Osmosis Flashcards – AQA GCSE Combined Science: Trilogy (8464) — Biology — Foundation

What is osmosis?

The diffusion of water through a partially permeable membrane.

In which direction is the net movement of water by osmosis between solutions of different concentrations?

From the more dilute solution to the more concentrated solution.

Why can water move into or out of a cell by osmosis?

The cell membrane is partially permeable.

How is the average rate of water uptake calculated?

$\text{Average rate} = \frac{\text{water uptake}}{\text{time taken}}$

What two quantities can be used to measure water uptake?

Mass or volume of water.

How is a compound unit for water uptake rate formed?

Combine the uptake unit with a time unit, such as grams per minute or cubic centimetres per minute.

What must be checked about measurement units before calculating the rate of water uptake?

The measurements must use consistent units.

How is percentage change in mass calculated?

$\frac{\text{final mass} - \text{initial mass}}{\text{initial mass}} \times 100\%$

What do positive and negative percentage changes in mass indicate?

Positive: a gain in mass. Negative: a loss in mass.

How can the magnitude of a percentage change in mass that is negative be reported?

As a positive percentage loss.

What unit requirement applies when calculating percentage change in mass?

The initial and final masses must be expressed in the same unit.

What does a graph represent?

The relationship between measured or calculated quantities.

What should guide the choice of graph type?

The data being represented.

On which axes are the independent and dependent variables normally plotted?

Independent variable: horizontal axis; dependent variable: vertical axis.

What should graph axis labels include?

The quantities and their units.

Why should suitable scales be chosen for graph axes?

To allow the data to be plotted accurately.

How are individual points plotted on a graph?

Using paired values.

After plotting points, what may be added to a graph where appropriate?

A line or curve.

What two activities are involved in interpreting a graph?

Reading values and describing the patterns or relationships shown.