G9 Semester 2 Exam 2025

Alfred Wegener

A German scientist who proposed the theory of continental drift

Harry Hess

A naval scientist who proposed the theory of sea-floor spreading

evidence for Alfred Wegener's theory of continental drift

Fossil Evidence, Fit of the Continents

evidence for Harry Hess' theory of seafloor spreading

Magnetic Striping, Age of Seafloor, Sediment Thickness

magnetic striping

The pattern of alternating normal and reversed magnetic polarities found in the seafloor on either side of the spreading center.

Magnetite

magnetic material found in the seafloor

continental crust

crust that lies beneath the Earth's continents and is about 25-70 km thick. Less dense.

oceanic crust

crust that lies beneath the ocean and is usually 7-10 km thick. More dense.

convergent boundary

A plate boundary where two plates move toward each other.

oceanic trench

Deep, narrow trough in the ocean floor where subduction is taking place.

Subduction

The process by which one plate is pushed underneath another plate at a convergent boundary

volcanic island arc

a series of volcanoes formed at a subduction zone at a oceanic-oceanic convergent boundary.

divergent boundary

A plate boundary where two plates move away from each other.

Rifting

the process by which Earth's crust breaks apart; can occur within continental crust or oceanic crust

mid-ocean ridge

An underwater mountain chain where new ocean floor is formed

transform boundary

A plate boundary where two plates move past each other in opposite directions

fault line

a crack in Earth's surface caused by moving plates

Mantle

The layer of hot, solid material between Earth's crust and core.

Magma

A molten mixture of rock-forming substances, gases, and water from the mantle

slab pull

the pulling of a tectonic plate as its edge subducts deep into the mantle

ridge push

when the force of gravity moves a plate downward and away from a ridge

Volcanoes

an opening in the Earth's crust through which molten lava, ash, and gases are ejected.

Ring of Fire

A zone of intense volcanic activity a the boundary between the Pacific plate and surrounding continental plates

Focus

The point beneath Earth's surface where rock breaks under stress and causes an earthquake

Epicentre

the point on the Earth's surface directly above the focus of an earthquake

Seismometer

Instrument used to measure horizontal or vertical motion during an earthquake.

P (primary) waves

longitudinal waves (back and forth) that travel fast.

S (secondary) waves

transverse waves (up and down) travel slower than P-waves.

surface waves

seismic waves that travel along the Earth's surface. Causes the most destruction.

earthquake

The shaking that results from the movement of rock beneath Earth's surface.

Richter scale

A scale that rates an earthquake's magnitude based on the size of its seismic waves.

tectonic plates

Sections of the Earth's crust that move due to convection currents.

plate boundary

the region where two tectonic plates are in contact

Hot spot

A hot spot is an localized area where magma from deep in the mantle rises, not necessarily associated with a plate boundary

Proton

A subatomic particle that has a positive charge, a relative weight of 1, and found in the nucleus of an atom

Neutron

A subatomic particle that has no charge, relative weight of 1, and found in the nucleus of an atom

Electron

A subatomic particle that has a negative charge, no weight and orbits the nucleus

atomic number

the number of protons in the nucleus of an atom

mass number

the total number of protons and neutrons in the nucleus of an atom

Isotopes

Atoms of the same element (same no. of protons) that have different numbers of neutrons

electronic configuration

The arrangement of electrons in shells around the nucleus of an atom, e.g. sodium = 2, 8, 1

electron shells

paths electrons travel to orbit the nucleus; each can hold a max no. of electrons: 2, 8, 8, 18

Valence electrons

Electrons on the outermost shell of an atom

Cation

A positively charged ion

Anion

A negatively charged ion

ionic bonding

Chemical bonding that involves the transfer of electrons, resulting in attraction between cations and anions

covalent bonding

Chemical bonding resulting from the sharing of electron pairs between two non-metal atoms

metallic bonding

Chemical bonding that results from the attraction between metal atoms and the surrounding sea of delocalised electrons

