Limiting factors and rate of photosynthesis
Practice Flashcards
Flip to reveal answersWhat is a limiting factor?
Track your progress — Sign up free to save your progress and get smart review reminders based on spaced repetition.
All 12 Flashcards — Limiting factors and rate of photosynthesis
Sign up free to track progress and get spaced-repetition review schedules.
Question
What is a limiting factor?
Answer
The factor in **shortest supply** that holds back the rate of a process. Only raising it can increase the rate.
Question
Name the three limiting factors of photosynthesis.
Answer
**Light intensity**, **carbon dioxide concentration** and **temperature**.
Question
Why does only the limiting factor change the rate?
Answer
Because it is the one in shortest supply; the others are already plentiful, so adding more of them does nothing.
Question
On a rate-vs-light graph, what is limiting on the rising part?
Answer
**Light intensity** — while the curve climbs, increasing light increases the rate.
Question
On a rate-vs-light graph, what is limiting on the plateau?
Answer
**CO₂ concentration** (or **temperature**) — light is no longer limiting once the rate goes flat.
Question
Why does a rate-vs-light curve plateau?
Answer
Because **light is no longer the limiting factor**; another factor (CO₂ or temperature) now limits the rate.
Question
On a graph with two CO₂ levels, what does the higher-CO₂ curve do?
Answer
It **plateaus higher up** — more CO₂ lets light keep raising the rate for longer.
Question
How does increasing CO₂ affect the rate while CO₂ is limiting?
Answer
It **increases** the rate, because CO₂ is a raw material that was in short supply.
Question
What happens to the rate if temperature rises too far above the optimum?
Answer
The rate **falls** (and can drop to zero) because the **enzymes denature**.
Question
Why does very high temperature lower the rate of photosynthesis?
Answer
Photosynthesis uses **enzymes**, and high temperature **denatures** them, destroying their shape so they stop working.
Question
How do you spot the limiting factor from a curve's shape?
Answer
If the curve is **sloping**, the factor on the axis is limiting; if it is **flat**, something else is limiting.
Question
Define the 'rate of photosynthesis'.
Answer
How fast photosynthesis happens — e.g. the volume of oxygen released or CO₂ taken up per minute.
Read the notes
Full study notes for Limiting factors and rate of photosynthesis
Topic 3.3 hub
Photosynthesis
More from Topic 3.3
All flashcards in this topic
Biology exam skills
Paper structures & tips
Track your progress with spaced repetition
Sign up free — Aimnova tells you exactly which cards to review and when, so you remember everything before your IB exam.
Start Free