Science EOY Revision

HEALTH: 

Ball-and-Socket and Hinge Joints 

• Ball-and-Socket Joint: Found in areas like the shoulder and hip, this joint allows for a wide range of motion in all directions. One bone's ball-shaped head fits into another's cup-like socket, enabling rotation, swinging, and movement in multiple planes. 

• Hinge Joint: Found in areas like the elbow and knee, this joint allows movement in one plane, like the opening and closing of a door (e.g., bending and straightening). Movement is restricted to back and forth. 

Antagonistic Muscles at a Hinge Joint 

Antagonistic muscles work in pairs to move bones at a hinge joint: 

• Biceps and Triceps at the elbow are examples of antagonistic pairs: 

• When the biceps contract, the triceps relax, pulling the forearm up (flexion). 

• When the triceps contract, the biceps relax, straightening the arm (extension).  

• This coordinated muscle action enables controlled movement at the hinge joint. 

An antagonistic muscle refers to a muscle that works in opposition to another muscle to create movement. Muscles can only pull, not push, so they work in pairs to allow for a full range of motion. In an antagonistic pair, one muscle contracts (the agonist) to produce movement, while the other muscle relaxes and lengthens (the antagonist) to allow that movement. When the motion needs to be reversed, the roles switch—the previous antagonist contracts, becoming the new agonist, and the previous agonist relaxes. 

Bone Marrow 

Function: Produces blood cells (red blood cells, white blood cells, and platelets). 

Types: 

· Red Marrow: Active in blood cell production. 

· Yellow Marrow: Mainly fat storage; can convert to red marrow if needed. 

Ligaments 

Function: Connects bone to bone; provides stability to joints. 

Nerves 

Function: Transmits signals between the brain and body; facilitates movement and sensation. 

Tendons 

Function: Connects muscle to bone; transmits the force generated by muscles to facilitate movement. 

Energy Storage in Animals: 

• Carbohydrates and fats are stored as energy reserves in the body: 

• Carbohydrates are stored as glycogen in muscles and the liver. 

• Fats are stored in adipose tissues and can be broken down for energy when needed. Animals consume food to obtain the energy and nutrients needed for daily functions. 

Diet: A poor diet lacking essential nutrients can stunt growth, weaken the immune system, and lead to obesity or malnutrition. 

Anaerobic Respiration: 

•   Occurs without oxygen. 

   In animals: 

•    Word equation: Glucose → Lactic acid + Energy 

•    Chemical equation: C₆H₁₂O₆ → 2C₃H₆O₃ + ATP 

   In plants/yeast: 

•    Word equation: Glucose → Ethanol + Carbon dioxide + Energy 

•    Chemical equation: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂ + ATP 

BREATHING:  

1. Inhalation: 

•    The diaphragm contracts and flattens, creating more space in the chest cavity. 

•    Air enters through the nose or mouth, travels down the trachea, and reaches the lungs. 

2. Air in the Lungs: 

• Air moves into bronchi, then into smaller bronchioles, and finally into alveoli (tiny air sacs). 

• In the alveoli, oxygen from the air diffuses into the bloodstream, while carbon dioxide from the blood diffuses into the alveoli. 

3. Exhalation: 

• The diaphragm relaxes, decreasing chest space. 

• Carbon dioxide is expelled from the lungs as air is breathed out. 

Lung Structure: The lungs contain millions of alveoli (tiny air sacs) that provide a large surface area for gas exchange. 

Diaphragm and Intercostal Muscles: These muscles control breathing. The diaphragm contracts during inhalation, pulling air into the lungs, while it relaxes during exhalation. 

Breathing is the physical act of moving air in and out of the lungs, whereas respiration is the cellular process of producing energy from oxygen and glucose. 

Smoking: Negatively affects lung function, increases the risk of cancer, and can impair overall growth and development by reducing oxygen availability to tissues. 

1. Nicotine: 

• Effect: Highly addictive stimulant that increases heart rate, blood pressure, and the release of adrenaline. It can also lead to dependency and cravings. 

2. Tar: 

• Effect: A mixture of chemicals that accumulates in the lungs, leading to damage of lung tissue, irritation, and respiratory issues. 

