BECE 2024 Integrated Science Past Question

Explanation: Non-renewable energy sources are those that are finite and cannot be replenished on a human timescale. Coal and Uranium-236 are fossil fuels and a nuclear fuel, respectively, and are considered non-renewable. Solar and wind are renewable energy sources.

Explanation: An atom is the basic unit of an element, retaining the chemical properties of that element. Ions are charged atoms or molecules, molecules are formed from two or more atoms, and protons are subatomic particles.

Explanation: The oil spill created a layer on the water surface, preventing mosquito larvae from accessing oxygen and thus controlling their population. This is an example of environmental control, which involves modifying the environment to manage pests. Biological control uses natural enemies, chemical control uses pesticides, and genetic control involves altering the genetic makeup of the pest.

Explanation: Grasshopper management is important due to the damage they cause to crops, disruption of ecosystems, and potential harm to livestock if they consume affected plants. Incomplete metamorphosis is a characteristic of grasshoppers, but it is not a reason for their management; rather, it describes their life cycle.

Explanation: Newton's third law of motion states that for every action, there is an equal and opposite reaction. When the gun is fired, it exerts a forward force on the bullet (action), and the bullet exerts an equal and opposite backward force on the gun (reaction), which is felt by the hunter as recoil.

Explanation: Loudspeakers, compasses, and some types of alarms utilize the principles of magnetism in their operation. LCD TVs primarily work on the principle of liquid crystals and light, not magnetism.

Explanation: The number of electron shells an element has is related to its period in the periodic table. To determine the number of electron shells, we look at the electron configuration. Potassium (\(_{19}\)K) has electron configuration 2, 8, 8, 1, which means it has 4 electron shells. Aluminum (\(_{13}\)Al) has 3 shells (2, 8, 3), Phosphorus (\(_{15}\)P) has 3 shells (2, 8, 5), and Boron (\(_{5}\)B) has 2 shells (2, 3).

Explanation: Maintaining good health in livestock involves a combination of practices: having vaccination schedules to prevent diseases, providing a balanced diet for proper nutrition, and ensuring good sanitation to prevent the spread of diseases. All three activities are crucial for the well-being of the animals.

Explanation: Consuming expired food or drinks can lead to food poisoning due to the potential growth of harmful bacteria or the formation of toxins. The other options are not direct hazards associated with consuming expired goods.

Explanation: Red litmus paper turns blue in basic solutions. Solution A changed red litmus paper to blue, indicating it is a basic solution. Car battery fluid (sulfuric acid) and orange juice (citric acid) are acidic. Salt solutions are typically neutral. Baking soda (sodium bicarbonate) is a base.

Explanation: \(Mg(OH)_{2}\) is the chemical formula for magnesium hydroxide, which is commonly known as Milk of Magnesia. It is used as an antacid to relieve stomach upset.

Explanation: Heat transfer in fluids (liquids and gases) primarily occurs through convection, which is the movement of the fluid itself, carrying thermal energy. In the case of water being heated on a stove, the warmer, less dense water rises, and cooler, denser water sinks, creating convection currents that distribute heat throughout the water. Radiation is heat transfer through electromagnetic waves, emission is the process of giving off something (like light or heat), and conduction is heat transfer through direct contact.

Explanation: Air is a mixture of gases, predominantly nitrogen (about 78%) and oxygen (about 21%), with smaller amounts of other gases. In this mixture, nitrogen is present in the largest proportion and acts as the solvent in which other gases are dissolved.

Explanation: A rainbow is a natural phenomenon that demonstrates the dispersion of sunlight into its constituent colors as it passes through water droplets, which act like prisms, splitting the light. An eclipse is an astronomical event, rainfall is precipitation, and an echo is the reflection of sound waves.

Explanation: When a stick is dipped into water, it appears to bend towards the surface due to the refraction of light. Light rays from the part of the stick in the water bend as they pass from water to air, creating the illusion that the stick is bent.

Explanation: Electric irons, kettles, and water heaters are all designed to convert electrical energy into heat energy for various purposes like ironing clothes, boiling water, and heating water.

