Year 7 Science: Cells, Forces, and Our Solar System

Essential Key Stage 3 / Year 7 science vocabulary flashcards covering the core principles of cell biology, types and effects of forces, and our solar system.

Cell

The basic structural and functional unit of all living organisms.

Nucleus

The organelle in eukaryotic cells that contains genetic material (DNA) and controls the activities of the cell.

Cell Membrane

The semi-permeable barrier surrounding a cell that regulates the movement of substances entering and leaving the cell.

Cytoplasm

A jelly-like fluid inside the cell where cellular structures are suspended and where most chemical reactions take place.

Mitochondria

Organelles found in the cytoplasm where aerobic respiration occurs to release energy for the cell.

Cell Wall

A rigid outer layer made of cellulose found in plant cells that provides structural support and protection.

Chloroplast

A plant cell organelle that contains chlorophyll and absorbs light energy to carry out photosynthesis.

Vacuole

A large fluid-filled cavity in plant cells containing cell sap that maintains internal turgor pressure.

Force

A push or pull exerted on an object that can alter its speed, direction of motion, or shape, measured in Newtons ($\text{N}$).

Gravity

A non-contact attractive force pulling objects with mass toward each other, such as pulling objects toward the center of the Earth.

Friction

A contact force that resists the relative sliding motion between two solid surfaces in contact.

Air Resistance

A frictional drag force exerted by air particles that opposes the forward motion of an object travelling through the air.

Balanced Forces

Opposing forces acting on an object that are equal in magnitude and opposite in direction, resulting in a resultant force of zero and no acceleration.

Unbalanced Forces

Forces acting on an object that do not cancel out, resulting in a non-zero net force that causes the object to accelerate, decelerate, or change direction.

Weight

The gravitational force pulling downward on an object's mass, calculated as $W = m \times g$.

Mass

The quantity of matter contained within an object, measured in kilograms ($\text{kg}$).

Solar System

The gravitationally bound collection of celestial bodies comprising the Sun, eight planets, dwarf planets, moons, asteroids, and comets.

Sun

The star at the center of our solar system that supplies light and thermal energy via nuclear fusion.

Planet

A spherical astronomical body that directly orbits a star, has sufficient mass for its own self-gravity, and has cleared its orbital path of other debris.

Orbit

The regular, gravitationally curved trajectory that an astronomical object follows around another body in space.

Moon

A natural satellite that moves in an orbit around a planet or celestial body.

Asteroid

A small, rocky body orbiting the Sun, with most located in the asteroid belt between Mars and Jupiter.