Learn: Year Seven Science Flash Cards

Process of science

The study of the natural world through observation and experimentation.

Risk assessment purpose

Identifies potential health risks and practical ways to mitigate them.

Bunsen burner flames

Use the blue flame for heating and the yellow safety flame when idle.

Qualitative vs quantitative data

Qualitative uses descriptive observations; quantitative uses numerical measurements.

Systematic vs random error

Systematic errors are predictable and consistent; random errors vary unpredictably.

Steps of the Scientific Method

Observation, question, hypothesis, experimentation, conclusion, and reporting.

Independent variable

The variable that is intentionally changed or manipulated in an experiment.

Dependent variable

The variable that is measured in response to changes.

Controlled variables

Variables kept constant to ensure a fair test.

Validity in experiments

Whether the test actually measures what it claims to measure.

Matter definition

Any substance that has mass and volume.

Atoms

The smallest unit of matter, consisting of protons, neutrons, and electrons.

Density formula

Density equals mass divided by volume (d = m/V).

Kinetic theory of matter

Describes matter as particles that are continuously moving and interacting.

Pure substance vs mixture

Pure substances have a fixed composition; mixtures contain physically combined substances.

Homogenous vs heterogenous mixture

Homogenous is uniform throughout; heterogenous has visibly different components.

Alloy definition

A homogenous mixture of a metal with other elements.

Solute, solvent, solution

A solute dissolves in a solvent to form a solution.

Solubility definition

The mass of solid required to saturate 100g of water at a given temperature.

Filtration technique

Separates insoluble solids from liquids using a porous barrier.

Chromatography purpose

Separates components of a mixture based on different rates of travel.

Non-contact forces

Forces like magnetic, electrostatic, and gravitational that act through fields.

Mass vs weight

Mass is the amount of matter; weight is the gravitational force acting on mass.

Weight equation

Weight equals mass multiplied by gravitational acceleration (W = mg).

Charging by friction

Electrons transfer between objects rubbed together, creating static charge.

Electromagnet definition

A temporary magnet created by passing electric current through a coiled wire.

Classification purpose

Organizes living things to understand relationships and biodiversity.

Binomial nomenclature

A two-part scientific naming system using genus and species.

Dichotomous key

A tool using paired statements to identify and classify organisms.

Vertebrates vs invertebrates

Vertebrates possess a backbone; invertebrates lack a backbone.

Net force in one dimension

The vector sum of forces acting along a single straight line.

Unbalanced forces effect

Cause an object to accelerate in the direction of the net force.

Newton's first law of motion

An object remains at rest or in uniform motion unless acted upon by a net force.

Inertia definition

The tendency of an object to resist changes in its state of motion.

Newton's second law formula

Force equals mass multiplied by acceleration (F = ma).

Force in a field

Objects with specific properties experience a force when placed in a force field.

Gravitational attraction

All objects with mass are mutually attracted to each other by gravity.

Forces in orbit

Gravity acts as a continuous inward force keeping an object in orbit.

Gravity acceleration consistency

All objects experience the same acceleration due to gravity regardless of mass.

Triboelectric series purpose

Ranks materials to predict which gain or lose electrons during friction.

Electrostatic interactions

Like charges repel each other and opposite charges attract.

Magnetic poles interaction

Like magnetic poles repel and opposite poles attract.

Distance effect on magnets

Magnetic force decreases rapidly as the distance between magnets increases.

Ferromagnetic materials

Materials like iron and nickel that are strongly attracted to magnets.

Electromagnet construction

Wrap a current-carrying wire around an iron core to create a temporary magnet.

Weight force calculation

Multiply mass by gravitational acceleration using the equation W = mg.

Calculating density given mass and volume

Divide mass by volume (d = m / V).

Calculating mass given density and volume

Multiply density by volume (m = d × V).

Calculating volume given mass and density

Divide mass by density (V = m / d).

Density problem example

If mass is 20 g and volume is 10 mL, density is 2 g/mL.

Mass problem example

If density is 3 g/mL and volume is 4 mL, mass is 12 g.

Calculating force given mass and acceleration

Multiply mass by acceleration (F = m × a).

Force problem example

If mass is 5 kg and acceleration is 2 m/s², force is 10 N.

Calculating acceleration given force and mass

Divide force by mass (a = F / m).

Acceleration problem example

If net force is 20 N and mass is 4 kg, acceleration is 5 m/s².

Calculating mass given force and acceleration

Divide force by acceleration (m = F / a).

Six kingdoms of life

Animalia, Plantae, Fungi, Protista, Eubacteria, and Archaebacteria.

Characteristics of living things

Movement, respiration, sensitivity, growth, reproduction, excretion, and nutrition (often remembered as MRS GREN).

