Q 01/05

Which form of the process, used by plants and algae, releases oxygen?

A) Retinal-based

B) Anoxygenic

C) Sulfur-splitting

D) Oxygenic

Answer · why

D) Oxygenic

The oxygen comes from splitting water, not carbon dioxide — a fact proved with radioactive isotopes by Ruben and Kamen.

Q 02/05

Which pigment do plants mainly use to absorb light?

A) Chlorophyll

B) Hemoglobin

C) Keratin

D) Melanin

Answer · why

A) Chlorophyll

It absorbs red and blue light and reflects green, which is why leaves look green.

Q 03/05

Why do most plants appear green?

A) Water inside the leaves is naturally that colour

B) Chlorophyll absorbs only that colour of light

C) Chlorophyll reflects that colour instead of absorbing it

D) Plant cell walls are tinted that colour

Answer · why

C) Chlorophyll reflects that colour instead of absorbing it

Chlorophyll's absorption peaks are in the violet-blue and red parts of the spectrum.

Q 04/05

In which organelle does photosynthesis take place in plants and algae?

A) Chloroplast

B) Nucleus

C) Ribosome

D) Mitochondrion

Answer · why

A) Chloroplast

A typical plant cell holds 10 to 100 of them, and a square millimetre of leaf interior can pack up to 800,000.

Q 05/05

What are the stacks of flattened thylakoid discs called?

A) Cristae

B) Lamellae

C) Grana

D) Vacuoles

Answer · why

C) Grana

Each disc is a thylakoid; the fluid around them is the stroma, where the Calvin cycle runs.