67th BPSC Prelims 2022
General Science Previous Year Questions (PYQs)

Detailed Explanation:

Pneumonia is an acute respiratory infection that causes inflammation of the alveoli (air sacs) in the lungs, filling them with fluid or pus, leading to breathing difficulty, cough, fever, and chest pain.

It is caused by bacteria, viruses, or fungi and primarily affects the respiratory system, not nerves, blood, or skin.

Therefore, pneumonia is an infection of the lungs, making Option 4 the correct answer.

Detailed Explanation:

AB blood group individuals possess both A and B antigens on their red blood cells but have no anti-A or anti-B antibodies in their plasma, allowing them to receive blood from all ABO groups without immune rejection.

O blood group is the universal donor (lacks A/B antigens), while A and B groups have specific antibodies that would attack incompatible blood types.

Therefore, AB can accept blood from all groups, making Option 3 the correct answer.

Detailed Explanation:

Ultrasonic waves (high-frequency sound waves above 20 kHz) are used in ultrasound imaging to monitor fetal growth in the womb. These waves are safe, non-invasive, and produce real-time images by reflecting off tissues.

X-rays involve ionizing radiation harmful to the fetus, microwaves are used in communication/heating, and ultraviolet rays cause skin damage—none are suitable for prenatal imaging.

Therefore, Ultrasonic waves are used for fetal imaging, making Option 3 the correct answer.

Detailed Explanation:

The pituitary gland is a pea-sized endocrine gland located at the base of the brain, attached to the hypothalamus by a stalk called the infundibulum. It sits in a bony cavity called the sella turcica.

Known as the "master gland," it regulates various hormonal functions including growth, metabolism, reproduction, and stress response by secreting hormones like GH, TSH, ACTH, FSH, LH, and prolactin.

Therefore, the pituitary gland is located in the brain, making Option 4 the correct answer.

Detailed Explanation:

Blood transfusion compatibility requires matching both ABO blood type and Rh factor to prevent immune reactions and hemolysis.

The Rh factor (Rh+ or Rh−) is a critical antigen on red blood cells; mismatched transfusion can trigger severe immune responses, especially in Rh-negative recipients receiving Rh-positive blood.

White cell count, red cell count, and donor race are not compatibility determinants for transfusion safety.

Therefore, Rh factor compatibility is essential, making Option 1 the correct answer.

Detailed Explanation:

The stem of a plant serves multiple functions: it transports water and nutrients from roots to leaves, distributes food (prepared by leaves during photosynthesis) to all parts, and stores food in the form of starch in tissues like parenchyma (e.g., potato, ginger, sugarcane stems).

While stems contribute to plant shape and contain lenticels for respiration, and green stems assist in photosynthesis, the question explicitly asks what stem helps with beyond distribution—making food storage the primary additional function.

Therefore, storing food is the key function alongside distribution, making Option 1 the correct answer.

Detailed Explanation:

Insectivorous plants (e.g., Venus flytrap, pitcher plant, sundew) grow in nitrogen-deficient soils like bogs, marshes, and wetlands. They compensate by trapping and digesting insects to obtain nitrogen and other essential nutrients.

Water, magnesium, and calcium deficiencies do not trigger insectivory; these nutrients are obtained through roots in normal soils.

Therefore, insectivorous plants grow in nitrogen-deficient soil, making Option 3 the correct answer.

Detailed Explanation:

During photosynthesis (daytime), plants absorb CO₂ and release O₂. At night, photosynthesis stops, but respiration continues—plants absorb O₂ and release CO₂, just like animals.

In enclosed or poorly ventilated spaces, this can slightly increase CO₂ levels and reduce oxygen concentration, making it uncomfortable to sleep under trees indoors or in confined areas.

Therefore, trees liberate carbon dioxide at night through respiration, making Option 3 the correct answer.

Detailed Explanation:

Bacteria are the primary microorganisms responsible for decomposing biodegradable waste through natural processes like composting and anaerobic digestion, converting organic matter into useful substances like manure, biogas, and nutrients.

Viruses infect living cells and cannot decompose waste; nuclear proteins are cellular components with no role in waste breakdown; radioactive substances cause contamination rather than beneficial decomposition.

Therefore, bacteria are the agents of biodegradation, making Option 1 the correct answer.

Detailed Explanation:

Water moves from soil into plant roots through osmosis, a process where water molecules pass through a semi-permeable membrane (root cell walls) from a region of higher water concentration (soil) to lower water concentration (root cells).

Diffusion involves movement of particles from high to low concentration but does not require a semi-permeable membrane. Absorption is a general term for uptake, while transpiration is water loss from leaves through stomata—not water uptake.

Therefore, osmosis is the specific physical process for water uptake by roots, making Option 4 the correct answer.

