Respiration

Question 1

What kind of process is respiration?

Answer 1

It is an exothermic process - it releases energy.

Question 2

What is photosynthesis?

Answer 2

Photosynthesis is the process by which plants, and some bacteria, synthesise food molecules - which they then use, in addition to other things, for respiration. The process of photosynthesis requires energy - it is endothermic.

Question 3

What is breathing or ventilation?

Answer 3

Breathing (ventilation) is the mechanical movement of air in and out of the lungs.

Question 4

What is respiration?

Answer 4

Respiration is the process of releasing energy from glucose to a usable form for the cells (ATP).

Question 5

Why do organisms need energy?

Answer 5

• to drive the chemical reactions needed to keep them alive
• movement
• cell division
• to maintain constant conditions in the cells and the body - homeostasis
• to move molecules against the concentration gradients in active transport
• for the transmission of nerve impulses

Question 6

What is aerobic respiration?

Answer 6

Aerobic respiration is respiration using oxygen to break down food molecules, such as glucose. Glucose is the main respiratory substrate - or the molecule normally used for respiration. Gucose is oxidised to release its energy.

Question 7

Word equation of aerobic respiration

Answer 7

glucose + oxygen —> carbon dioxide + water + energy released

Question 8

Chemical equation for aerobic respiration

Answer 8

C6H12O6 + 6O2 —> 6CO2 + 6H2O + energy released

Question 9

Where does aerobic respiration occur?

Answer 9

The first stages of respiration occur in the cytoplasm of cells, but most of the energy is released in the mirchendria.

Question 10

What is anaerobic respiration?

Answer 10

Most organisms cannot respire without oxygen but some organisms and tissues can continue to respire if oxygen runs out; this is known as anaerobic respiraton.
Human muscle can respire anaerobically for short periods of time.

Question 11

Anaerobic respiration in animals word equation

Answer 11

glucose —> lactic acid + energy released

Question 12

Anaerobic respiration in animals chemical equation

Answer 12

C6H12O6 —> 2C3H6O3 + energy released

Question 13

Anaerobic respiration in yeast (fermentation) word equation

Answer 13

glucose —> ethanol + carbon dioxide + energy released

Question 14

Anaerobic respiration in yeast (fermentation) chemical equation

Answer 14

C6H12O6 —> 2C2H5OH + 2CO2 + energy released

Question 15

Where does anaerobic respiration occur?

Answer 15

Cytoplasm

Question 16

Aerobic Respiration Vs Anaerobic Respiration

Answer 16

Aerobic:
- Presence of oxygen
- Complete oxidisation of glucose
- Relatively large amount of energy released
- Slower but releases more energy
- More frequent

Anaerobic:
- Absence or short supply of oxygen
- Incomplete oxidisation of glucose
- Small amount of energy released
- Faster but less energy released
- Less frequent

Question 17

Photosynthesis word equation

Answer 17

carbon dioxide + water - sunlight + chlorophyll -> glucose + oxygen

Question 18

Photosynthesis chemical equation

Answer 18

6CO2 + 6H2O —> C6H12O6 + 6O2

Question 19

What is the response to exercise?

Answer 19

Muscles need energy to contract. While exercising, the muscles need additional energy as:
—> the breathing rate and volume of each breath increases
—> the heart rate increases

Question 20

What happens during long periods of vigorous exercise?

Answer 20

—> lactic acid levels build up
—> glycogen reserves in the muscles become low as more glucose is used for respiration, and additional glucose is transported from the liver

Question 21

What are the side effects of anaerobic respiration?

Answer 21

Build up of lactic acid produces oxygen debt
As body stores of glycogen become low, a person suffers from muscle fatigue

Question 22

What happens when a period of exercise is over?

Answer 22

Lactic acid must be removed, as the body’s tolerance of lactic acid is limited.

Question 23

How is lactic acid removed?

Answer 23

Lactic acid is taken to the liver by the blood, and either:
- oxidised to carbon dioxide and water, or
- converted to glucose, then glycogen, for levels in the liver and muscles to be restored

Question 24

What happens to breathing rate after exercise?

Answer 24

The removal of lactic acid requires oxygen, hence, after exercise, you continue to breathe deeply and quickly for a short period of time, known as EPOC (excess post-exercise oxygen consumption).

Question 25

What is oxygen debt?

Answer 25

The amount of oxygen required to remove lactic acid post-exercise.