Year 8 Science: Energy, Living Systems, and Atomic Structure

Comprehensive practice flashcards covering Year 8 Science topics: forms of energy, heat transfer, atomic structure, the periodic table, living systems, and working scientifically skills.

What is the definition of Energy

The ability to do work.

What is the Law of Conservation of Energy

Energy cant be created or destroyed it can only be transferred or transformed

Kinetic Energy

The energy an object has due to motion, such as a car driving down a road or a ball rolling down a hill.

Gravitational Potential Energy

The stored energy an object has due to its position, such as a book on a high shelf or a roller coaster at the top of a hill.

Chemical Potential Energy

The energy stored within the chemical bonds of atoms and molecules, such as that found in food or fuel.

Elastic Potential Energy

The energy stored in an elastic object due to an applied force that has deformed it through twisting, stretching, or compressing (e.g., a stretched elastic band or the surface of a trampoline).

Nuclear Potential Energy

The energy stored within the nucleus of an atom due to the position of its particles and the forces holding them together, seen in nuclear fusion and nuclear decay.

Heat Energy

The total kinetic energy of the particles that make up a substance. Faster particle vibrations mean more kinetic and heat energy, while the overall amount depends on both temperature and size.

Subatomic Particles

The three constituent particles of an atom: protons (located in the nucleus), neutrons (located in the nucleus), and electrons (which orbit the nucleus).

Electric Circuit Mandatory Components

The three components that every electric circuit must contain: a power supply (e.g., battery or cell), a load that transforms electrical energy (e.g., a light), and a conductive path (e.g., wires).

Conduction

The transfer of energy or heat through a material by direct physical contact (e.g., a metal spoon heating up in a hot drink or walking barefoot on a hot surface).

Convection

The transfer of heat by the movement of a fluid (a liquid or a gas), creating circulating convection currents (e.g., boiling water in a pot or a hot air balloon rising).

Scientific Problem

A scientific question that can be answered via an experimental investigation, such as determining if darker colours absorb more heat than lighter colours when exposed to a light source.

Hypothesis

A predictive statement answering a scientific question based on prior knowledge, research, or observations, formatted as an "If…, then…" statement.

Year 8 Science Yearly Examination Format

A 90-minute assessment plus 5 minutes reading time worth 31% (60 total marks), divided into Section I (15 multiple choice questions, 15 marks), Section II (10 one-word answer questions, 10 marks), and Section III (short answer questions, 35 marks).

Levels of Organisation

The biological structural hierarchy arranged from simplest to most complex: cells $\rightarrow$ tissues $\rightarrow$ organs $\rightarrow$ organ systems.

Digestive System Main Function

To break large, complex food molecules into smaller ones that can cross the lining of the digestive tract and enter the blood.

Peristalsis

The wave-like muscular contraction and movement that pushes food along the digestive tract, functioning even when lying down or upside down.

Cellular Respiration

The chemical process releasing energy for cells: $\text{glucose} + \text{oxygen} \rightarrow \text{energy} + \text{carbon dioxide} + \text{water}$.

Nephron

The functional unit of the kidney responsible for filtering blood and controlling the composition of body fluid.

Pathway of Urine

The route taken by urine through the urinary system: kidneys $\rightarrow$ ureters $\rightarrow$ bladder $\rightarrow$ urethra.

Components of Blood

The four constituents of blood: red blood cells, white blood cells, plasma, and platelets.

Xylem and Phloem

Specialised vascular transport tissues in plant stems; xylem transports water and minerals from the roots, whereas phloem transports sugars.

Atom

The smallest unit of an element that retains the chemical properties of that element, composed of protons, neutrons, and electrons.

Physical Properties of Metals

Key physical characteristics of metallic elements, including being malleable, ductile, highly conductive of heat and electricity, and lustrous (shiny).

Physical Properties of Non-metals

Key physical characteristics of non-metallic elements, typically being brittle, dull in appearance, and poor conductors of heat and electricity.