Detailed Explanation:

Liquefied Petroleum Gas (LPG) is primarily composed of propane (C₃H₈) and butane (C₄H₁₀), with butane being the major constituent in most commercial LPG blends used for cooking and heating.

Methane is the main component of natural gas (CNG), not LPG, while ethane is present only in trace amounts in petroleum gases.

Therefore, butane is the major constituent of LPG, making Option 4 the correct answer.

Detailed Explanation:

Graphite and diamond are allotropes of carbon—different physical forms of the same element. Both consist of pure carbon atoms and thus undergo identical chemical reactions (e.g., combustion in oxygen to form CO₂).

They differ drastically in crystal structure (graphite: hexagonal layers; diamond: tetrahedral lattice), hardness (graphite: soft; diamond: hardest natural material), and electrical conductivity (graphite: conducts; diamond: insulator)—eliminating Options 1, 2, and 3.

Therefore, only their chemical reactivity is identical, making Option 4 the correct answer.

Detailed Explanation:

Acrylic is a synthetic polymer derived from petrochemicals (acrylonitrile), not cotton, and is known for its wool-like properties, not silk-like shine.

Rayon (viscose) is the fiber actually called artificial silk because it is derived from natural cellulose (wood pulp/cotton linters) and has a silk-like sheen and drape.

Option 1 is correct (cotton absorbs moisture for summer comfort), Option 2 is correct (polycarbonate is used in CDs for its transparency and durability), and Option 4 is correct (Teflon/PTFE provides non-stick coating).

Therefore, Statement 3 is incorrect as acrylic is not prepared from cotton nor called artificial silk, making Option 3 the correct answer.

Detailed Explanation:

Option 1 is Incorrect: Atoms are electrically neutral because protons (positive) are in the nucleus and electrons (negative) orbit outside it—electrons are NOT inside the nucleus.

Options 2, 3, and 4 are Correct: Electrons are negatively charged with negligible mass; atomic number equals proton count; isotopes have applications in nuclear energy, medicine (radiotherapy), and carbon-14 dating.

Therefore, more than one statement is incorrect/correct, making Option 5 the correct answer.

Detailed Explanation:

pH scale measures acidity and basicity: pH < 7 indicates acidic, pH = 7 is neutral, and pH > 7 indicates basic (alkaline) solutions.

Basic solutions have excess hydroxide ions (OH⁻), resulting in pH values greater than 7. Examples include sodium hydroxide, potassium hydroxide, and ammonia solutions.

Therefore, only basic solutions have pH > 7, making Option 2 the correct answer.

Detailed Explanation:

The triple point is a unique thermodynamic condition where all three phases of a substance—solid, liquid, and gas—coexist in equilibrium at a specific temperature and pressure.

Boiling point (liquid to gas), melting point (solid to liquid), and freezing point (liquid to solid) each involve transitions between only two phases, not all three simultaneously.

Therefore, the triple point is where all three states coexist, making Option 4 the correct answer.

Detailed Explanation:

Isotopes are atoms of the same element with identical atomic numbers (same number of protons) but different mass numbers due to varying numbers of neutrons. For example, Carbon-12 and Carbon-14 both have 6 protons but differ in neutron count (6 vs 8), resulting in different mass numbers (12 vs 14).

The number of protons and electrons remains constant within isotopes of an element, as changing protons would create a different element entirely, and neutral atoms maintain equal protons and electrons.

Therefore, isotopes differ only in mass number, making Option 2 the correct answer.

Detailed Explanation:

Cement is manufactured using multiple key ingredients, making Option 5 the correct choice. The primary component is limestone (~60–65%), which provides calcium oxide. Silica clay (~20–25%) supplies silica, alumina, and iron oxide. Gypsum (~3–5%) is added post-burning to regulate setting time.

Since limestone, silica clay, and gypsum are all essential ingredients—not just one—the answer cannot be a single option.

Therefore, more than one ingredient is correct, making Option 5 the correct answer.

Detailed Explanation:

The mass number (A) of a nucleus is defined as the sum of protons and neutrons in the nucleus. It is a count (dimensionless integer), not the actual mass in kilograms or atomic mass units.

Option 2 incorrectly states "total mass" (which would have units); Option 3 is false—mass number is close to but not always more than atomic weight; Option 4 is absurd—mass number is always greater than atomic number (Z).

Therefore, Option 1 is the correct answer.

Detailed Explanation:

Soap film has two surfaces (top and bottom) that reflect light. When white light hits these surfaces, waves reflected from the top and bottom surfaces overlap and interfere, causing certain wavelengths to cancel out and others to amplify, producing the vibrant colours observed.

Diffraction occurs when light bends around edges, refraction is bending due to medium change, and polarization restricts light vibrations to one plane—none explain the colour pattern in soap films.

Therefore, interference of light is responsible for soap film colours, making Option 4 the correct answer.