Science exam 2026

Central Nervous System (CNS)

The major division of the nervous system consisting of the brain and spinal cord.

Peripheral Nervous System (PNS)

The division of the nervous system made up of nerves that connect the brain and spinal cord with other parts of the body.

Brain

The body's control centre, responsible for intelligence, creativity, perceptions, conscious reactions, emotions, memories, and regulating all body functions.

Meninges

The three protective membranes (dura mater, arachnoid, and pia mater) located beneath the skull that surround and protect the brain.

Cerebrum

The largest part of the brain, responsible for thinking, memory, decision making, speech, and conscious actions including seeing and hearing.

Cerebellum

The brain region that controls balance, coordinates complex movements, maintains posture, and supports motor learning and precision.

Brainstem

The structure connecting the brain to the spinal cord that regulates sleep controls basic life functions and involuntary actions such as breathing, heartbeat, and swallowing,

Frontal Lobe

The cerebral lobe involved in thinking, reasoning, problem solving, planning, decision making, personality, behavior, movement control, and speech production.

Parietal Lobe

The cerebral lobe responsible for perceiving touch, pressure, temperature, and pain, as well as understanding spatial relationships and combining sensory information.

Occipital Lobe

The cerebral lobe responsible for processing and interpreting visual information.

Temporal Lobe

The cerebral lobe responsible for hearing, language comprehension, memory, learning, and emotions.

Corpus Callosum

A bridge of 100 million nerve fibres connecting the left and right cerebral hemispheres.

Thalamus

A forebrain structure that controls sensory integration and motor integration.

Hypothalamus

A forebrain structure that controls body temperature, emotions, hunger, thirst, appetite, digestion, sleep and acts as the bridge between the nervous and endocrine system.

Pituitary Gland

A gland in the brain that controls hormones and assists in turning food into energy.

Pons

A hindbrain structure that assists in transferring messages between various parts of the brain and the spinal cord.

Medulla

A hindbrain structure in the brainstem controlling unconscious or involuntary actions such as breathing, heart rate, and digestion.

Forebrain

The major division of the brain consisting of the cerebrum, thalamus, and hypothalamus.

Hindbrain

The major division of the brain consisting of the cerebellum, pons, and medulla.

Receptors

Specialised groups of cells located in sense organs that detect changes in the environment (stimuli) and convert them into electrical impulses.

Photoreceptor

The type of receptor cell (rods and cones in the retina of the eye) that detects light stimuli.

Mechanoreceptor

A type of receptor that detects mechanical stimuli such as sound (hairs in the cochlea of the ear) or movement and pressure in the skin.

Thermoreceptor

A type of receptor located in the skin that responds to temperature stimuli, including heat and cold.

Chemoreceptor

A type of receptor sensitive to chemical stimuli, such as tastebuds on the tongue and olfactory nerves inside the nose.

Neuron

An electrically excitable nerve cell that processes and transmits information throughout the body via electrochemical signals (impulses).

Dendrites

Branched projections of a neuron that receive incoming impulses from other neurons and conduct them towards the cell body.

Axon

The long, slender projection of a neuron that extends from the cell body to carry impulses away toward other cells.

Myelin Sheath

A fatty substance wrapped around the axon of neurons that insulates them and speeds the transmission of nerve impulses.

Axon Terminal

The end of a neuron where axons form synaptic contacts with other nerve cells or with effector cells (muscles or glands).

Sensory Neuron (Afferent Neuron)

A neuron that conducts signals and transmits information received from sensory receptors to the central nervous system.

Interneuron (Association Neuron)

A neuron located in the central nervous system (brain and spinal cord) that connects sensory and motor neurons allowing communication.

Motor Neuron (Efferent Neuron)

A neuron that sends signals away from the central nervous system to an effector such as a muscle or gland.

Effector

Any part of the body, such as a muscle contracting or a gland secreting a hormone, that elicits or produces a response.

Action Potential

The electrical message or impulse transmitted along a neuron from the dendrites to the axon terminal.

Synapse

The tiny physical gap where two neurons meet, across which chemical signals are transmitted.

Neurotransmitters

Chemicals released into the synaptic gap by one neuron that diffuse across to activate receptors on the next neuron.

Reflex Arc

A rapid, involuntary neural pathway where the brain is bypassed and signals travel via an interneuron in the spinal cord to directly stimulate an effector. e.g pulling your hand away from something hot

How the Endocrine and Nervous systems work together

homeostasis

The self-regulating biological process that allows living organisms to keep their internal environment stable and balanced, even when conditions outside change

Stimulus response model

Stimulus – Receptors – Coordination centre – Effectors – Response

Hormones

A chemical that moves throughout the body by binding to specific receptors found on target cells bringing about a change in that organ/tissue which regulates behaviour and emotions

Endocrine system

A network of glands and organs that create and release hormones directly into your bloodstream to coordinate and regulate essential bodily functions.

