BECE 2005 Integrated Science Objective Questions and Answers

Solution: H₂ denotes a single molecule composed of two hydrogen atoms bonded together, not separate molecules, elements, or ions.

Solution: Heating increases atomic vibration, causing atoms to occupy more space and expand the metal. Electron count, potential energy, or atom proximity don't directly cause expansion.

Solution: A fuse contains a wire that melts when excess current flows, breaking the circuit. Earth wires ground excess charge, lightning conductors divert strikes, and switches manually control circuits.

Solution: In a plane mirror, the image forms as far behind the mirror as the object is in front. Thus, total distance = 20 cm (object to mirror) + 20 cm (mirror to image) = 40 cm.

Solution: A bulb lights only in a complete (closed) circuit with a power source and uninterrupted path for current. Option B depicts such a circuit.

Solution: Sunlight drives photosynthesis (chemical energy), weather (wind/water energy), and fossil fuel formation. Other options are secondary energy manifestations.

Solution: As the mango falls, height (and potential energy) decreases while speed (kinetic energy) increases. Minor sound/heat may occur, but kinetic energy is primary.

Solution: Electricity transfers energy to appliances to perform work (e.g., heating, motion). Force is a push/pull, while generators and machines utilize energy.

Solution: Work = Force × Distance = 2 N × 10 m = 20 J (joules). Energy transfer occurs in the direction of force application.

Solution: In levers, "load distance" (X) is the distance from the fulcrum to the load (stone). Effort distance is from fulcrum to where force is applied.

Solution: Mechanical advantage increases when effort distance (Y) > load distance (X), reducing required effort. Lever principle: Effort × Y = Load × X.

Solution: Omnivores consume both plant and animal matter ("all kinds of food"). Food preparation (raw/fresh/cooked) doesn't define dietary classification.

Solution: A "balanced" diet provides carbohydrates, proteins, fats, vitamins, and minerals in proper proportions for health. Other options describe taste, preparation, or single components.

Solution: Kwashiorkor results from severe protein deficiency, causing edema and stunted growth. Goiter (iodine), rickets (vitamin D), and scurvy (vitamin C) involve other nutrients.

Solution: Fehling’s test detects reducing sugars (not proteins). For proteins, Biuret test is used (violet/purple). Note: Original document lists "D. brick-red" in solutions, implying a possible question error. Standard protein tests use Biuret (purple), not Fehling’s.

Solution: Chlorophyll (a pigment in chloroplasts) absorbs sunlight for photosynthesis. Chloroplasts are organelles containing chlorophyll; phloem/xylem transport nutrients/water.

Solution: The liver detoxifies chemicals (e.g., ammonia → urea), metabolizes drugs, and produces bile. Kidneys filter waste; bladder stores urine; duodenum digests food.

Solution: Cellular respiration breaks down glucose with oxygen to release energy (ATP), producing CO₂ and H₂O. Photosynthesis reverses this process.

Solution: Chlorine disinfects water by destroying bacteria/viruses. Settling particles involves coagulation (e.g., alum); softening removes minerals; taste is improved by aeration/filtration.

Solution: Rainwater (I) is least contaminated (atmospheric). Borehole (IV) is deep groundwater, then shallow well (III), and streams (II) are most exposed to pollutants.

Solution: A saturated solution holds the maximum solute at that temperature. Concentrated/dilute describe amount dissolved; homogeneous means uniform mixture.

Solution: Solubility increases with temperature. Cooling reduces solubility, causing excess sugar to crystallize. Sugar dissolves in both hot/cold water, but better in hot.

Solution: Water dissolves ionic/polar compounds due to its polarity. It isn't the purest (contains dissolved gases/minerals) nor exclusive to living cells, but its solvent versatility is unmatched.

Solution: Oxygen has -2 charge each. For SO₂: S + 2(-2) = 0 (neutral molecule). Thus, S = +4.

Solution: Humus (decayed organic matter) improves soil structure, nutrient retention, and water-holding capacity, directly supporting plant growth.

Solution: Gravel has large pores that drain water quickly and lacks organic matter/nutrients. Roots need sustained moisture and nutrients, which gravel cannot provide.

Solution: Plasmodium (malaria parasite) infects red blood cells. Lice/tick are ectoparasites; tapeworms live in intestines.

Solution: Female Anopheles mosquitoes transmit Plasmodium while feeding on blood. Males feed on nectar; black flies spread river blindness; tsetse flies spread sleeping sickness.

Solution: Guinea worm larvae enter through skin when wading in water. Wearing footwear blocks transmission. Bush clearing targets vector habitats for other diseases (e.g., malaria).

Solution: Hygrometers measure humidity. Anemometers measure wind speed; barometers measure air pressure; hydrometers measure liquid density.

Solution: The sidereal month (complete orbit relative to stars) is ~27.3 days, often rounded to 28 days in basic science. The synodic month (full moon cycle) is ~29.5 days.

Solution: Steel is an alloy (solid solution) of iron (solid) and carbon (solid), making it a solid-solid mixture.

Solution: Sodium (Na) is a soft, reactive metal. Carbon/Nitrogen/Sulphur are non-metals.

Solution: Ornament metals (e.g., gold, silver) resist tarnishing/corrosion due to low reactivity. They are highly conductive, ductile, and malleable.

Solution: Refrigeration slows microbial growth by reducing temperature. Canning uses heat sterilization; drying/pickling remove water or alter pH.

Solution: Platelets (thrombocytes) form clots to stop bleeding. CO₂ transport is by plasma/RBCs; disease fighting by WBCs; temperature regulation involves blood flow/sweating.

Solution: Streamlined shape minimizes drag by allowing water to flow smoothly. Fins aid propulsion; gills are for respiration; oxygen use is unrelated to resistance.

Solution: Gravity accelerates the person downward after the jump. Magnetic force affects compasses, not free fall; atmospheric effects are negligible for short jumps.

Solution: Density = Mass / Volume = 35.0 g / 5.0 cm³ = 7.0 g cm⁻³. Displaced water volume equals the metal’s volume.

Solution: Oxygen moves from high concentration (alveoli) to low concentration (blood) via diffusion. Osmosis involves water; capillarity is liquid rise in tubes; suction is mechanical.