Podar International School Periodic Test 3 (2025-26) Science Review

A comprehensive set of vocabulary-style flashcards covering Biology, Chemistry, and Physics concepts from the Std. IX Periodic Test 3 transcript.

Unicellular organisms

A group of organisms consisting of a single cell, including examples such as Chlamydomonas, Paramoecium, Amoeba, and bacteria.

Ribosomes

The only cell organelle typically seen in a prokaryotic cell; they are also responsible for producing proteins in the presence of the endoplasmic reticulum.

Golgi apparatus

The cell organelle involved in forming complex sugars from simple sugars.

Columnar epithelium

A type of epithelial cell responsible for the absorption of digested food materials in the intestine.

Cardiac muscle tissue

Cylindrical, branched, and uninucleate muscles that make up the walls of the heart and contract rhythmically throughout life without fatigue.

Meristematic tissues

Plant tissues that are localized and consist of actively dividing cells.

Hybridisation

A method used to develop crop varieties with useful characters by crossing genetically dissimilar plants to combine desirable traits.

Viruses

Entities that lack cellular membranes and cell organelles, and do not show characteristics of life until they enter a living body.

Chloroplast

A type of plastid in plant cells that has a specific structure used for photosynthesis.

Sclerenchyma

A plant tissue containing dead, thick-walled cells where the walls are thickened by a chemical such as lignin.

Differentiation

The process in plant cells that leads to the development of permanent tissues with specific roles.

Apical meristem

Meristematic tissue located at the growing tips of stems and roots.

Intercalary meristem

Meristematic tissue located at the base of leaves or internodes on twigs.

Lateral meristem

Meristematic tissue responsible for increasing the girth of the stem or root.

Boiling point of acetone in Celsius

The temperature of $56^\text{o}C$, which corresponds to $329{,}K$ on the Kelvin scale.

Hydrogen sulphide gas

A gas produced by reacting iron filings and sulphur powder mixture with dilute hydrochloric acid, identified by its strong rotten egg smell.

Metalloid

An element that has properties intermediate between those of metals and non-metals, such as Germanium.

Co

The chemical symbol for the element Cobalt.

Ozone

A triatomic molecule formed from three oxygen atoms ($O_3$).

Tyndall effect

The scattering of a beam of light by medium particles, typically observed in colloidal mixtures.

Suspension

A heterogeneous mixture in which solute particles do not dissolve but remain suspended and eventually settle down when left undisturbed.

Magnesium chloride formula

The chemical formula $MgCl_2$, with a molecular mass of $95{,}u$ based on $Mg = 24{,}u$ and $Cl = 35.5{,}u$.

Law of Conservation of Mass

The chemical law stating that the total mass of reactants before a reaction is equal to the total mass of products after the reaction.

Diffussion

The process where a substance with no definite shape or volume moves and spreads easily at room temperature.

Newton’s First Law of Motion

The principle stating that an object at rest remains at rest unless acted upon by an external force, also known as the law of inertia.

Average speed

The total distance covered divided by the total time taken; for example, a car covering $80{,}km$ in $2{,}h$ and $100{,}km$ in $4{,}h$ has an average speed of $30{,}km/h$.

Pressure

The force or thrust exerted per unit area, calculated using the formula $P = \frac{\text{Thrust}}{\text{Area}}$.

Acceleration due to gravity ($g$)

The acceleration experienced by an object in free fall, which is maximum at the poles and minimum at the equator.

Uniform motion

Motion where an object covers equal distances in equal intervals of time.