3. Carbon Monoxide: 

• Effect: Reduces the ability of blood to carry oxygen by binding to haemoglobin, leading to shortness of breath and increased strain on the heart. 

 Invasive species: An organism that causes ecological or economic harm in a new environment where it is not native. They can disrupt food chains, cause native species extinction, and alter ecosystem functions. 

 Variety of Habitats: Different species thrive in unique environments within ecosystems, such as coral reefs in the ocean or grasslands on land. 

Bioaccumulation: The gradual build-up of toxic substances (e.g., heavy metals or pesticides) in organisms as they consume contaminated food or water. This can affect the health of the entire ecosystem, as toxins move up the food chain, often causing death or reproductive harm in higher-order predators

• Antagonistic muscles – A pair of muscles that work together in opposition; one muscle contracts while the other relaxes, enabling controlled movement, like the biceps and triceps. 

• Ecosystem – A system formed by the interaction of all living organisms (plants, animals, microorganisms) with their physical environment (soil, water, air), working together to sustain life.

• Joint – A structure in the body where two or more bones meet, allowing movement. Examples include the knee, elbow, and shoulder. 

• Ligament – A tough band of tissue that connects bones to other bones at joints, providing stability and support during movement. 

• Tendon – A fibrous tissue that connects muscle to bone, enabling muscles to move bones when they contract.

• Capillaries – The smallest blood vessels in the body that connect arteries to veins. They facilitate the exchange of oxygen, carbon dioxide, nutrients, and waste between the blood and tissues. 

• Kaitiakitanga – A Māori concept of guardianship or stewardship, emphasizing the responsibility to protect and care for the environment and natural resources, ensuring their sustainability for future generations. 

ATOMIC STRUCTURE:

Atomic Models 

Rutherford Model: It describes an atom as mostly empty space, with a tiny, dense, positively charged nucleus at the centre, where most of the mass is concentrated. Electrons move around the nucleus in orbits at a distance. 

The model came from Rutherford's gold foil experiment, which showed that most alpha particles passes through a thin sheet of gold but some were deflected, indicating the presence of a small, dense nucleus. 

Purity refers to how much of a specific substance is present in a mixture. A pure substance contains only one type of chemical, while impure substances have multiple components. Purity can affect properties such as melting point and boiling point. 

Not all reactions produce a single pure product. Impurities can form due to side reactions, contamination, or incomplete reactions. This results in a mixture of the desired product with other unwanted byproducts.  

• Sodium and potassium: Very reactive with water and oxygen, producing heat and hydrogen gas. React vigorously with acids. 

• Calcium and magnesium: React with water slowly (calcium more reactive) and react with acids to produce hydrogen gas. 

• Zinc and iron: React with dilute acids, releasing hydrogen gas. React slowly with oxygen at room temperature. 

• Copper, gold, and silver: Least reactive. These metals do not react with water or dilute acids and react slowly with oxygen (copper forms a green patina over time). 

• Endothermic reactions absorb energy from their surroundings, causing a drop in temperature (e.g., photosynthesis). 

• Exothermic reactions release energy, resulting in a temperature increase (e.g., combustion). These processes can be identified by changes in temperature during the reaction. 

The solubility of salts (how well a salt dissolves in water) varies with temperature. Typically, as temperature increases, the solubility of most salts increases. For example, more table salt (sodium chloride) can dissolve in hot water than in cold water. 

Inert substances are generally unreactive and do not easily participate in chemical reactions. Examples include noble gases (like helium, neon) and some metals like gold. They resist reacting because they have stable electron configurations. 

• Solubility – The ability of a substance to dissolve in a solvent. Solubility depends on factors such as temperature, pressure, and the nature of both the solute and solvent. 

• Galaxy – A massive system of stars, gases, dust, and dark matter bound together by gravity. Galaxies come in various shapes, including spiral, elliptical, and irregular, and can contain billions to trillions of stars. 

• Endothermic – A process that absorbs heat from its surroundings, usually causing the temperature of the surroundings to decrease. Endothermic reactions require energy input to proceed. 

• Purity – The measure of how free a substance is from impurities or contaminants. A pure substance consists of only one type of element or compound and has consistent properties throughout. 

• Climate – The long-term average weather patterns in a region, typically measured over periods of decades to centuries. It includes factors like temperature, humidity, wind, and precipitation. 

