IGCSE 3rd test

What is a solvent

A solvent is a substance that dissolves a solute to form a solution. It is typically a liquid, but can also exist in gaseous or solid forms.

What is a solute

a solute is a substance that is dissolved in a solvent to create a solution and can be solid, liquid, or gas.

What is a solution

A mixture of one or more solutes dissolved in a solvent is typically a homogeneous liquid.

What is a saturated solution

A saturated solution is a mixture in which the maximum amount of solute has been dissolved in a solvent at a given temperature, resulting in undissolved solute remaining.

What is a residue

A residue is the remaining solid substance after a process such as filtration or evaporation, often found in mixtures.

What is filtrate

Filtrate is the liquid that has passed through a filter during the process of filtration, leaving behind undissolved solids as residue.

What is chromatography used for

To separate mixtures of soluble coloured substances using a suitable solvent

What is the formula for Rf

Rf = distance travelled by substance / distance travelled by solvent

Name 5 methods of purification

solvent extraction, filtration, crystallization, simple distillation, fractional distillation

How can purity be assessed

by comparing the melting or boiling point to know values

Name 3 structures found in plant cells but not in animal cells

cell wall, chloroplast, large vacuole

name 2 structures found in bacterial cells but not in animal or plant cells

circular DNA, plasmids

What is diffusion

The net movement of particles from a region of higher concentration to a region of lower concentration due to random motion, aiming to distribute them evenly

What factors increase diffusion rate

Greater surface area, higher temperature, steeper concentration gradient, shorter distance.

What is osmosis

Net movement of water molecules from a region of higher water potential (dilute) to a region of lower water potential (concentrated) through a partially permeable membrane.

What happens to a plant cell in a dilute solution

becomes turgid due to water intake

What happens to a plant cell in a concentrated solution

becomes flaccid or plasmolysed due to water loss

What is active transport

Movement of particles from low to high concentration (against gradient) using energy from respiration.

Give an example of active transport in plants.

Ion uptake by root hair cells

Give an example of active transport in animals

Absorption of glucose in intestines