Everyday Science — Past Papers — Part 4 MCQs with Explanations

The lungs exchange gases — they absorb oxygen (O₂) and release carbon dioxide (CO₂). This process is essential for respiration and energy production in the body.

Dalton’s Law of Partial Pressures was proposed by John Dalton . It states that the total pressure of a gas mixture equals the sum of the partial pressures of individual gases. Formula: Pₜ = P₁ + P₂ + P₃ + … It applies to non-reacting gases under suitable conditions.

Jabir ibn Hayyan , known as the " father of chemistry ." He was an Arab Chemist . Composition of Alchemy was written by Jabir Bin Hayyan . Notable ideas: Use of organic substances in chemistry Sulfur-mercury theory of metals Science of the balance Science of artificial generation

The pituitary gland is located at the base of the brain. It is below the hypothalamus . It sits in a hollowed-out area of the sphenoid bone called the sella turcica.

Sir Isaac Newton formulated the Three Laws of Motion . He presented them in 1687 in his famous work Principia Mathematica . Three Laws of Motion: First Law — Law of Inertia : An object remains at rest or in uniform motion unless acted upon by an external force. Second Law — Law of Acceleration : The net force on an object is related to its mass and acceleration. Third Law — Action and Reaction : For every action, there is an equal and opposite reaction.

Penicillin , the first true antibiotic , was discovered by Alexander Fleming . He made this discovery in 1928 at St. Mary’s Hospital, London . He found that a mould (Penicillium) killed bacteria in culture dishes. His findings were officially published in 1929 . First patient treated: Albert Alexander (12 February 1941)

Antonie van Leeuwenhoek is known as the Father of Microbiology . He was the first to observe and describe microorganisms using a microscope . He observed microscopic organisms in 1674 . His discoveries included bacteria, protozoa, and other microscopic life forms .

Aldehydes give a silver mirror test with Tollens' reagent . Tollens' reagent contains the diamminesilver(I) ion, [Ag(NH₃)₂]⁺ . The aldehyde is oxidized to a carboxylic acid/carboxylate , while Ag⁺ is reduced to metallic silver . The deposited silver forms a shiny silver mirror on the test tube.

Urbanization leads to clearing of forests for housing, infrastructure, and industries. Other causes include agriculture, logging, and mining.

Allergy is an abnormal immune response to harmless substances like dust or pollen . It occurs when the body reacts excessively to an allergen. This reaction involves the immune system producing antibodies . Thus, allergy is mainly due to an antigen–antibody reaction .

GPS is an abbreviation of the Global Positioning System . It is a satellite-based radio navigation system. Owned by the United States government. First launch: February 22, 1978

Blood groups are identified by specific antigens present on the surface of red blood cells. These antigens determine compatibility for blood transfusions . They are key to classifying blood types like A, B, AB, and O.

First Polio Vaccine Introduced: 1955 Developer: Dr. Jonas Salk Type: Inactivated Polio Vaccine (IPV) Oral Polio Vaccine (OPV): 1961 Developer of OPV: Dr. Albert Sabin

The Banyan tree is famous for developing aerial roots from its branches. These roots grow downward and may become supporting trunks . Because of its multiple root-like structures.

The stomach produces Hydrochloric Acid (HCl) as part of gastric juice. HCl creates a highly acidic environment with a pH of about 1.5–3.5 . It activates pepsinogen into pepsin . Pepsin helps break down proteins into smaller peptides.

The normal number of ribs in a human body is 24 ( 12 pairs ). Additional information : Upper ribs: True ribs (1–7 pairs) Lower ribs: False ribs (8–12 pairs) Floating ribs: Last 2 pairs (11–12)

Adrenal gland → Endocrine gland, not a digestive gland . Liver → Digestive gland; produces bile. Pancreas → Digestive gland; produces digestive enzymes .

Ammonia chemical formula is NH₃. It is a chemical compound made of nitrogen and hydrogen . It is a colorless gas with a strong , pungent smell. It is widely used in fertilizer production and various industrial processes.

Quicklime chemical formula is CaO . It is chemically known as calcium oxide . It is produced by heating limestone (CaCO₃) strongly. Quicklime reacts with water to form slaked lime, Ca(OH)₂ .

Washing soda , also known as sodium carbonate , has the chemical formula Na₂CO₃. It is commonly used in cleaning agents and water softeners. Washing soda is a whitish, odourless powder.

Bleaching powder: CaOCl₂ Chemical name: Calcium oxychloride. Main uses: Bleaching and disinfection. CaCl₂: Calcium chloride . Ca(OH)₂: Calcium hydroxide (slaked lime).

