Q 01/05

Which organelle is nicknamed the "powerhouse of the cell"?

A) Mitochondrion

B) Ribosome

C) Nucleus

D) Golgi apparatus

Answer · why

A) Mitochondrion

The mitochondrion has its own DNA, a leftover of its likely origin as a free-living bacterium that an ancient cell engulfed.

Q 02/05

Along with water and light, what do plants need to make their own food through photosynthesis?

A) Nitrogen gas

B) Carbon dioxide

C) Oxygen

D) Hydrogen gas

Answer · why

B) Carbon dioxide

Plants combine carbon dioxide from the air with water, using light energy, to make glucose, and release the oxygen we breathe as a by-product.

Q 03/05

Gregor Mendel worked out the basic rules of inheritance by breeding which plant?

A) Tomatoes

B) Sunflowers

C) Peas

D) Corn

Answer · why

C) Peas

Peas made Mendel famous only after his death: his results were largely ignored until other scientists rediscovered them in 1900.

Q 04/05

What is the basic unit of heredity called?

A) Enzyme

B) Neuron

C) Protein

D) Gene

Answer · why

D) Gene

A gene typically comes in two copies, one inherited from each parent, so every child carries a mix of both parents' versions.

Q 05/05

Which part of the blood carries most of the oxygen from the lungs to the rest of the body?

A) Red cells

B) White cells

C) Platelets

D) Plasma

Answer · why

A) Red cells

Red cells are packed with oxygen-carrying hemoglobin, and in mammals they shed their nucleus as they mature, leaving more room for it.