BECE 2023 Integrated Science Objective Questions and Answers

Solution: Stirring soil on vegetable beds helps to loosen the soil, allowing more air to circulate (aeration), improving water drainage and penetration, and encouraging the activity of beneficial soil organisms. It also helps reduce weed growth. Therefore, all listed effects are benefits of stirring soil.

Solution: Crop production principles cover activities from preparing the land to controlling pests and diseases while the crop is growing. Harvesting and processing occur after the crop has been grown and are considered post-production activities, not principles of crop production itself.

Solution: The chemical formula H₂O₂ represents Hydrogen Peroxide. It contains 2 hydrogen atoms and 2 oxygen atoms, for a total of 4 atoms.

Solution: Silicon is a semiconductor element widely used in the manufacturing of electronic components like transistors, diodes, and integrated circuits.

Solution: An anemometer is an instrument specifically used to measure wind speed.

Solution: Artificial satellites have various applications, including facilitating communication (I), assisting in the exploration for resources like oil and gas (II), and conducting studies related to weather and climate (meteorological studies) (III).

Solution: Venus is the brightest planet in our solar system as seen from Earth due to its dense cloud cover which reflects sunlight effectively.

Solution: The SI unit for pressure is the Pascal (Pa), which is a derived unit (defined in terms of other base units). The kilogram (kg), Kelvin (K), and second (s) are all base SI units for mass, temperature, and time, respectively.

Solution: In an N-P-N transistor, the base is made of p-type semiconductor material. The majority charge carriers in the base are holes.

Solution: Contour ploughing is a farming practice used on sloppy lands to reduce soil erosion. Ploughing along the contours of the land creates furrows that act as barriers, slowing down the flow of water and preventing soil runoff.

Solution: Condensation is the process by which a substance changes from a gaseous state (like steam) to a liquid state. Melting is solid to liquid, evaporation is liquid to gas, and boiling is a type of evaporation.

Solution: When a ray of light travels from a less dense medium (e.g., air) to a denser medium (e.g., water), it slows down and bends towards the normal line due to refraction.

Solution: A separating funnel is used to separate immiscible liquids like water and vegetable oil, which form distinct layers when mixed.

Solution: Increase in bushfires is generally caused by dry vegetation and climate conditions, not soil erosion. The other options are typical effects of erosion.

Solution: A streamline shape is designed to reduce resistance when moving through a fluid (liquid or gas). This shape allows the fluid to flow smoothly around the object.

Solution: Pest control is often categorized as crop protection, not a basic cultural practice like nursing, weeding, or mulching.

Solution: Animal cells typically contain a vacuole (though usually smaller than in plant cells) and a nucleus. Chloroplasts and cell walls are not found in animal cells.

Solution: A galaxy is a vast system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. A solar system consists of a star and the objects that orbit it. Astronomy is the study of celestial objects. A comet is an icy, small Solar System body.

Solution: The formation of a Ca²⁺ ion involves a calcium atom losing 2 electrons. Potassium loses 1 electron (K⁺), Sulfur gains 2 electrons (S²⁻), and Fluorine gains 1 electron (F⁻).

Solution: Potential energy \( PE = mgh = 70 \times 10 \times 15 = 10,500\, \text{J} \).

Solution: A mixture is a substance comprising two or more components not chemically bonded. Salt solution is a mixture of salt and water. The others are chemical compounds.

Solution: Boiling a green leaf in water (and then in ethanol) extracts the chlorophyll, allowing the iodine test to reveal the presence of starch more clearly.

Solution: 500 g is the greatest mass among the options. The rest are smaller when converted to grams: 0.05 g, 50 mg = 0.05 g, and 0.01 kg = 10 g.

Solution: 50 mg is the least mass. It equals 0.05 g, which is smaller than all the other values provided.

Solution: Density is mass divided by volume. If the volume is constant, the product with the highest mass will have the highest density — which is 500 g.

Solution: Density = \( \frac{500}{250} = 2 \, \text{g/cm}^3 \).

Solution: Acids turn blue litmus paper red (not red to blue, so I is incorrect). They can be neutralized by bases (II), and citrus fruits contain acids (III).

Solution: Clayey soil has the smallest particle size and a high surface area, allowing it to retain more water and gain more weight per unit than the other types.

Solution: The image formed by a plane mirror is always virtual, upright, and the same size as the object.

Solution: Using Ohm’s Law, \( V = IR = 3 \times 4 = 12\, \text{V} \).

Solution: The nucleus of an atom contains protons (positively charged) and neutrons (neutral). Electrons orbit around the nucleus.

Solution: Capacitors store energy in an electric field and are typically made from conductors and dielectrics, not semiconductor material.

Solution: Water availability is crucial for plant growth. Without adequate water, even with labour and market proximity, vegetable crops cannot thrive.

Solution: One of the main benefits of technology in industry is the provision of machines, which increase productivity and efficiency.

Solution: Density = \( \frac{10,000}{200} = 50\, \text{kg/m}^3 \)

Solution: Thinning out ensures seedlings have enough space and resources to grow properly by removing the weaker ones.

Solution: Mixed cropping allows simultaneous cultivation of different crops on the same land, maximizing space and resources.

Solution: Arteries have thick walls and narrow lumens to handle high pressure from the heart. Most veins have wider lumens and valves.

Solution: Plaque is a sticky film of bacteria that forms on teeth. If not removed, it can harden and become dark around the gums.

Solution: Weather refers to short-term changes in the atmosphere, while climate is the long-term average.