids, which are then built up into proteins.

What do the changes do to the supply of glucose and oxygen, and what do they do to the carbon dioxide?

These changes increases the supply of glucose and oxygen to the muscles, and increases the rate of removal of carbon dioxide from the muscles.

What is anaerobic respiration?

anaerobic respiration in muscles in muscles is the incomplete breakdown, which causes a build-up of lactic acid. An oxygen debt needs to be repaid to oxidise the lactic acid to carbon dioxide and water.