Q 01/05

Which gas do plants release as a by-product of photosynthesis?

A) Carbon dioxide

B) Oxygen

C) Nitrogen

D) Hydrogen

Answer · why

B) Oxygen

It comes from splitting water molecules, and photosynthesis is what keeps Earth's atmosphere breathable.

Q 02/05

Which part of the cell is nicknamed the 'powerhouse of the cell'?

A) Nucleus

B) Mitochondrion

C) Ribosome

D) Chloroplast

Answer · why

B) Mitochondrion

The nickname was popularised by a 1957 Scientific American article; it makes the energy molecule ATP.

Q 03/05

What is the chemical formula for water?

A) CO2

B) NaCl

C) O2

D) H2O

Answer · why

D) H2O

Two hydrogen atoms and one oxygen atom; it is a polar molecule, which is why it dissolves so many things.

Q 04/05

Who discovered cells in 1665 by looking at a slice of cork under a microscope?

A) Robert Hooke

B) Isaac Newton

C) Galileo Galilei

D) Louis Pasteur

Answer · why

A) Robert Hooke

He named them cells because they reminded him of monks' rooms in a monastery.

Q 05/05

DNA is made of four bases: adenine, guanine, cytosine and which other?

A) Thymine

B) Uracil

C) Glycine

D) Lysine

Answer · why

A) Thymine

The two strands coil into the famous double helix; uracil takes thymine's place in RNA.