levo

Energy Systems

The aerobic system and fuel use

  • 3 things to know
  • Component 1

Overview

Pyruvic acid, the Krebs cycle and the electron transport chain, the total ATP yield, beta-oxidation of fat, the fuel mix by intensity, the respiratory exchange ratio, by-products, and the three pathways ranked by speed, amount and force.

What you need to know

Answer each one before you reveal it.

Your recallNot started
Key term

Describe the Krebs cycle.

Key term

What happens in the electron transport chain?

Process

Where do the stages of the aerobic system take place?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    Where do the stages of the aerobic system take place?

    Model answer

    Aerobic glycolysis occurs in the sarcoplasm. The Krebs cycle and the electron transport chain occur in the mitochondria.

  2. 2

    What happens to pyruvic acid when enough oxygen is available?

    Model answer

    Pyruvic acid is converted into acetyl coenzyme A. The acetyl coenzyme A enters the Krebs cycle in the matrix of the mitochondria.

  3. 3

    Describe the Krebs cycle.

    Model answer

    Acetyl coenzyme A combines with oxaloacetic acid to form citric acid. The citric acid is broken down in a cycle of reactions. The cycle resynthesises two ATP and releases carbon dioxide and hydrogen.

  4. 4

    What happens in the electron transport chain?

    Model answer

    Hydrogen carriers (NAD and FAD) deliver hydrogen to the cristae of the mitochondria. Electrons passed along the chain release energy to resynthesise 34 ATP. The hydrogen combines with oxygen to form water.

  5. 5

    What is the total ATP yield of the aerobic system from one molecule of glucose?

    Model answer

    The aerobic system yields about 38 ATP per molecule of glucose. Glycolysis gives two, the Krebs cycle two and the electron transport chain 34.

  6. 6

    What is beta-oxidation?

    Model answer

    Lipase first splits stored triglycerides into glycerol and free fatty acids. Beta-oxidation then breaks the fatty acids down into acetyl coenzyme A, which enters the Krebs cycle.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.

1Closed book
2Open book
3Closed book

The 3-step method, run for you

Answer cold, learn it, then prove it stuck. Levo tracks the jump between your first attempt and your last.

The Musculo-Skeletal System
Levers, Newton's Laws and Stability
The Respiratory System
The Cardiovascular System

Cram a whole paper in one sitting

Sort every topic into what you know and what you do not, then drill only the weak ones.

The survey began in .
201520052012

Blank Blitz makes facts automatic

Rapid timed gap-fills on the terms and numbers you need to recall without thinking.

AThe training zone is 136 to 158 bpm.
BHeart rate reserve = (220 − 40) − 70 = 110 bpm.
CLower limit = (110 × 0.6) + 70 = 136 bpm.

Build It gets the exam shape right

Assemble a full-mark answer from its marking points, in the order an examiner wants them.

Acceleration means a rise in velocity each second.
TrueFalse

Test It catches misconceptions

Spot the fault in a statement. The traps are the mistakes students actually make.

721941163128510

Brain Breaks between sessions

Short focus games to reset attention, so the next set lands better than the last.

Every question in Energy Systems, on a schedule.

Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.

Or £46 a year, about £3.83 a month. Cancel anytime.