Explanation: The consequences of the greenhouse effect include rising global temperatures, which can lead to the flooding of coastal cities due to thermal expansion of water and melting ice, desertification of fertile areas, and an increased frequency and intensity of extreme weather events like storms. Increased use of fossil fuels is a cause of the greenhouse effect, not a consequence on humans.

Explanation: When an insecticide is sprayed, it turns into a gas or fine particles that spread through the air to reach the cockroaches. This process of spreading from an area of higher concentration to lower concentration is called diffusion. Osmosis is the movement of water across a semipermeable membrane, absorption is the process of taking something in, and radiation is energy transfer through waves or particles.

Explanation: When a substance is heated, its density, temperature, and usually its volume change. However, the mass of the substance remains constant, assuming no material is added or removed.

Explanation: Kinetic energy is the energy of motion. Potential energy is stored energy, mechanical energy is the sum of kinetic and potential energy, and electrical energy is energy associated with electric charge.

Explanation: Ionic bonds are formed by the transfer of valence electrons from a metal atom (like sodium) to a non-metal atom (like chlorine), resulting in the formation of ions.

Explanation: Hybrid vigour (heterosis) is the improved or increased function of any biological quality in a hybrid offspring. It is typically associated with cross-breeding between different pure lines.

Explanation: Proteins are essential for growth and the repair of body tissues.

Explanation: Earthworms belong to the phylum Annelida, which is characterized by segmented bodies.

Explanation: Trace elements (or micronutrients) are required by plants in very small quantities. Zinc is a trace element, while Phosphorus, Potassium, and Nitrogen are macronutrients, required in larger quantities.

Explanation: Pre-planting operations are activities carried out before crops are planted. Ploughing is a form of land preparation done before planting. Harvesting, pruning, and weeding are post-planting operations.

Explanation: In traditional film cameras, light energy strikes the film, causing a chemical change (exposure) that records the image. In digital cameras, light energy is converted to electrical signals by a sensor.

Explanation: A pinhole camera forms an image that is inverted (upside down) and real (can be projected onto a screen). The image is typically smaller than the object, not larger.

Explanation: A hygrometer is an instrument used to measure the amount of water vapor in the air (humidity). An anemometer measures wind speed, a barometer measures atmospheric pressure, and a hydrometer measures the specific gravity of liquids.

Explanation: Non-metals are generally poor conductors of heat and electricity, are brittle (not malleable or ductile), and have lower melting and boiling points compared to metals.

Explanation: Crop rotation is an effective farming practice for controlling pests and diseases as it breaks their life cycles and reduces their build-up in the soil.

Explanation: Measles is a highly contagious viral disease for which an effective vaccine is available. While vaccines exist for cholera and typhoid, malaria is prevented by other means (like mosquito control and antimalarial drugs).

Explanation: Photosynthesis is the process by which green plants use sunlight, water, and carbon dioxide to synthesize glucose (food).

Explanation: Discharging industrial waste, spraying insecticides (which can run off into water), and dumping refuse directly pollute water bodies. Watering plants is a necessary activity for agriculture and does not inherently cause water pollution unless contaminated water sources are used or excessive fertilizers/pesticides are involved (which isn't implied by "watering of plants").

Explanation: After fertilization, the ovary of a flower ripens and develops into a fruit, while the ovules within the ovary develop into seeds.

Explanation: Decomposition of organic matter by microorganisms produces carbon (IV) oxide. Photosynthesis consumes carbon (IV) oxide, transpiration is the release of water vapor, and capillarity is the movement of water in narrow spaces.

Explanation: Soil reaction (pH) is a chemical property of soil, determined by the concentration of hydrogen ions. Water retention, porosity, and soil structure are primarily physical properties.

Explanation: Indiscriminate spitting can spread pathogens and promote the spread of diseases. Regular hand washing, proper waste disposal, and practicing social distancing are all practices that help prevent the spread of diseases.

Explanation: Polymerization is a process in which relatively small molecules, called monomers, chemically combine to produce a very large chain-like or network molecule, called a polymer. Plastics are polymers.

Explanation: Roots are the part of the plant that are typically found underground and are responsible for absorbing water and essential mineral salts from the soil.