Everyday Science
Explore 28 authentic past paper questions categorized by topic.
Which vitamin is produced in the human body by sunlight?
Explanation: Vitamin D is synthesized in the skin when it is exposed to ultraviolet B (UVB) rays from sunlight.
The joint of the elbow is an example of which type of joint?
Explanation: The elbow joint is a classic example of a hinge joint, which allows movement in only one plane (flexion and extension), similar to the hinge of a door.
What is the primary cause of Type 2 diabetes?
Explanation: Type 2 diabetes is primarily caused by insulin resistance, where the body's cells fail to respond effectively to insulin, leading to elevated blood glucose levels over time.
What meteorological phenomenon occurs when rainfall exceeds 100 mm in a single hour?
Explanation: A cloudburst is an extreme and sudden rainfall event, typically defined as precipitation exceeding 100 mm per hour over a localized area, often causing flash floods.
What is the major component of natural gas?
Explanation: Natural gas is predominantly composed of methane (CH4), typically comprising 70–90% of its volume, making it the primary hydrocarbon in natural gas used for fuel.
SiO2 is the chemical formula for which common substance?
Explanation: SiO2, or silicon dioxide, is the primary component of sand and quartz. It is one of the most abundant compounds in the Earth's crust.
What is the chemical formula of Quartz?
Explanation: Quartz has the chemical formula SiO2 (silicon dioxide). It is one of the most abundant minerals in Earth's crust and is a key component of sand, granite, and many other rocks.
Which is the purest and highest quality form of coal?
Explanation: Anthracite is the purest and highest quality form of coal, containing 86–98% carbon and having the highest energy density. Lignite (brown coal) is the lowest quality with the least carbon content.
Two water molecules are bonded to each other by which type of bond?
Explanation: Water molecules are bonded to each other through hydrogen bonds — a relatively weak electrostatic attraction between the positively charged hydrogen of one molecule and the negatively charged oxygen of another.
What is the internationally used unit of sound intensity level?
Explanation: The decibel (dB) is the internationally standard unit used to measure sound intensity level. It is a logarithmic unit that expresses the ratio of a sound's intensity relative to a reference level.
Which material is primarily used in constructing greenhouses to produce the greenhouse effect?
Explanation: Glass is primarily used in greenhouses because it allows sunlight (short-wave radiation) to enter but traps the infrared radiation (heat) emitted by the interior, creating a warm environment for plants.
What percentage of forest cover is ideally required for environmental stability of a country?
Explanation: According to international environmental standards and Pakistan's own environmental policy, a minimum of 33% forest cover is required for a country to maintain ecological balance and environmental stability.
Carbon fixation during photosynthesis takes place in which part of the chloroplast?
Explanation: Carbon fixation occurs in the stroma of the chloroplast during the Calvin Cycle (light-independent reactions), where CO2 is converted into glucose using ATP and NADPH produced in the light reactions.
Photochemical smog does NOT contain which of the following components?
Explanation: Photochemical smog primarily consists of ozone, aldehydes, peroxyacetyl nitrates (PANs), and nitrogen oxides formed by sunlight-driven reactions. Particulate matter is characteristic of industrial smog, not photochemical smog.
Sedimentation is defined as what type of process in water treatment?
Explanation: Sedimentation is a primary physical water treatment process in which solid particles suspended in water settle to the bottom of a tank under gravity, clarifying the water before further treatment.
Droughts lead to wildfires due to which of the following reasons?
Explanation: Droughts contribute to wildfires through multiple mechanisms: they create arid, moisture-deficient conditions, dry out vegetation eliminating its natural fire resistance, and turn trees and shrubs into highly combustible fuel.
Which gas is primarily responsible for maintaining Earth's temperature through the greenhouse effect?
Explanation: Carbon dioxide (CO2) is the most significant greenhouse gas responsible for maintaining Earth's temperature by absorbing and re-emitting infrared radiation, preventing heat from escaping into space.
Which type of enzyme cuts DNA at specific recognition sequences?
Explanation: Restriction enzymes (also called restriction endonucleases) are molecular scissors that recognize and cut DNA at specific sequences called restriction sites. They are fundamental tools in genetic engineering.
What is the start codon in mRNA that initiates protein synthesis?
Explanation: AUG is the universal start codon in mRNA that signals the ribosome to begin translation of a protein. It codes for the amino acid methionine and marks the beginning of every polypeptide chain.
In which facility or container is milk stored upon arrival at dairy reception?
Explanation: At dairy reception facilities, fresh milk is stored in large refrigerated silo tanks (silos) that maintain optimal temperature and hygiene conditions until it is processed for pasteurization and packaging.
Which material is used along with steel as a coating layer in food can manufacturing?
Explanation: Food cans are made from steel coated with a thin layer of tin to prevent corrosion and rust. This is why food cans are commonly called "tin cans," even though the primary structural material is steel.
What is the structural composition of enzymes?
Explanation: Enzymes are biological catalysts made up of polypeptide chains (proteins). Their three-dimensional protein structure, especially the active site, determines their specificity and catalytic function.
Fruit ripening is primarily driven by which biological agents?
Explanation: Fruit ripening is primarily driven by enzymatic activity. Enzymes like cellulases, amylases, and pectinases break down cell walls and starches, softening the fruit and developing its flavor and color.
Sucrose is a disaccharide formed by the combination of which two monosaccharides?
Explanation: Sucrose (common table sugar) is a disaccharide formed by a glycosidic bond between one molecule of glucose and one molecule of fructose. It is produced naturally in plants through photosynthesis.
Two or more populations of different species living together in the same area are collectively called?
Explanation: In ecology, a community refers to two or more populations of different species that coexist and interact in the same habitat or geographic area, forming a biotic unit.
Which cellular organelle is known as the "factory" or site of ribosome production?
Explanation: The nucleolus is a dense region inside the cell nucleus where ribosomal RNA (rRNA) is synthesized and ribosomal subunits are assembled, earning it the name "ribosome factory."
Which is the densest planet in our Solar System?
Explanation: Earth is the densest planet in the Solar System with an average density of approximately 5.51 g/cm³. Its dense iron-nickel core and rocky mantle contribute to this high density.
S-waves (secondary seismic waves) can only pass through which medium after an earthquake?
Explanation: S-waves (shear waves) can only travel through solid materials because they require a medium that can resist shear stress. They cannot pass through liquids or gases, which is why the Earth's outer core (liquid) blocks S-waves.