Catching light in the thylakoid

Science · Organisms & Life Processes · ages 16-17

Name ______________________ Date ____________

What gas is released when water is split?
- Carbon dioxide
- Nitrogen
- Oxygen
Where do the light-dependent reactions run?
- In the stroma
- In the thylakoid membrane
- In the cytoplasm
The light-dependent reactions make ATP and reduced NADP.
Circle one: True False
How is the proton gradient cashed in?
- Through ATP synthase
- It fixes carbon dioxide
- It splits more water
Why must this stage sit in a membrane?
- Pigments need light, which membranes store
- To build a proton gradient
- To keep oxygen away from chlorophyll
Which pair carries energy and reducing power onward?
- Glucose and oxygen
- Water and oxygen
- ATP and reduced NADP
A student says thylakoids release carbon dioxide. What is wrong?
- They release oxygen
- They release nitrogen instead
- They release nothing at all
Sugar production stops within minutes of lights-out. What best explains it?
- Carrier stocks run dry
- Chlorophyll is used up in the dark
- Water runs out at night

Answer key

For grown-ups. Fold this page away before handing over the rest.

Oxygen · Split water gives oxygen as its byproduct.
In the thylakoid membrane · They sit where the pigments are: the thylakoid membrane.
True · Charging those two carriers is the whole job of this stage.
Through ATP synthase · Protons flowing back through ATP synthase build ATP.
To build a proton gradient · Only a sealed membrane can hold a proton gradient.
ATP and reduced NADP · Those two charged carriers feed the stroma reactions.
They release oxygen · Here, split water gives oxygen.
Carrier stocks run dry · With no light, the stocks drain and the next stage stalls.