Metalloids

Elements positioned between metals and non-metals on the periodic table whose physical properties are an intermediate mix of metals and non-metals.

Periodic Table Group Property Trend

Elements located in the same vertical group share similar chemical properties.

Periodic Table Atomic Radius Trend

Atomic radius decreases moving across a period from left to right and increases moving down a group.

Exothermic Reaction

A chemical reaction that releases energy to its surroundings.

Endothermic Reaction

A chemical reaction that absorbs energy from its surroundings.

Mean (Data Analysis)

A statistical average calculated by adding all individual values in a dataset and dividing by the total number of values.

Range (Data Analysis)

A measure of data dispersion calculated by subtracting the lowest recorded value from the highest value.

Formation of Organ Systems

Similar cells group together to form tissues, different tissues cooperate to form organs, and related organs work together to create an organ system.

Importance of Cell Health in Living Systems

Cells must stay healthy to form strong, functioning tissues, which in turn enable organs to work properly and maintain life.

Mechanical vs Chemical Digestion

Mechanical digestion physically breaks food into smaller pieces without chemical changes (e.g., chewing), while chemical digestion uses digestive enzymes and acids to break complex molecules into simpler nutrients.

Role of Surface Area in Digestion

Chewing and the folded structures of the intestines (villi) increase surface area, allowing digestive enzymes to break down food faster and the blood to absorb nutrients more efficiently.

Uses of Energy Released by Cellular Respiration

Provides energy for bodily movement, cellular growth and repair, synthesis of new molecules, maintaining stable body temperature, and active transport within cells.

Risk Assessment in Scientific Investigations

A planning tool completed before, during, and after an experiment that identifies potential hazards, assesses associated risks, and details control measures to ensure safety.

Energy Unit Conversions

Relationships used to convert nutritional and physical energy values: $1\,\text{kJ} = 1000\,\text{J}$, $1\,\text{cal} \approx 4.184\,\text{J}$, $1\,\text{kcal} = 1000\,\text{cal}$, and $1\,\text{Cal} = 1\,\text{kcal}$.

Essential Features of a Scientific Graph

A clear descriptive title, appropriately labelled axes with units, an even and accurate scale, correctly plotted points, and a line or curve of best fit.

Selection of Suitable Graph Types (Line, Bar, Pie)

Line graphs are used for continuous data showing relationships or trends; bar graphs compare discrete or categorical data; and pie charts display proportional parts of a whole.

Role of the Respiratory System

To supply oxygen to the blood for distribution to cells for cellular respiration, and to remove carbon dioxide waste produced by cellular metabolism.

Key Organs of the Respiratory System

Nostrils, pharynx (throat), epiglottis (flap preventing food entry into airway), larynx (voice box), trachea (windpipe), bronchi, bronchioles, alveoli, and the diaphragm muscle.

Mechanism of Breathing (Inhalation and Exhalation)

Inhalation occurs when the diaphragm contracts and moves downward, expanding lung volume and pulling air in; exhalation occurs when the diaphragm relaxes and moves upward, decreasing volume and forcing air out.

Gas Exchange in the Alveoli

Oxygen diffuses across the thin, moist walls of the alveoli into surrounding blood capillaries, while carbon dioxide diffuses from capillary blood into the alveoli to be exhaled.

Role of the Circulatory System

To transport blood carrying oxygen, nutrients, hormones, and cellular waste products throughout the body, functionally linking all organ systems.

Types of Blood Vessels and Their Functions

Arteries carry high-pressure oxygenated blood away from the heart, veins return lower-pressure blood to the heart using internal valves, and capillaries allow exchange of substances between blood and tissues.

Systemic and Pulmonary Pathway of Blood

Deoxygenated blood flows from body tissues into the right side of the heart, goes to the lungs to pick up oxygen, returns to the left side of the heart, and is pumped via the aorta out to the rest of the body.

Major Organs of the Excretory System

The kidneys, ureters, urinary bladder, and urethra, alongside non-urinary excretory organs including the lungs, liver, and skin.