I) Respiration is the biochemical process by which living organisms break down organic substances, like glucose, to release energy for metabolic activities.

Mass ($m$) = $100 \text{ kg}$
Velocity ($v$) = $8 \text{ m/s}$

The kinetic energy is $\boxed{\text{3200 J}}$.

2(c)

i) Electronic configuration is the distribution of electrons of an atom or molecule in atomic or molecular orbitals. It describes how electrons are arranged around the nucleus.

ii)

• Protons are positively charged particles found in the nucleus of an atom, while electrons are negatively charged particles that orbit the nucleus.
• Protons have a significantly larger mass compared to electrons (approximately 1836 times heavier).

2(d)
Four importance of soil water:

• It is essential for plant growth as it dissolves nutrients for absorption.
• It helps in regulating soil temperature.
• It facilitates the decomposition of organic matter by microorganisms.
• It is a component of the soil solution, which transports nutrients.

3. a (i)
α) Ecosystem: An ecosystem is a community of living organisms (biotic components) interacting with each other and with their non-living environment (abiotic components) in a particular area.
β) Adaptation: Adaptation is a heritable trait that helps an organism survive and reproduce in its specific environment. It can be structural, physiological, or behavioral.
μ) Habitat: A habitat is the natural environment or home where a particular organism lives. It provides the necessary resources for survival, such as food, water, and shelter.

3. a (ii)
Three adaptations of a fish in its habitat:

• Streamlined body shape: Reduces drag and allows for efficient movement through water.
• Gills: Specialized organs for extracting oxygen from water.
• Fins: Used for propulsion, steering, and maintaining balance in water.

3. b.
Four uses of the periscope:

• Used in submarines to see above the water surface.
• Used in tanks to observe the surroundings from inside.
• Used in trenches during warfare to observe enemy positions without exposing oneself.
• Used by spectators in crowded events to see over obstacles.

3. c (i)

• Hard water contains a high concentration of dissolved mineral ions, primarily calcium ($Ca^{2+}$) and magnesium ($Mg^{2+}$) ions.
• Soft water contains a low concentration of these mineral ions.

3. c (ii)
Two advantages of hard water over soft water:

• It provides essential minerals like calcium and magnesium, which are beneficial for human health (e.g., bone development).
• It has a better taste for drinking due to the dissolved minerals.

3. d (i)
Fertilizer application is the process of adding nutrients to the soil or directly to plants to enhance plant growth and crop yield.

3. d (ii)
Four methods of fertilizer application:

• Broadcasting: Spreading fertilizer uniformly over the entire field.
• Placement: Applying fertilizer in concentrated bands near the seeds or plants.
• Foliar application: Spraying liquid fertilizer directly onto the leaves of plants.
• Fertigation: Applying fertilizer dissolved in irrigation water.

4. a.
Four importance of the carbon cycle:

• It regulates the Earth's climate by controlling the concentration of carbon dioxide in the atmosphere.
• It is essential for photosynthesis, providing carbon dioxide for plants to produce organic matter.
• It facilitates the transfer of energy through ecosystems as carbon compounds move through food chains.
• It is crucial for the formation of fossil fuels (coal, oil, natural gas) over geological time.

4. b.

i) Soil structure: Refers to the arrangement of soil particles (sand, silt, clay) into aggregates or peds. It influences water infiltration, aeration, and root penetration.

ii) Soil texture: Describes the relative proportions of different-sized mineral particles (sand, silt, and clay) in a soil. It determines how water and nutrients are held.

iii) Soil porosity: The volume of pore spaces (empty spaces) within the soil, which can be filled with air or water. It affects aeration and water retention.

iv) Soil capillarity: The ability of soil to draw water upwards against the force of gravity through its pore spaces, due to adhesive and cohesive forces.

4. c. (i)
A compound is a substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio.

4. c. (ii)
Three differences between a compound and a mixture:

• In a compound, elements are chemically bonded, forming new substances with different properties, while in a mixture, substances are physically combined and retain their original properties.
• A compound has a fixed composition by mass, whereas a mixture has a variable composition.
• The components of a compound can only be separated by chemical means, while the components of a mixture can be separated by physical means.

4. d. (i)
Frictional force is a force that opposes motion or attempted motion between two surfaces in contact.

4. d. (ii)
Three applications of friction:

• Walking: Friction between shoes and the ground allows us to walk without slipping.
• Braking: Friction in brakes helps to slow down or stop vehicles.
• Writing: Friction between a pen/pencil and paper allows ink/graphite to be deposited.

5. a. (i)

• Transpiration is the process by which plants release water vapor into the atmosphere, primarily through stomata on their leaves. It is mainly a physical process driven by water potential gradients.
• Photosynthesis is the process by which green plants and some other organisms convert light energy into chemical energy, synthesizing sugars from carbon dioxide and water. It is a biochemical process.