2.8 Cell Respiration

Question 1

Cell respiration

Answer 1

the controlled release of energy from organic compounds to produce ATP.

Question 2

cell respiration formula

Answer 2

C6H12O6 + 6O2 —–> 6CO2 + 6H2O
glucose + oxygen —–> carbon dioxide and water

Question 3

ATP stands for

Answer 3

adenosine triphosphate

Question 4

ATP cannot leave the cell, so…

Answer 4

every cell must make their own supply

Question 5

heat energy in ATP

Answer 5

ATP used in cells creates heat that can keep organism warm but this is lost to environment so ATP must be continus supply

Question 6

ATP is needed for

Answer 6

• synthesizing large molecules like DNA, RNA and proteins
• pumping molecules or ions across membranes by active transport
• moving thinhgs around inside the cell or for muscle contractions

Question 7

When ATP is hydrolysed (to form ADP + Pi)….

Answer 7

the energy stored in the phophate bond is released to be used by the cell

Question 8

Cell respiration uses energy stored in organic molecules to ….

Answer 8

regenerate ATP from ADP + Pi (via oxidation)

Question 9

Glycolysis

Answer 9

1st stage for both types of respiration.

Location: Cytoplasm of the cell.

Glucose molecules are broken down into pyruvate molecules with the release of a small amount of energy (2 ATP).

Question 10

Aerobic cell respiration

Answer 10

Pyruvate from glycolysis moves to the Mitochondria.

Inside the mitochondria the pyruvate is broken down into carbon dioxide and water.

A large amount of ATP is produced (about 36 ATP).

• The water can be useful – some desert animals never need to drink as respiration provides all the water they need!

Question 11

Anaerobic cell respiration

Answer 11

When O2 is not available, anaerobic respiration may occur.

In the absence of oxygen, glucose can only be partially broken down, there will be less energy available to the cell.

Pyruvate must be broken down somehow for cell respiration to continue

The name given to these anaerobic processes is Fermentation.

Question 12

Alcohol fermentation:

Answer 12

Which occurs in plants and yeasts.
pyruvate —-> ethanol + carbon dioxide

Question 13

Lactate fermentation:

Answer 13

Which occurs in animals.
pyruvate —-> lactate (lactic acid)

Question 14

electron carrier, NAD+ is regenerated…

Answer 14

the cycle can continue in the absence of oxygen, allows glycolysis and fermentation to continue, producing only 2 ATP each time (from glycolysis).

Question 15

uses of alcohol fermentation

Answer 15

Bread – Carbon dioxide causes dough to rise (leavening), the ethanol evaporates during baking
bioethanol- ethanol produced from yeasts is used as fuel in vehicles

Question 16

naerobic respiration can supply ATP

Answer 16

very rapidly, as oxygen is not required

Question 17

Rapid generation of ATP enables us to

Answer 17

maximise the power of muscle contractions

Question 18

Afterwards lactate must be broken down….

Answer 18

This involves the use of oxygen. It can take several minutes for enough oxygen to be absorbed for all lactate to be broken down. The demand for oxygen that builds up during a period of anaerobic respiration is called the oxygen debt.

Question 19

Anaerobic cell respiration produces lactate….

Answer 19

here is a limit to the concentration that the body can tolerate and this limits how much or how long anaerobic respiration can be done for.