How the endocrine and nervous system work together for body regulation

The nervous system detects changes and sends fast electrical signals, while the endocrine system releases hormones to create longer-lasting responses. Together, they maintain homeostasis by regulating body temperature, blood glucose and other internal conditions.

Non-infectious diesease

Is not contagious and cannot be spread from one person to another. e.g diabetes, cancer

Active immunity

The process of your immune system producing antibodies and specialized white blood cells in response to a foreign substance or pathogen

Herd immunity

happens when a large part of a population becomes immune to a contagious disease making the spread of the pathogen from person to person rare or unlikely.

3rd line of defence

Uses lymphocytes to remember pathogens. B lymphocytes detect antigens on the pathogen and divide to create plasma cells which produce antibodies, trapping and destroying the pathogen.

2nd line of defence

A reaction to the infection using phagocytosis which sends white blood cells to destroy pathogens resulting in inflammation.

Pathogen

Any biological agent that causes disease in a host, such as an animal, human or plant. Once in a host, they evade immune responses and use the body’s resources to replicate and cause illness.

Non Cellular pathogens

Disease-causing agents that lack a cellular structure, have no independent metabolism, and cannot reproduce on their own. They include prions which are abnormal and infectious proteins and viruses which contain genetic material.

Infectious disease

Contagious and spread by both cellular and non-cellular pathogens. e.g covid

How are diseases transmitted?

By either direct or indirect transmissions. Indirect transmission may include contaminated objects or vectors whilst direct transmission includes coughing, sneezing and physical contact

Methods to reduce transmission of disease

Quarantine laws, personal hygiene, animal and pest control, clean water supply, vaccination , and treatment

Cellular pathogens

Living microorganisms composed of cells that can reproduce and grow independently. They Include bacteria,rthropods and worms, protozoans and fungi.

1st line of defence

Physical barriers such as intact skin, cilia, mucus and nasal hairs that aim to block pathogens from entering the body.

Passive immunity

The transfer of ready-made antibodies into a person's body from an external source.

Vaccinations

The process of injecting an inactive piece of pathogen into the body so the immune system can recognise the antigen creating memory B and T cells.

Structure of the atom

Positively charged protons and neutrally charged neutrons found in the atoms nucleus in addition to negatively charged electrons that orbit the nucleus in layers called shells.

Atomic Number

The smaller number shown on an element in the periodic table determined by the number of protons in the nucleus of an atom.

Mass number

The largest number shown on an element in the periodic table determined by the sum of protons and neutrons in the nucleus.

Isotopes

Atoms of the same element but with more or less neutrons e.g Carbon-13

Stable isotope

An atom with a full outermost (valence) electron shell

Unstable isotope

An atom with an unfull outermost (valence) electron shell

Ion

An atom with an unequal amount of protons and neutrons

Cation

A positively charged atom formed by the loss of an electron

Anion

A negatively charged ion formed by the gain of an electron.

Groups

The columns on a periodic table which tells you the number of valence electrons

Half-life

How quickly half of the unstable radioactive atom decays

Radioactive decay

Radioisotopes give off radiation as they decay to a stable form (alpha, beta, gamma)

Alpha Particles

Weak helium nuclei that travels at 5% of the speed of light and can be stopped by paper

Beta Particles

Particles produced when neutrons change into protons or electrons that can be stopped by millimetres of aluminium

Gamma Particles

Most dangerous form of radiation that is a particle of light traveling at the speed of light and can only be stopped by centimetres of lead

Periods

The rows on the periodic table telling you the number of shells in the atom

Reactants

The original substances in a chemical reaction

Products

The substances formed in a chemical reaction

Equations

A statement describing a chemical reaction, with the reactants on left and products on right separated by an arrow.

States in an equation

(g)= the entity is in a gaseous state, (l)= the entity is in a liquid state, (s) = the entity is in a solid state

Conservation of mass

The total mass of reactants is the same as the total mass of products in an equation as mass cannot be created nor destroyed

law of constant proportions

A given chemical compound always contains its constituent elements in a fixed ratio by mass.

Acids

Substances that release Hydrogen ions (H+) into an aqueous solution

Bases

A substance that produces Hydroxide ions (OH-) into a solution

Ph scale

A scale running from 0-14 used to measure the acidity/alkalinity of a solution. The closer to 0 the more acidic, the closer to 14 the more alkaline and anything with a Ph of 7 is neutral.

Indicators

Chemicals that change colour in the presence of an acid or base.

Challenges that cause food insecurity

Climate change, flooding, droughts, poverty, global conflict

Impacts of food insecurity

Increased disease, economic decline, poverty, starvation

Solutions to ensure food security

Sustainable farming, aquaponics, hydroponics, vertical farming, desalination plants

element

A pure substance that cannot be broken down into simpler substances by ordinary chemical processes

Radioisotope

Unstable forms of chemical elements that naturally or artificially emit radiation