chemical formula

shows the elements in the compound and the ratio of atoms

Group

A vertical column on the periodic table

Period

Horizontal rows on the periodic table

alkali metals

Group 1 elements except for hydrogen, they are highly reactive

Alkali Earth Metals

Group 2 elements, reactive

Halogens

Group 7 elements, highly reactive

Noble gases

Group 8 elements, not reactive

delocalized

the spreading of electrons over multiple atoms in a molecule or solid, rather than being confined to a single atom or a specific bond between two atoms

flame test

analytical chemistry test used to identify the presence of specific metal cations based on the characteristic color they produce when heated in a flame

hydroxide test

analytical chemistry test that uses sodium hydroxide to identify specific metal cations in an aqueous solution based on the color of the precipitates formed

carbonate test

analytical chemistry test used to identify the presence of the carbonate anion by reacting sample with acid to produce bubbles of carbon dioxide gas

Central Nervous System (CNS)

brain and spinal cord

Peripheral Nervous System (PNS)

the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.

Neurons

specialized nerve cells that transmit electrical signals called nerve impulses around your body

Dendrites

Branchlike parts of a neuron that are specialized to receive information.

Axon

A threadlike extension of a neuron that carries nerve impulses away from the cell body.

Axon terminal

The endpoint of a neuron where neurotransmitters are stored

Schwann cells

Fatty cells responsible for the formation of myelin.

myelin sheath

A fatty layer made up of schwann cells that insulates some axons to allow for faster movement of electrical impulses along the axon

sensory neurons

neurons that receive information from the external world and convey this information to the CNS

relay neurons

These connect the sensory neurons to the motor or other relay neurons. They have short dendrites and short axons.

motor neurons

neurons that carry outgoing information from the CNS to the muscles and glands

Synapse

Gap between axon terminal of one neuron and the dendrites of the next neuron

Neurotransmitters

chemical messengers that diffuse across the synaptic gaps between neurons

Cerebrum

Largest part of the brain; responsible for voluntary movement, processing sensory information, and complex thought.

Cerebellum

Balance and coordination

Brainstem / Medulla

responsible for automatic survival functions e.g. breathing, heart rate, blood pressure

frontal lobe

A region of the cerebral cortex that controls movement, higher order thinking, problem solving and emotion

parietal lobe

A region of the cerebral cortex that receives sensory input for touch and body position

temporal lobe

A region of the cerebral cortex responsible for hearing and language.

occipital lobe

A region of the cerebral cortex that processes visual information

stimulus response model

Stimulus - receptor - sensory neuron - control centre - motor neuron - effector - response

Receptor

special organs or cells that can respond to stimuli and transmit signal to sensory neuron.

photoreceptor - light

chemoreceptor - smell

thermoreceptor - temperature

mechanoreceptor - touch

pain receptor - pain / damaged cells

reflex arc

A neural pathway that shortcuts through the spinal cord, resulting in rapid, involuntary action

Metabolism

the chemical processes that occur within a living organism in order to maintain life. catabolic = reactions that break down. anabolic = reactions that build.

cellular respiration

glucose + oxygen --> carbon dioxide + water + energy

Enzymes

Proteins that speed up chemical reactions. Are not used up during reactions.

Homeostasis

process by which organisms maintain a relatively stable internal environment

endocrine system

Consists of glands that produce hormones to regulate the body's internal environment

hormones

chemical messengers that travel through the bloodstream, and affect target cells

Hypothalamus

brain region in charge of homeostasis, controls the pituitary gland

pituitary gland

The endocrine system's "master" gland. Controls other endocrine glands.

thyroid gland

produces the hormone thyroxine which increases metabolic heat.

vasoconstriction and vasodilation

narrowing and widening of blood vessels

Sensation vs. Perception

Sensation is arrival of info to brain, perception is interpretation of info in brain

sensory memory

A type of storage that holds sensory information for a few seconds or less.

short-term memory

"working" memory that holds a few items briefly, e.g. seven digits of a phone number while dialing

long-term memory

the relatively permanent storage of information

Rehearsal

the conscious repetition of information, either to maintain it in short-term memory (maintenance) or to encode it for long-term storage (elaborate)

Retrieval

the process of getting information out of long-term memory

Chunking

organizing information into familiar, manageable units; helps improve memory

Contextual Clues

improves memory by situating information in familiar contexts