BECE 2000 Integrated Science Objective Questions and Answers

Solution: Fins are specialized appendages in fish that provide propulsion, steering, and stability in water, making them essential for movement.

Solution: A galaxy is a gravitationally bound system of stars, gas, dust, and dark matter. Meteors, meteorites, planets, and solar systems are smaller components or phenomena within galaxies.

Solution: Atoms are the smallest units of matter that retain the properties of an element. Compounds, elements, electrons, and ions are all composed of or derived from atoms.

Solution: Melting ice involves a phase change (solid to liquid) without altering the chemical composition of water. The other options involve irreversible chemical reactions forming new substances.

Solution: Kidneys filter blood to remove urea, excess ions, and water as urine. The anus/rectum eliminates undigested food (feces), not metabolic waste.

Solution: A valid food chain starts with producers (green plants), followed by herbivores (grasshopper), then primary carnivores (lizards), and secondary carnivores (snakes).

Solution: Electric bells use electromagnets to rapidly move a striker against a bell. Electric irons use heating elements, not electromagnets for core function.

Solution: Hair/fur is a defining characteristic of mammals. Egg-laying (monotremes) is rare; feathers, beaks, and cold-bloodedness are traits of birds/reptiles.

Solution: Ticks are external parasites that attach to dogs to feed on blood. Capsids are insects, guinea worms/plasmodium infect humans, and tapeworms are internal parasites.

Solution: Camphor transitions directly from solid to vapor (sublimation) when heated. The others melt or decompose.

Solution: Fertilization (fusion of gametes) produces a zygote, which later develops into an embryo within the seed.

Solution: Clay particles are tiny and tightly packed, minimizing air spaces and maximizing water retention through capillary forces.

Solution: Bilharzia (schistosomiasis) spreads via water contaminated by feces carrying parasitic worms. Malaria is vector-borne, not directly water-contamination related.

Solution: Kelvin = Celsius + 273. Thus, 20°C + 273 = 293 K.

Solution: The Sun is a star that generates light via nuclear fusion. Planets (Mars/Venus), moons, and meteorites reflect light.

Solution: Shedding leaves minimizes water loss through transpiration (evaporation from leaf surfaces), crucial in arid environments.

Solution: A filament bulb uses electrical resistance to heat a tungsten wire until it glows (incandescence), converting electricity to light.

Solution: Capillaries are microscopic vessels (one cell thick) where gas/nutrient exchange occurs. Arterioles/venules are larger.

Solution: Sneezing is an involuntary, rapid response to nasal irritants, mediated by the spinal cord. Others require conscious effort.

Solution: Decantation allows sediments to settle, followed by pouring off clean water. Precipitation (coagulation) is also used but decantation is primary for solid separation.

Solution: The reaction is: CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂. Carbon dioxide is the gaseous product.

Solution: Sweating cools the body via evaporation. High temperatures trigger this response; humidity reduces evaporation efficiency.

Solution: Cassava is commonly grown from stem cuttings (vegetative propagation). Others are typically grown from seeds.

Solution: Food contains energy in chemical bonds (e.g., carbohydrates, fats), released during metabolic reactions.

Solution: Enzymes (proteases) break proteins into amino acids, which are absorbed into the bloodstream.

Solution: Magnetic field lines converge at the poles, creating the strongest attraction. The center has negligible magnetism.

Solution: Enzymes (e.g., amylase, protease) catalyze the breakdown of complex food molecules into absorbable units.

Solution: Conduction involves direct molecular transfer in solids. Convection requires fluids (liquids/gases), and radiation occurs in vacuum/air.

Solution: AIDS (HIV) spreads via unprotected sex. Cholera, polio, and TB spread through contaminated water/air; malaria via mosquitoes.

Solution: Heating increases molecular motion, accelerating solvent-sugar interactions. Stirring/grinding also help, but heating has the most significant impact on solubility kinetics.

Solution: CO₂ is a key reactant in photosynthesis: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂. Chlorophyll is a catalyst, sunlight is energy, oxygen is a product.

Solution: In our solar system, planets orbit the Sun due to its gravitational dominance (99.8% of the system’s mass).

Solution: Legumes host nitrogen-fixing bacteria (Rhizobium) in root nodules, enriching soil nitrogen for subsequent crops.

Solution: Female Anopheles mosquitoes transmit Plasmodium (malaria parasite) via bites. Tsetse flies transmit trypanosomes (sleeping sickness).

Solution: Surface tension creates a "skin" on water, allowing lightweight larvae to float. Density/viscosity affect submersion, not flotation.

Solution: Sharing personal items (towel/comb) spreads skin infections, lice, or fungi. Other options promote hygiene.

Solution: Dilution reduces solute concentration per unit volume. "Concentrated" is the opposite; saturation relates to maximum solute dissolution.

Solution: Protons carry positive charge. Neutrons are neutral. Electrons (negative) are not counted here. Thus, 4 protons = 4 positive particles.

Solution: All living things respire (release energy) and grow. Not all make their own food (e.g., animals are heterotrophs).

Solution: Converging (convex) lenses correct hyperopia (long-sightedness) by focusing light onto the retina. Short-sightedness requires diverging lenses.