Aboriginal and Torres Strait Islander biological classification

A cultural and practical grouping system based on an organism's ecological roles, physical form, seasonal availability, and uses for food, tools, and medicine.

Main plant components

Roots for water absorption and anchoring, stems for structural support and fluid transport, leaves for photosynthesis, and flowers or cones for reproduction.

Adaptation

An inherited characteristic that increases an organism's fitness and likelihood of survival and reproduction in its environment.

Three types of adaptations

Structural (physical body features), physiological (internal biological or chemical functions), and behavioural (actions, routines, or learned responses).

Theory of Evolution by Natural Selection

The mechanism developed by Charles Darwin and Alfred Russel Wallace explaining that individuals with inherited traits best suited to their environment are more likely to survive and pass those traits to offspring.

Ecosystem

A biological community of interacting organisms together with the physical, non-living environment they inhabit.

Habitat

The specific physical place or local environment where an organism lives and finds the resources needed to survive.

Biotic vs abiotic factors

Biotic factors are the living or once-living parts of an ecosystem, while abiotic factors are the non-living physical and chemical components such as sunlight, temperature, and water.

Producers, consumers, and decomposers

Producers make their own food via photosynthesis, consumers obtain energy by feeding on other living things, and decomposers break down dead organic matter to recycle nutrients.

Ecological trophic levels

The sequential feeding positions in an ecosystem: primary producers (plants), primary consumers (herbivores), secondary consumers (carnivores), tertiary consumers (apex predators), and detritivores.

Food chain vs food web

A food chain shows a single linear sequence of energy transfer, whereas a food web is an interconnected network of multiple food chains representing all feeding interactions.

Three main symbiotic relationships

Mutualism (both species benefit), commensalism (one benefits while the other is unaffected), and parasitism (one benefits while harming the host).

Microorganisms vs macroorganisms

Microorganisms are microscopic single-celled or simple organisms like bacteria and fungi that can be beneficial or pathogenic, while macroorganisms are multi-cellular organisms visible without a microscope.

Photosynthesis

The biochemical process in plants that converts carbon dioxide, water, and sunlight into glucose and oxygen ($6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$).

Cellular respiration

The biochemical process in which cells break down glucose and oxygen to release usable cellular energy ($ATP$), yielding carbon dioxide and water as products.

Biodiversity

The variety of all life forms within a given area, encompassing genetic diversity, species diversity, and ecosystem diversity.

Energy flow vs matter flow in ecosystems

Energy flows in one direction through trophic levels and is lost as heat, whereas matter is continually conserved and recycled through biogeochemical cycles.

Carbon cycle

The movement of carbon through photosynthesis, cellular respiration, decomposition, ocean uptake, and fossil fuel combustion across the atmosphere, biosphere, and geosphere.

Nitrogen cycle

The pathway in which atmospheric nitrogen is converted into usable forms by bacteria in soil and root nodules, taken up by plants, consumed by animals, and returned to the atmosphere by denitrifying bacteria.

Anthropogenic impacts on ecosystems

Human-driven disruptions including the enhanced greenhouse effect causing climate change, habitat destruction causing biodiversity loss, and excessive waste generation.

Difference between a scalar and a vector quantity

A scalar has magnitude only, whereas a vector has both magnitude and direction (e.g., force and acceleration).

Scientific definition of force and its standard unit

A push, pull, or twist acting upon an object as a result of an interaction, measured in newtons ($\text{N}$).

Acceleration in terms of velocity

The rate at which an object changes its velocity, which can occur through a change in speed, direction, or both.

Distinction between contact and non-contact forces

One requires physical contact between surfaces (such as friction, tension, and normal force), while the other acts across a distance via force fields (such as gravitational, magnetic, and electrostatic forces).

Normal force direction relative to contacting surfaces

Acts perpendicularly ($90^\circ$) away from the contact surface to support an object resting against it.

Action of friction, drag, and air resistance

Contact forces that act directly opposite to the direction of motion as an object moves across a surface or through a fluid.

Everyday situations where high friction is beneficial

Providing traction between shoe soles and the ground to prevent slipping, vehicle tires gripping the road, and brake pads slowing down wheels.

Balanced forces vs unbalanced forces

Equal and opposite forces produce a net force of $0\,\text{N}$ maintaining constant velocity, while unequal forces produce a non-zero net force that accelerates the object.

Primary mechanical function of simple machines

Reduces the effort force needed to perform work by increasing the distance over which the force is applied or by changing its direction.

Effect of lever arm length on required effort force

Increasing the distance from the pivot (fulcrum) to the applied force reduces the amount of input force required to move a load.

Effect of inclined plane angle on required effort force

Decreasing the slope angle reduces the effort force needed to raise an object by spreading the work over a greater distance.

Mechanical advantage of a pulley system

Distributes the weight of a load across multiple rope segments, thereby decreasing the required pulling force.