Grade 9 Science and Social Science Vocabulary Review

Comprehensive vocabulary flashcards covering key concepts from Physics (Laws of Motion), Chemistry (Atomic Foundations of Matter), Biology (Plant and Animal Tissues), History (Ancient State and Society), and Geography (Atmosphere and Climate).

Newton's First Law of Motion

A fundamental physical law stating that an object at rest remains at rest, and an object in motion continues to move with a constant velocity, unless a net force acts upon it.

Inertia

The inherent tendency of objects to resist any change in their state of rest or uniform motion.

Newton's Second Law of Motion

A law stating that when a net force acts on an object, the object accelerates in the direction of the net force; the magnitude of acceleration is proportional to the net force and inversely proportional to the mass ($F = ma$).

Newton's Third Law of Motion

A law stating that whenever one object exerts a force on a second object, the second object simultaneously exerts an equal and opposite force on the first object.

Newton (unit)

The SI unit of force, symbolised as $N$, defined as the force that produces an acceleration of $1\,m\,s^{-2}$ on an object of mass $1\,kg$ ($1\,N = 1\,kg\,m\,s^{-2}$).

Balanced Forces

Forces acting on an object that are equal in magnitude and opposite in direction, resulting in a net force of zero and no change in the object's state of motion.

Unbalanced Forces

Forces acting on an object whose vector sum (net force) is non-zero, resulting in acceleration or a change in velocity.

Force of Friction

A resistive force arising between surfaces in contact that acts in a direction opposite to the direction of motion or applied force.

Law of Conservation of Mass

A chemical law proposed by Antoine Lavoisier in 1789 stating that matter can neither be created nor destroyed in a chemical reaction.

Law of Constant Proportions

A law proposed by Joseph Proust stating that in any chemical compound, the constituent elements are always combined in a fixed ratio by mass regardless of its source.

Dalton's Atomic Theory

A scientific theory proposed by John Dalton in 1808 postulating that matter consists of indivisible particles called atoms that participate in chemical reactions without being created or destroyed.

Covalent Bond

A chemical bond formed between two atoms through the sharing of one or more pairs of valence electrons.

Ionic Bond

A chemical bond formed by the electrostatic force of attraction between oppositely charged ions produced by the transfer of electrons.

Cation

A positively charged ion formed when an atom loses one or more of its valence electrons.

Anion

A negatively charged ion formed when an atom gains one or more valence electrons.

Molecular Mass

The total mass of a covalent molecule, calculated by summing the atomic masses of all constituent atoms in its chemical formula.

Formula Unit Mass

The sum of the atomic masses of all atoms present in the formula unit of an ionic compound.

Meristematic Tissue

Plant tissue consisting of small, thin-walled, actively dividing cells with dense cytoplasm and prominent nuclei responsible for plant growth.

Apical Meristem

Meristematic tissue located at the tips of roots and shoots responsible for increasing the length of the plant.

Lateral Meristem

Meristematic tissue arranged along the circumference of stems and roots that increases plant girth.

Intercalary Meristem

Meristematic tissue located at the base of internodes or nodes that allows plants such as grasses to regenerate after cutting or grazing.

Differentiation

The process by which unspecialized meristematic cells undergo structural and functional changes to become specialized permanent tissue cells.

Parenchyma

A simple permanent plant tissue composed of living, thin-walled, loosely packed cells that store food, perform photosynthesis, or provide buoyancy.

Collenchyma

A simple permanent plant tissue consisting of living cells with unevenly thickened corners due to pectin deposition, providing flexibility and mechanical support.

Sclerenchyma

A simple permanent plant tissue composed of dead cells with thick, lignified walls that make plant parts hard and rigid.

Xylem

A complex permanent plant tissue composed of tracheids, vessels, xylem parenchyma, and xylem fibres that conducts water and minerals upward from roots.

Phloem

A complex permanent plant tissue consisting of sieve tubes, companion cells, phloem parenchyma, and phloem fibres that transports food from leaves to other plant parts.

Epithelial Tissue

Animal tissue composed of closely packed cells forming a protective outer layer on the body or lining internal body cavities and organs.

Connective Tissue

Animal tissue consisting of cells embedded in an extracellular matrix that connects, binds, and supports various body organs and structures.

Neuron

A specialized nerve cell of nervous tissue consisting of a cell body, dendrites, and an axon, designed to receive, process, and transmit electrical impulses.

Jana

An early Vedic social clan or group of people bound together primarily by kinship ties.

Janapada

A territorial political unit in ancient India that developed as kinship-based janas settled permanently in specific geographical regions.

Mahājanapada

Large, territory-based political units or kingdoms that emerged in ancient India around $600\,\text{BCE}$.

Sabhā

A smaller assembly in early Vedic polity composed of select elites that primarily performed judicial and advisory functions.

Samiti

A large representative assembly during the Vedic period representing the broader population and focusing on policy decisions and political affairs.

Śhreṇī

Collective associations or guilds of merchants, artisans, and craftspersons in ancient India that regulated product quality, set prices, and served as banking institutions.

Brahmadeya

Tax-free land grants gifted to Brahmins or individual villages by ancient Indian rulers.

Troposphere

The lowest layer of the atmosphere (average height $12\,km$) where air density is highest, temperature decreases with altitude, and almost all weather phenomena occur.

Stratosphere

The atmospheric layer extending up to $50\,km$ above Earth, free of clouds and weather disturbances, containing the protective ozone layer.

Mesosphere

The third layer of the atmosphere extending up to $80\,km$, where temperature decreases with altitude and most meteorites burn up upon entry.

Thermosphere

The atmospheric layer extending from $80\,km$ to $700\,km$ where temperature increases rapidly with altitude due to absorption of short-wave solar radiation.

Insolation

The incoming solar radiation intercepted by the Earth, decreasing in intensity from the equator toward the poles.

Monsoon

A seasonal wind system characterized by a periodic reversal in wind direction over the course of a year.

Carbon Footprint

The total amount of greenhouse gases released into the atmosphere as a result of human activities such as transportation, energy use, and production.