2.8 Cellular Respiration

Question 1

cell respiration

Answer 1

• series of metabolic reactions that convert biochemical energy from organic molecules into adenosine triphosphate (ATP), and then release waste products

Question 2

reaction for cellular respiration

Answer 2

Question 3

types of organic compounds used in cellular respiration by animals and plants.

Answer 3

• carbohydrate glucose
• lipids and proteins can also be used if glucose is not readily available to the cell

Question 4

3 example uses of cellular energy

Answer 4

ATP can be used throughout the cell to:
- power active transport
- synthesize polymers
- move structures within the cell

Question 5

energy transfer in the formation and use of ATP

Answer 5

• energy is released when a phosphate group is removed from ATP in a hydrolysis reaction
• reverse reaction (what happens in cellular respiration) regenerates ATP and requires energy input

Question 6

3 reasons why cellular respiration must be continuously performed by all cells

Answer 6

1. ATP can not be stored for later use
2. ATP can not be transferred from cell to cell
3. Heat energy is released when ATP is used in cells. This heat energy can not be reused and will be lost to the environment

Question 7

anaerobic respiration

Answer 7

type of cellular respiration that does not use oxygen

Question 8

3 situations in which anaerobic respiration is useful

Answer 8

1) when cellular oxygen is depleted since it anaerobic respiration can act as a backup
e.g. when muscle cells use up oxygen faster than it can be replenished, the cells start to perform anaerobic respiration in order to keep muscles moving

2) when ATP is needed quickly since anaerobic respiration is more rapid than aerobic respiration

3) Anaerobic metabolism allows microbes to inhabit low-oxygen or oxygen-free environments which allows them to exploit an otherwise empty habitat

Question 9

[COMPARE] anaerobic respiration in yeasts and humans

Answer 9

• both start with glycolysis where glucose is broken down into pyruvate and NADH and ATP are created
• NADH is recycled into NAD+
• both reactions net 2 molecules of ATP

[difference]
- yeast: alcohol fermentation, pyruvate is converted to ethanol, CO2 is released
- humans: lactic acid fermentation, pyruvate is converted into lactic acid

Question 10

[COMPARE] total amount of ATP made from anaerobic and aerobic respiration

Answer 10

• anaerobic respiration: produces a net of 2 ATPs per molecule of glucose
• aerobic respiration: produces up to 38 ATPs per molecule of glucose

Question 11

location of aerobic respiration

Answer 11

• mitochondria

Question 12

how anaerobic respiration in yeast is used in baking

Answer 12

bubbles of carbon dioxide gas, one of the products of anaerobic respiration, expand the dough and help the bread rise

Question 13

how anaerobic respiration in yeast is used in ethanol production

Answer 13

ethanol is one of the products of anaerobic respiration.

Question 14

condition in which humans would perform anaerobic respiration

Answer 14

• when exercising at high intensity, cell demand will exceed available supplies of O2 -> Muscle cells will start breaking down glucose anaerobically to supply ATP rapidly for a short period of time
• Red blood cells do not have mitochondria, so anaerobic respiration always happens

Question 15

production of lactate in humans during anaerobic respiration

Answer 15

• in lactic acid fermentation, NADH produced in glycolysis transfers its electrons directly to pyruvate, generating lactate as a byproduct

Question 16

use of a respirometer to measure cellular respiration rate

Answer 16

• living specimen is enclosed in a sealed container
• oxygen use or carbon dioxide production can be measured directly with a data logger
• alternatively, changes in pressure can be measured. the change in pressure can be measured with a data logger or U-tube manometer

Question 17

ethical questions that must be considered before using animals in experiments

Answer 17

1) purpose of the experiment must have some benefit
2) overall use of animals should be minimized. Alternative methods should be used if available
3) Pain and distress must be minimized

Question 17

ethical questions that must be considered before using animals in experiments

Answer 17

1) purpose of the experiment must have some benefit
2) overall use of animals should be minimized. Alternative methods should be used if available
3) Pain and distress must be minimized