Why does the electron transport chain stop without oxygen?
Oxygen is the terminal electron acceptor at Complex IV. With nothing to accept electrons, the chain backs up and ATP synthesis halts.
The back of a card
lecture-04-cellular-respiration.pdfP.12/28
Each carrier in the chain has a higher reduction potential than the one before it, so electrons move downhill in energy.
Oxygen accepts those electrons at Complex IV and combines with protons to form water.
This is the step that keeps the whole chain turning over.
Three sources, three different pages, three different passages. Each one opens the PDF where it came from.
Always connected to the source
Remka keeps the source, knowledge point, question, and answer together.
What do 1, 2, 3, and 4 mean?
They are not scores. They describe four recall outcomes and also act as keyboard shortcuts in review. Rate the real recall difficulty, not the interval you want.
AGAIN · Recall failed
When to choose it
The answer was wrong or blank, or it only felt familiar after you revealed it.
What FSRS hears
This is the only failing outcome. FSRS records that retrieval did not succeed.
What happens next
The answer was wrong or blank, or it only felt familiar after you revealed it.
If you eventually recalled the correct answer with great effort, choose 2 “Hard”.
Recall failed
HARD · Recalled with effort
When to choose it
You answered correctly, but only after serious hesitation or mental effort, or the answer was barely complete.
What FSRS hears
FSRS treats this as successful recall, but a clearly difficult retrieval.
What happens next
It usually brings the card back sooner than 3 “Good”, so a harder card gets another review earlier.
Do not choose 2 after an incorrect answer. FSRS treats “Hard” as a successful recall.
OK · Normal successful recall
When to choose it
You answered correctly with ordinary thought or a brief pause, without serious struggle.
What FSRS hears
This is a normal successful recall and the usual choice for an ordinarily correct answer.
What happens next
FSRS uses the card’s current difficulty, stability, and review history to calculate its next appearance.
Do not choose 3 because you prefer the displayed interval; describe the real recall experience.
EASY · Effortless successful recall
When to choose it
You answered almost immediately, completely, and confidently, with little or no effort.
What FSRS hears
FSRS treats this as the easiest successful recall.
What happens next
It usually produces the longest of the four intervals, leaving more time for cards you are likelier to forget.
Feeling familiar after revealing the answer is not “Easy”; recall must be effortless before the reveal.
Every card gets its own next review time
Spend review time on the cards you are more likely to forget. Watch the same 24 cards move to different next review times under both schedules.
BEFORE / AFTER
Simplify fixed steps
Revision today0
Today5
Q1Again
Q2Again
Q3Again
Q4Again
Q5Again
Next 7 days11
Q6Hard
Q7Hard
Q8Hard
Q9Hard
Q10Hard
Q11OK
Q12OK
Q13OK
Q14OK
Q15OK
Q16OK
In 7 days0
FSRS-6
Revision today0
Today5
Q1Again
Q2Again
Q3Again
Q4Again
Q5Again
Next 7 days6
Q6Hard
Q7Hard
Q8Hard
Q9Hard
Q10Hard
Q11OK
In 7 days5
Q12OK
Q13OK
Q14OK
Q15OK
Q16OK
