Year 7 Science — Term 4 Study Notes: Cells, Matter, Solutions, and Skills

Comprehensive vocabulary flashcards covering Year 7 Science Term 4 topics, including cells and classification, particle theory and states of matter, solutions, separation techniques, and experimental scientific variables.

MRS GREN

An acronym representing the seven essential life processes carried out by living things: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, and Nutrition.

Classification

Organising living things into groups based on their similarities and differences to identify, communicate about, and understand relationships between organisms.

Binomial Nomenclature

The system of naming species using a two-part scientific name consisting of the Genus (capitalised) and species (lowercase), which is italicised when typed or underlined when handwritten.

Dichotomous Key

A classification tool used to identify an unknown organism where the user chooses between two options at each step until the organism is identified.

Cell Theory

A foundational biological principle consisting of three main ideas: all living things are made of one or more cells, the cell is the basic unit of life, and all cells come from pre-existing cells.

Cell Membrane

A cellular structure found in both plant and animal cells that acts like a security gate to control what enters and leaves the cell.

Cytoplasm

A jelly-like substance within cells where many chemical reactions occur.

Nucleus

The control centre of a eukaryotic cell that contains DNA and controls cellular activities.

Mitochondria

Organelles that act as the cell's energy station, serving as the site of cellular respiration where usable energy is released.

Cell Wall

A rigid outer structure mainly associated with plant cells that supports and strengthens the cell.

Chloroplasts

Organelles in plant cells that serve as the site of photosynthesis and contain chlorophyll, which absorbs light energy.

Large Permanent Vacuole

An organelle found in plant cells that contains cell sap and helps maintain internal cell pressure.

Photosynthesis

The chemical process occurring in chloroplasts where plants use light energy, chlorophyll, carbon dioxide, and water to produce glucose and oxygen ($\text{Carbon dioxide} + \text{water} \rightarrow \text{glucose} + \text{oxygen}$).

Cellular Respiration

The chemical process occurring mainly in mitochondria that releases usable energy from glucose ($\text{Glucose} + \text{oxygen} \rightarrow \text{carbon dioxide} + \text{water} + \text{energy}$).

Prokaryotic Cell

A cell, such as a bacterium, that does not have a nucleus enclosed by a membrane.

Eukaryotic Cell

A cell that contains a distinct, membrane-enclosed nucleus, such as plant, animal, and fungal cells.

Specialised Cell

A cell that possesses a specific structure adapted to perform a particular function.

Tissue

A group of similar specialised cells working together to perform a specific function.

Organ

A structure composed of different tissues working together to carry out a particular function.

Sublimation

A physical change of state where a solid turns directly into a gas without passing through the liquid phase.

Deposition

A physical change of state where a gas turns directly into a solid without passing through the liquid phase.

Density

A measure of mass per unit volume, calculated using the formula $\rho = \frac{m}{V}$.

Buoyancy

The upward force exerted by a fluid on an object placed in it.

Surface Tension

A property caused by cohesive attractive forces between particles at the surface of a liquid.

Solute

The substance that dissolves in a solvent to form a solution.

Solvent

The substance that does the dissolving in a solution.

Solution

A uniform mixture formed when a solute completely dissolves in a solvent.

Solubility

The ability of a substance to dissolve in a particular solvent under specified conditions.

Dilute Solution

A solution that contains a relatively small amount of dissolved solute compared to the volume of solvent.

Concentrated Solution

A solution that contains a relatively large amount of dissolved solute compared to the volume of solvent.

Saturated Solution

A solution that contains the maximum amount of dissolved solute possible under its current conditions.

Supersaturated Solution

An unstable solution that contains more dissolved solute than normally possible under its current conditions.

Pure Substance

A substance that contains only one type of particle, existing either as an element or as a compound.

Element

A pure substance that contains only one type of atom.

Compound

A substance that contains two or more different types of atoms chemically bonded together.

Mixture

A combination of two or more substances that are physically combined rather than chemically bonded.

Filtration

A separation technique that separates an insoluble solid from a liquid based on particle size and insolubility.

Distillation

A separation technique that separates substances in a liquid mixture based on differences in their boiling points.

Decanting

A separation process that involves carefully pouring a liquid away from a solid that has settled at the bottom.

Sieving

A separation technique that separates a mixture of solid particles based on differences in their particle sizes.

Magnetic Separation

A technique that uses magnetism to separate magnetic materials from non-magnetic substances.

Independent Variable

The variable that is deliberately changed or manipulated by the experimenter during an investigation.

Dependent Variable

The variable that is observed and measured to see the effect of changing the independent variable.

Controlled Variables

All conditions and factors kept constant throughout an experiment to ensure a fair and valid test.