• Weather – The short-term conditions in the atmosphere at a specific time and place, including factors like temperature, humidity, wind, and precipitation. Weather can change from minute to minute, day to day. 

• Magnetic field – The invisible field around a magnet or a moving electric charge that exerts a force on other nearby magnets or magnetic materials. Magnetic fields are depicted by lines of force, which indicate the direction and strength of the field. 

• Inert – A substance that does not readily react chemically with other substances under normal conditions. Inert materials are often stable and unreactive. Examples include noble gases like helium and neon. 

 SPEED, MOTION & FORCES 

Contact / Non-contact Forces 

• Contact forces: friction, air / water resistance, thrust, support, reaction, buoyancy. 

• Non-contact forces include gravitational, magnetic, electrostatic. 

Resultant Force 

• The resultant force is all the forces in one force. 

• It is also the “overall force”. 

• Forces that act in one direction can be added together. 

• Forces that act in opposite direction must be taken away. 

• Forces that act vertically and horizontally cannot be added and taken away from each other and must be considered separately. 

Balanced Forces: When the forces acting on an object are equal and opposite, they cancel each other out. This results in no change in motion (the object remains at rest or continues to move at constant speed). 

Unbalanced Forces: If the forces acting on an object are not equal, this creates a net force, which causes the object to accelerate, decelerate, or change direction. 

Mass 

• Mass is the amount of matter an object has. 

• Units: gram (g), kilogram (kg), tonne (t) 

Weight 

• The amount of mass due to gravity 

• Units: newton (N) 

Speed  

• Speed is the rate at which an object covers distance. 

• Speed = Distance/Time 

• E.g. Speed = 100km/2hours = 50km/h 

• Average Speed: The total distance travelled divided by the total time taken. 

• Factors Affecting Speed: Influenced by forces like gravity, friction, or propulsion. 

• Examples: Running, driving, and cycling all involve speed, which can vary based on conditions like terrain or effort. 

In a distance/time graph: 

• A straight, sloped line indicates constant speed. 

• A horizontal line indicates the object is stationary (no movement). 

• The steeper the slope, the faster the speed. 

• Curves on the graph indicate acceleration (changing speed). You can draw a graph by plotting distance on the y-axis and time on the x-axis. 

Pressure: 

• Pressure is the force exerted per unit area. 

• Pressure = Force/Area 

• E.g. Pressure = 100N/5m^2 = 20N/m^2 

• Measured in pascals 

• Effect: The greater the force or smaller the area, the higher the pressure. 

• Applications: Found in many everyday contexts like tire pressure, air pressure, and water pressure. 

• Factors Affecting Pressure: Depends on the force exerted and the surface area over which it is distributed. 

Moment: 

• Moment is the turning effect of a force around a pivot. 

• Moment = Force x Distance from the Pivot 

• E.g. Moment = 10N x 2m = 20Nm 

• Effect: The further the force is applied from the pivot point, the greater the moment. 

• Applications: Seen in tools like wrenches, levers, and door handles. 

• Factors Affecting Moment: Influenced by the magnitude of the force and the distance from the pivot point where the force is applied. 

IMPORTANT FORMULAS 

1. Speed: 

     - V = d ÷ t 

     - (Speed = distance ÷ time) 

2. Moment  

     - M = F × r 

     - (Moment= force × distance from pivot) 

3. Contact Pressure 

     - P = F ÷ A 

     - (Pressure = force ÷ area) 

LIGHT AND COLOR: 

Light is a form of energy that travels in waves and consists of tiny particles called photons. It moves extremely fast about 299,792 kilometres per second. The part of light we can see is called the visible spectrum, which includes all the colours of the rainbow. Light can bounce off surfaces, bend when passing through materials, or be absorbed.  

DISPERSION:  

White light is a mixture of all colours (red, orange, yellow, green, blue, indigo, violet). When passed through a prism, the light disperses into these colours because each colour travels at a different speed in the glass. 

REFRACTION: 

Refraction occurs when light passes from one medium to another (e.g., from air to glass or water), causing a change in speed and direction. Light bends toward the normal when it slows down (air to glass) and away from the normal when it speeds up (glass to air).