IGCSE extended combined science (mod 2?-4) ADD ONE

Acceleration

An increase in speed (usually written as m/s²)

acceleration = change in velocity/time taken

A=Δv/Δt

Acceleration equation

Mass

How much matter an object has. Constant throughout the universe and measured in kg

Weight

The (downward) force of gravity that acts on an object because of its mass. Dependant on gravitational field strength and measured in Newtons (N)

Mass x 9.8N = Weight on Earth

How to find the weight of objects on earth

W= MG

The equation for weight

1.6N/kg

Approximate gravitational field strength of the moon

Acceleration of free fall

The acceleration of any object falling freely under gravity (usually to a massive object)

Force= mass x acceleration

The force equation

Centre of mass

The single point at which the weight of an object (the force due to gravity) is considered to act

Tensile forces

Forces that stretch a material

Compressive forces

Forces that compress a material

Bending forces

Forces that bend a material

Torsional forces

Forces that twist a material

Pressure = force/area

P= F/A

pressure equation

Friction

The force between two surfaces (may impede motion and/or produce heat)

Pressure

The force acting per unit area at right angles to a surface measured in Pa (1Pa = 1N/m²)

Air resistance

Friction acting on an object moving through air (also called drag when moving through another substance)

Resultant force

A single force that has the same effect on a body as two or more forces

Force equation

F=ma

Balanced forces

When two (or more) forces are equal and an object’s speed does not change. (Can be stationary or constant movement)

Joule

The SI unit for energy

Kinetic energy

The energy store of a moving object (movement)

Gravitational potential energy

The energy store of an object raised up against the force of gravity (high up energy)

Chemical energy

stored in bonds between atoms and released when chemical reactions take place

Elastic (strain) energy

Energy stored in the changed shape of an object (stretched or disformed)

Nuclear energy

Energy stored in the nucleus of an energy (fission/fusion)

Electrostatic energy

Energy stored when electrical charges are separated or squashed/forced together

Thermal (internal) energy

Energy of an object: the total kinetic AND potential energies of its participles (heat)

Doing work

Transferring energy by means of a force

Principle of conservation of energy

Energy cannot be created or destroyed, only stored or transferred

Efficiency

The fraction/percentage of energy supplied that is usefully distributed/transferred to complete the wanted action

Efficiency equation

Efficiency= useful energy output/total energy input

Gravitational potential energy equation

ΔE^p=mgΔh

Kinetic energy equation

E^k= ½ mv²

Non renewable

An energy source that is gone forever once it has been used

Renewable

An energy resource that will be replenished naturally when used

Nuclear fission

The process in which a large nucleus from radioactive material is split into two smaller nuclei and energy is released

Nuclear fusion

The process in which two small light nuclei join together to form a new heavier nucleus and produce energy

Work done

The amount of energy transferred when one thing exerts a force onto another; the energy transferred by a force when it moves from one store to another.

W = fd = ΔE

The mechanical work done (by a force) equation

Joules (J)

SI unit of energy transferred/work done

Work done

Force x distance moved in the direction of the force

P=W/t

Power equation

p= ΔE/t

Power equation

Watt (W)

The SI unit for power

Alimentary canal

The long tube running from mouth to anus that is part of the digestive system

Ingestion

The taking of food and drink into the body. In humans, using the lips, teeth and tongue

Absorption

Soaking up nutrients from the alimentary canal into the blood through the walls of the small intestine (semipermeable membrane)

Digestion

Breaking down large pieces/molecules of food into smaller pieces/molecules so they can be absorbed into the body

Assimilation

The intake of nutrients as it becomes part of the body and is used by individual cells for energy and/or to make new substances

Egestion

The process of the removal of unnecessary material from the body (in humans, usually as faeces)

Goblet cells

Cells found in the lining of respiratory passages and digestive system which secrete mucus

Lumen

The space in the centre of a tube (in a body, usually) through which substances can move

Duodenum

The first part of the small intestine into which the pancreatic and bile ducts empty fluids for chemical digestion

Ileum

The second part of the small intestine in which most absorption (of digestive nutrients and water) takes place

Amylase

The enzyme secreted by the pancreas and salivary glands that breaks down starch

Protease

The enzyme secreted by the pancreas and walls of the stomach that breaks down protein

Lipase

The enzyme secreted by the pancreas that breaks down fats and oils

Gallbladder

The small organ that stores bile that the liver makes until it needs to be released into the duodenum

Liver

The organ that produces bile and regulates the concentration of blood glucose

Pancreas

The organ that secrets pancreatic juice (which helps with chemical digestion) and secretes insulin and glucagon

Alimentary canal

Part of the digestive system: a long tube that runs from mouth to anus

Stomata

Openings in the surface of a leaf surrounded by pairs of guard cells which control whether they are open or closed. Used for carbon dioxide to diffuse into a plant

Xylem

A plant tissue made from dead and empty cells joined end to end that transports water and mineral ions throughout the plant. Also helps to support the structure of the plant

Phloem

A plant tissue made from living cells joined end to end that transports substances the plant makes for itself. For example, sucrose and amino acids

Arranged in a ring near the outside edge

Vascular bundle position in a stem

In the centre

Vascular bundle position in a root

Support and hold them out flat

Vascular bundle task in leaves

Transpiration

The loss of water vapour from leaves that lives water from roots to the rest of the plant

Spongy Mesophyll

The layer of cells immediately beneath the palisade mesophyll, where some photosynthesis happens; this tissue contains a lot of air spaces between the cells

Humidity

How much water vapour is present in the air

Wilting

When a plant loses more water than it can take up/in therefore cells lose their turgidity

Circulatory system

A system of blood vessels with a pump and valves to ensure a one way flow of blood

Oxygenated blood

Blood containing a lot of oxygen

Deoxygenated blood

Blood containing little oxygen

Double circulatory system

A system in which blood passes through the heart twice in one complete circuit of the body (not time lord)

Atria (sg, atrium)

The thin walled chambers at the top of the heart which receive blood

Ventricles

The thick walled chambers at the base of the heart which pump out blood

Septum

The structure that separates the left and right side of the heart

Valves

Structures that allow a liquid to only flow in one direction

coronary arteries

Vessels that deliver oxygenated blood to the heart muscle

left side of the heart

Pumps oxygenated blood to the body

Right side of the heart

Pumps deoxygenated blood to the lungs

Coronary heart disease (CHD)

Disease caused by blockage of the coronary arteries

Pulse rate

The number of times an artery expands and recoils in one minute. Also a measure of heart rate

Plasma

The liquid in which blood cells are suspended

Red blood cells

Biconcave blood cells containing haemoglobin with no nucleus which transport oxygen

White blood cells

Blood cells with a nucleus which help to defend against pathogens

Platelets

Tiny cell fragments in blood which help with clotting

Haemoglobin

Red pigment in red blood cells which can combine reversibly with oxygen. Also a protein

Phagocytosis

Taking bacteria or other small structures into a cell’s cytoplasm and digesting them with enzymes

Phagocytes

White blood cells that destroy pathogens via phagocytosis

Gas exchange

The diffusion of oxygen and carbon dioxide into and out of an organisms body

Gas exchange surface

A part of the body where gas exchange between the body and the environment takes place

Thorax

The chest; the part of the body from the neck to the diaphragm

Bronchus

One of the two tubes that takes air from ghe trachea into the lungs

Bronchiole

A small tube that takes air from a bronchus to every part of the lungs