Q 01/05

Which ocean organisms carry out about half of all photosynthesis on Earth?

A) Giant kelp

B) Seagrasses

C) Phytoplankton

D) Mangroves

Answer · why

C) Phytoplankton

Phytoplankton are too small to see one at a time, yet these drifting specks together match the output of every forest, crop and grassland on land.

Q 02/05

Which pigment do plants mainly use to absorb light?

A) Chlorophyll

B) Anthocyanin

C) Lycopene

D) Xanthophyll

Answer · why

A) Chlorophyll

Chlorophyll is so strong a colour that it hides the yellow and orange pigments sitting beside it, which is why they only show once it breaks down in a...

Q 03/05

Why do most plants appear green?

A) Their sap is naturally green

B) Their pigment absorbs only green light

C) Their pigment reflects green light

D) Their cell walls are tinted green

Answer · why

C) Their pigment reflects green light

Their pigment reflects green light: it soaks up red and blue to power the leaf, so the colour we see is the part of sunlight the plant uses least.

Q 04/05

Which plant tissue carries the sugars made in leaves to the roots, fruits and growing tips?

A) Xylem

B) Phloem

C) Cambium

D) Epidermis

Answer · why

B) Phloem

Phloem sap is so sugary that aphids tap it for a living, drinking more than they can use and excreting the surplus as sticky honeydew.

Q 05/05

What are the stacks of flattened thylakoid discs inside a chloroplast called?

A) Cristae

B) Lamellae

C) Grana

D) Vacuoles

Answer · why

C) Grana

Grana look like piles of coins under an electron microscope, and thin membrane bridges join each pile to its neighbours so that all of them work as on...