cell transport

Define 'diffusion'.

Net movement of particles from an area of high to low concentration (down concentration gradient)

What does it mean by 'net movement'?

Overall movement: particles can move in any direction, but generally speaking, most of the particles are moving in one particular direction, hence 'net' movement

State three factors that affect the rate of diffusion.

Concentration gradient, temperature, surface area

How does concentration difference affect the rate of diffusion?

Higher conc difference/Steeper conc gradient

Explain why a higher temperature results in faster diffusion.

More kinetic energy, particles move around more

Name a substance that diffuses into our cells for use.

Oxygen, glucose

Name a substance that diffuses out of our cells to be removed.

Carbon dioxide, urea

Name a structure in the body that is adapted to increase diffusion rate.

Alveoli, villi

Define 'osmosis'.

Net movement of water molecules down the water concentration gradient through a partially permeable membrane

Define 'dilute'.

A solution with a high water conc, but low solute conc

Define 'concentrated'.

A solution with a low water conc, but high solute conc

What are partially permeable membranes?

Membranes that only allow some types of substances to pass through

What is an isotonic solution?

A solution with the same solute conc as the cell

What is a hypertonic solution?

A solution with a higher solute conc than the cell

What is a hypotonic solution?

A solution with a lower solute conc than the cell

If a cell is in a hypertonic solution, water will ___ (enter/leave) the cell.

Leave

If a cell is in a hypotonic solution, water will ___ (enter/leave) the cell.

Enter

What will happen to an animal cell if it is in a hypertonic solution?

Water leaves cell

What will happen to an animal cell if it is in a hypotonic solution?

Water enters cell

Why do animal cells burst in hypotonic solutions?

No cell wall

What will happen to a plant cell if it is in a hypertonic solution?

Water leaves cell

What will happen to a plant cell if it is in an isotonic solution?

No net water movement

What will happen to a plant cell if it is in a hypotonic solution?

Water enters cell

What does 'plasmolysed' mean?

The cell membrane becomes detached from cell wall

Why does the potato skin needs to be removed before putting the potato cylinders into the solutions?

Skin is impermeable

How do we calculate % change in mass?

(final mass

Define 'active transport'.

Movement of particles against the concentration gradient (low to high) using energy in the form of ATP

Explain the importance of active transport in plants.

Root hair cells carry out AT to absorb mineral ions effectively in dilute soil

Explain the importance of active transport in animals.

Cells in gut lining does AT to absorb glucose effectively from the bloodstream

State one adaptations cells may have if they need to carry out active transport.

Lots of mitochondria for respiration for energy

How does active transport differ from diffusion and osmosis?

AT uses energy, D and O do not

State two differences beween diffusion and osmosis.

D: Any particles, does not need a membrane; O: Water specific, needs partially permeable membrane

State the relationship between size and surface area to volume ratio.

The bigger the size, the smaller the SA:V

Describe three adaptations of exchange surfaces.

Large SA, thin membrane/surface, ability to maintain high conc difference

How are alveoli adapted for efficient gaseous exchange?

Large SA, thin membrane (short diffusion distance), rich blood supply (maintain steep conc gradient)