SAC 1 c) respiration

Question 1

Why do cells require energy?

Answer 1

• movement
• making new material for growth and repair
• detecting and responding to environmental changes
• maintaining their internal conditions

Question 2

Aerobic Respiration

Answer 2

Glucose is oxidised (reacts with O2) to form carbon dioxide + water + ATP is released

Question 3

When does respiration happen?

Answer 3

ALL THE TIME

Question 4

What does respiration provide?

Answer 4

transferring of glucose to ATP

Question 5

structure of a mitochondrion: matrix

Answer 5

fluid filling inside

Question 6

structure of a mitochondrion: cristae

Answer 6

inner membrane

Question 7

what kind of organelle is a mitochondrion

Answer 7

double-membrane organelle

Question 8

stages of aerobic respiration

Answer 8

• Glycolysis
• Krebs cycle
• Electron Transport chain reactions (ETC)

Question 9

glycolysis

Answer 9

• cytosol
• happens regardless of oxygen availability.
• molecule of glucose (6C) is broken down into two molecules of pyruvate/pyruvic acid
• hydrogen (H+) is released from glucose and loaded onto coenzyme NAD (H+ carrier) which becomes NADH
• 2 ATP molecules produced

Question 10

inputs + outputs of krebs cycle

Answer 10

INPUTS: Glucose + 2ADP + 2Pi + 2NAD+
OUTPUTS: 2 Pyruvate + 2 ATP + 2NADH

Question 11

Krebs cycle

Answer 11

• mitochondria - matrix
• pyruvate combines with Coenzyme A to form ACETYL CoA (with release of CO2) (link reaction)
• Acetyl CoA is broken down, releasing protons and electrons.
• these are loaded onto NAD+ and FAD to generate NADH and FADH2
• Three CO2 are produced per glucose molecule
• 2 ATP produced

Question 12

electron transport chain

Answer 12

• oxygen essential
• mitochondria - inner membranes (cristae)
• Hydrogen ions from NADH and FADH2 are transferred along carrier proteins on the cristae and are finally accepted by O2.
• O2 reacts with the hydrogen ions to form WATER (H2O)
• ETC reactions release energy to produce ATP

Question 13

Where do each of the stages occur in a cell?

Answer 13

Glycolysis - cytosol
Krebs cycle - MATRIX of mitochondria
ETC - CRISTAE (inner membrane ) of mitochondria.

Question 14

What are the inputs/outputs for glycolysis?

Answer 14

needed: glucose + 2NAD+ + 2ADP+Pi
produced: 2 pyruvate + 2NADH + 2ATP

Question 15

What are the inputs/outputs for Krebs cycle?

Answer 15

LINK REACTION: PYRUVATE -> ACETYL COA
needed: Acetyl CoA + NAD+ + FAD + 2ADP+Pi
produced: CO2 + FADH2 + 2ATP + NADH

Question 16

What are the inputs/outputs for ETC?

Answer 16

needed: ADP+Pi + NADH + FADH2 + O2
produced: NAD+ + FAD+ +H2O + 26 OR 28 ATP

Question 17

What are NAD and FAD?

Answer 17

NAD - coenzyme, H+ carrier, creates NAD+
FAD - coenzyme, creates FADH2

Question 18

What role do NAD and FAD play in respiration?

Answer 18

cycle between loaded and unloaded states during cellular respiration.
eg. Some reactions require UNLOADED coenzymes to start, but other reactions require input of LOADED coenzymes

Question 19

Where is the most ATP energy produced?

Answer 19

electron transport chain

Question 20

What is the net gain of ATP from one molecule of glucose undergoing respiration?

Answer 20

aerobic: 26 to 28 ATP per glucose molecule
anaerobic: 2 ATP per glucose molecule

Question 21

What are the main differences between aerobic and anaerobic respiration?

Answer 21

aerobic:
- purpose is to transfer energy from glucose to ATP
- cytosol + mitochondria
- produces high ATP yield (36-38 *** ATP per glucose molecule)
- produces carbon dioxide (CO₂) and water (H₂O).
- slower but sustained energy

anaerobic:
- purpose is to make ATP without oxygen
- cytosol
- produces a low ATP yield (2 ATP per glucose molecule)
- produces lactic acid (animals) or ethanol & CO₂ (plants)
- quicker but temporary bc of toxic byproducts

Question 22

Under what conditions does anaerobic respiration occur?

Answer 22

When there is low or no oxygen available

Question 23

What are the products in animals from anaerobic respiration?

Answer 23

lactic acid and ATP

Question 24

worded equation for animals in anaerobic respiration?

Answer 24

Glucose → Lactic acid + ATP

Question 25

Why can’t animals sustain anaerobic respiration for prolonged periods?

Answer 25

In the absence of oxygen, an enzyme converts pyruvate into lactate . lactate builds up in the muscles, the pH falls and pain and muscle fatigue occur…cramps result.

Question 26

What are the products in plants/fungi/bacteria from anaerobic respiration? What other term is used?

Answer 26

Ethanol + Carbon dioxide + ATP also called alcohol/ethanol fermentation

Question 27

difference between anaerobic respiration + fermentation

Answer 27

RESPIRATION: Location - Cytosol & mitochondria Inputs- Glucose, O2 Outputs- CO2, H2O Energy Output- 30-32 ATP per glucose Sustainability: Can continue indefinitely FERMENTATION: Location- Cytosol Inputs- Glucose Outputs- Lactic acid (animals), Ethanol & CO₂ (plants/yeast) Energy Output- 2 ATP per glucose Sustainability: Cannot continue indefinitely *************

Question 28

What is the energy gain from anaerobic respiration?

Answer 28

2ATP (from glycolysis)

Question 29

List the factors that can affect the rate of respiration.

Answer 29

- Temperature & pH - Glucose Availability - O2 concentration - Enzyme inhibition

Question 30

Be able to read and interpret graphs which show how the rate of respiration may be affected by temperature and pH, glucose availability and oxygen concentration.

Question 31

link between enzymes and the rate of photosynthesis

Answer 31

- Enzymes help speed up important reactions in both stages of photosynthesis - factors that affect enzymes affect photosynthesis: a) Temperature: Too high = denatured, too low = slow. b) pH: Alters enzyme efficiency. c) Substrate (CO₂, light): Affects reaction speed. - More active enzymes = faster photosynthesis.