Diffusion and active transport — return questions

1. state

Fill the gaps. Diffusion is the ___ movement of particles from a ___ concentration to a ___ concentration, as a result of their ___ movement. It is faster at a ___ temperature.

Overall

Starting concentration

Ending concentration

How the particles move

Temperature that makes it faster

2. calculate

A cube of agar has sides of 5 mm (0.5 cm). Calculate its surface area to volume ratio, in cm⁻¹.

Surface area : volume: ______________ unit ________

3. state

Fill the gaps. Substances move into and out of cells by diffusion through the cell ___. In a leaf, carbon dioxide diffuses in through pores called ___. Many substances can diffuse in living things because they dissolve in water, which is a good ___.

Layer that substances cross

Pores in a leaf

What water is for many substances

4. state

Fill the gaps. Active transport moves particles ___ a concentration gradient. It uses energy released in ___. The particles are carried through the membrane by protein ___.

Direction compared with the gradient

Process that releases the energy

Kind of protein that carries the particles

5. explain

Explain why root hair cells need active transport to take in mineral ions such as nitrate.