Vinegar mainly contains acetic acid (ethanoic acid) dissolved in water. The chemical formula of acetic acid is CH₃COOH . Household vinegar usually contains about 4–8% acetic acid . It gives vinegar its characteristic sour taste and sharp smell .

The chemical formula of baking soda is NaHCO ₃, which stands for sodium bicarbonate. The chemical name of baking soda is sodium hydrogen carbonate or sodium bicarbonate (NaHCO3). Sodium bicarbonate is non flammable Baking soda is basic in nature.

It is an ionic compound with the chemical formula NaCl. It representing a 1:1 ratio of sodium and chloride ions. Table salt is the granulated white salt seen in most saltshakers . It is typically mined from underground deposits. It is commonly known as Sodium chloride.

Smallest muscle: Stapedius . Location: Middle ear . Associated bone: Stapes . Function: Helps dampen excessive sound vibrations . Longest muscle: Sartorius .

The ovum (egg cell) is generally considered the largest cell in the human body. It is the female reproductive cell and can be seen with the naked eye as a tiny dot . The ovum is approximately 0.1 mm (100 micrometers) in diameter. In contrast, the sperm cell is one of the smallest human cells .

Largest part: Cerebrum . Hemispheres: Two — right and left . Main functions: Thinking, memory, intelligence, speech, and voluntary movement . Cerebellum: Mainly controls balance and coordination . Brainstem: Connects the brain with the spinal cord and controls vital functions .

The Aorta is the largest artery in the human body. It carries oxygen-rich blood from the left ventricle of the heart to the rest of the body . It is the main artery of the systemic circulatory system. The aorta branches into smaller arteries to supply blood to all body organs except the lungs. Additional information : Arterioles are the smallest branches of arteries . They carry oxygenated blood from arteries to the capillaries. Arterioles regulate blood flow and blood pressure by constricting or dilating.

Smallest bone: Stapes . Location: Middle ear . Three ear bones: Malleus, Incus, Stapes. Longest bone: Femur (thigh bone). Adult human skeleton: Usually 206 bones. Newborn: About 270 bones at birth; many later fuse together. Human skull: 22 bones (8 cranial + 14 facial)

The largest bone in the human body is th e femur (the thighbone) It is located in the upper leg, between the hip and the knee. It supports the weight of the body and helps you walk, run, and stand It is about 48 centimeters (18 inches) long . Additional information : The lowest part of the backbone is called the sacrum. The smallest bone is the stirrup (stapes). The strongest bone for its size is the lower jaw or mandible. Last updated by NA on 09-09-2026

The largest solid internal organ is the liver . It weighs approximately 3–3.5 pounds or 1.36–1.59 kilograms. It is about the size of a football . Additional information: Skin is the largest external organ of the human body

Marconi invented Radio . Radio was invented in 1895 . Guglielmo Marconi was an Italian inventor.

Meristematic cells are generally without a large vacuole. They are actively dividing cells found in the growing regions of plants. Their cytoplasm is dense, and they have a prominent nucleus. Large vacuoles develop as plant cells mature.

The kidneys purify the blood in the human body . They remove waste materials and extra water . Kidneys help maintain the body’s chemical balance. Each person has two kidneys . They produce urine as a waste product.

The Doppler Effect is the change in the observed frequency of sound due to the relative motion between the source and the observer . If the source and observer move toward each other , the observed frequency increases . If they move away from each other , the observed frequency decreases . A common example is the changing pitch of an ambulance siren as it passes by.

Alexander Graham Bell is credited as the inventor of the telephone . He was awarded the first successful patent for it. The telephone was invented in 1876 . Bell made the first-ever telephone call to his assistant Thomas Watson .

Washing soda , also known as sodium carbonate , has the chemical formula Na₂CO₃. It is commonly used in cleaning agents and water softeners. Washing soda is a whitish, odourless powder.

The Montgolfier brothers, Joseph-Michel and Jacques-Étienne , invented the hot-air balloon . Their first public demonstration took place in Annonay, France , on 4 June 1783 . In 1783 , a hot-air balloon carrying passengers successfully flew near Paris. The Montgolfier brothers are regarded as pioneers of human flight .

DNA stands for Deoxyribonucleic Acid . DNA is a biological molecule found in all living cells. It carries genetic information from parents to offspring . It controls growth, development, and body functions . DNA is present in the nucleus of cells (mainly in chromosomes). It is made of nucleotides arranged in a double helix structure . It was discovered by James Watson and Francis Crick ( 1953 structure model).

Liver produces bile , which helps in digestion of fats in the human body. Bile is a digestive fluid essential for fat breakdown. It is produced continuously by the liver . It is stored and concentrated in the gallbladder . It is released into the small intestine during digestion.