Grade 8 EOY Flashcards

Continuous Variation

Variation that changes gradually with no distinct categories, like height, influenced by both genes and the environment.

Discontinuous Variation

Variation that falls into distinct, separate categories with no intermediates, like blood group, controlled only by genes.

DNA

The molecule that carries genetic information and instructions for an organism's traits.

Gene Organization

DNA is wound into genes, which make up chromosomes, all housed inside the cell nucleus.

Sexual Reproduction

Reproduction involving two parents that produces genetically diverse offspring, giving an evolutionary advantage in changing environments.

Asexual Reproduction

Reproduction involving one parent that produces genetically identical clones quickly, but lacks genetic diversity.

Dominant Allele

An allele that always expresses its trait even if only one copy is present (represented by a capital letter).

Recessive Allele

An allele that only expresses its trait when two copies are present (represented by lowercase letters).

Natural Selection

The process where organisms with adaptations best suited to their environment survive, reproduce, and pass on their genes.

Artificial Selection

The process where humans deliberately breed plants or animals for specific desired traits (selective breeding).

MRS GREN

The acronym for the 7 life processes: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.

Phototropism

The growth of a plant towards a light source, controlled by plant hormones.

Five Kingdoms

The classification groups for all living things: Animals, Plants, Fungi, Protists, and Prokaryotes.

Vertebrate vs Invertebrate

Vertebrates are animals that possess a backbone or spinal column; invertebrates lack a backbone.

Biodiversity

The variety of different species living within a specific ecosystem or habitat.

Quadrat and Transect

Quadrats are square frames used for random sampling of organisms; transects are lines used for systematic sampling across an area.

Energy Loss in Food Webs

Energy is lost between trophic levels (usually 90% lost) as heat, through movement, respiration, and undigested waste.

Element

A pure substance made of only one type of atom that cannot be broken down chemically.

Compound

A substance made of two or more different elements chemically bonded together.

Mixture

A combination of two or more substances that are physically blended but not chemically joined.

Properties of Metals

Elements that are typically shiny, malleable, ductile, sonorous, good conductors of heat/electricity, and have high melting points.

Metal Oxide + Water

Reacts to form an alkaline solution (hydroxide) with a high pH, turning Universal Indicator blue or purple.

Non-Metal Oxide + Water

Reacts to form an acidic solution with a low pH, turning Universal Indicator red, orange, or yellow.

Group 1 Metals + Water

Reacts vigorously to produce a metal hydroxide solution and flammable hydrogen gas.

Reactivity Series

A list of metals arranged in order of their reactivity, from most reactive at the top to least reactive at the bottom.

Displacement Reaction

A chemical reaction where a more reactive metal pushes out (displaces) a less reactive metal from its compound.

Metal + Acid

Reacts to produce a salt and hydrogen gas (Metal + Acid -> Salt + Hydrogen).

Oxidation and Reduction

Oxidation is the gain of oxygen during a reaction; reduction is the loss of oxygen (often used to extract metals).

Neutralisation

A reaction between an acid and a base that produces a neutral salt and water.

Thermal Decomposition

The breaking down of a substance (like a metal carbonate) into simpler substances using heat.

Precipitation Reaction

A reaction where two clear solutions react to form an insoluble solid called a precipitate.

Gas Tests

Hydrogen pops with a lighted splint; Carbon Dioxide turns limewater cloudy; Oxygen relights a glowing splint; Chlorine bleaches damp litmus paper.

Exothermic and Endothermic

Exothermic reactions release thermal energy to the surroundings (get hotter); endothermic reactions absorb thermal energy (get colder).

Forms of Energy

The distinct states energy can exist in: kinetic, gravitational potential, chemical, elastic potential, nuclear, thermal, light, sound, and electrical.

Law of Conservation of Energy

Energy cannot be created or destroyed, it can only be transferred from one form to another.

Kinetic Energy Equation

KE = ½mv² (where m is mass in kg, and v is speed in m/s). Measured in Joules (J).

Gravitational Potential Energy Equation

GPE = mgh (where m is mass, g is gravitational field strength, and h is height). Measured in Joules (J).

Efficiency Equation

Efficiency (%) = (Useful Energy Output / Total Energy Input) x 100.

Sankey Diagram

A visual diagram where the width of arrows shows the proportion of energy input, useful energy output, and wasted energy.

Conduction

The transfer of thermal energy through direct contact between particles in a solid.

Convection

The transfer of thermal energy in fluids (liquids and gases) where warm, less dense fluid rises and cool, denser fluid sinks.

Radiation

The transfer of thermal energy via electromagnetic waves that does not require a medium to travel through.

Seasons Cause

The Earth's axial tilt of 23.44 degrees causes different hemispheres to lean toward or away from the Sun during its orbit.

Speed Equation

v = d/t (Speed = Distance divided by Time).

Terminal Velocity

The constant maximum speed reached by a falling object when the upward force of air resistance equals the downward force of weight.