Environmental Science: Combustion, Conductivity, Climate, and Photosynthesis
Objective 7: Environmental Contamination by Combustion
The combustion process generates toxic gases, such as carbon dioxide. It also generates heat, affecting the environment and producing smog. This contributes to the greenhouse effect, which is the increase in temperature that occurs in the terrestrial globe due to environmental contamination.
Objective 8: Electrical Conductivity
Electrical currents are classified as chemical properties. When passed through solutions of acids or salts, they produce a physical phenomenon. Atoms are composed of protons (positive), neutrons (neutral), and electrons (negative). The union of atoms forms charged molecules. The union between atoms and molecules allows for chemical bonds.
- Ion: An atom that is electrically charged, allowing it to capture or transfer electrons.
- Electrolytes: Substances in a solution that conduct electrical currents.
- Conductive Materials: Steel, water, copper, iron, graphite, salt water, and aluminum.
- Nonconductive Materials: Rubber, wood, glass, and plastic.
Electrolysis is a process that separates the ions of an electrolyte using an electric current passing through the substance.
- Batteries and Accumulators: Dry and alkaline batteries.
- Galvanization or Electroplating: A technique of coating one metal with another, used for decorative objects (gold, silver) and in the aluminum industry.
- Malleable Material: A material that can be shaped or formed easily.
Objective 9: Movement
- Types of Movement:
- By Reference: Absolute, relative.
- By Trajectory: Rectilinear, curvilinear (elliptic, parabolic, circular).
- By Nature: Uniform, varied.
- Elements of Movement: Displacement, time, distance.
- Other Movements: Wave, oscillatory, uniform circular.
Objective 10: Alfred Wegener’s Theory of Continental Drift
Alfred Wegener was a German scientist who developed the theory of continental drift. He proposed that the continents were once joined together and have since drifted apart.
- Earthquakes: Ground shaking that occurs due to the movement of tectonic plates and the release of energy.
- Tsunamis: A wave or series of waves that are produced in a body of water, often caused by earthquakes.
Objective 11: Factors Determining Climate and Soil
Factors determining climate include altitude, latitude, relief, vegetation, and soil.
Soil is the surface layer of the Earth’s crust. The lithosphere is where plant roots develop. Soils are formed by the weathering of rocks.
- Physical Weathering: Caused by sunlight, sudden temperature changes, and precipitation.
- Chemical Weathering: Water penetrates the rock, dissolving chemical elements and weakening it.
- Biological Weathering: Caused by living components.
Soil Profile: The sequence of layers from A to C.
- Soil Classification:
- Residual Soils: Form in the same spot where the rock breaks down.
- Sedimentary Soils: Formed by the dragging of rock pieces to another site.
- By Composition:
- Sandy: Have a large amount of sand.
- Clay: Have a lot of clay, often reddish in color.
- Calcareous: Contain calcium salts.
- Loamy or Silty: Have a balanced blend of sand, clay, and silt; good for agriculture.
- Humus-rich: Rich in organic matter.
Objective 13: Plant Processes
Absorption: The intake of dissolved salts, principally by the roots.
Circulation: The transport of substances from the roots to the leaves and from the leaves to the whole plant.
Transpiration: The elimination of excess water.
Photosynthesis: A complex process during which plants synthesize their own organic substances.
Assimilation: Proper nutrition, involving the incorporation of elements and compounds.
Excretion: The expulsion of substances produced by the protoplasm.
- Xylem: Vascular tissue that provides mechanical support to the plant and carries water and minerals.
- Phloem: Tissue that allows the transport of elaborated sap.
- Chloroplast: Organelles of plant cells where photosynthesis takes place. They contain chlorophyll and are 3 to 5 microns in size.
- Chlorophyll: The green pigment found in chloroplasts that absorbs sunlight and converts light energy into chemical energy.
Photosynthesis and Respiration
Photosynthesis essentially consists of capturing the energy of sunlight and converting it into chemical energy. Respiration is a function performed by all living organisms (protists, plants, and animals). It takes place in the mitochondria and involves oxidation, the uptake of oxygen to extract energy from organic compounds.
Respiration is common to all living organisms, while photosynthesis is only performed by organisms containing chlorophyll.
Phases of Photosynthesis
- Light-dependent Phase: Occurs during the daytime. Water and minerals are absorbed by the root, travel through the xylem to the leaves, and oxygen is released into the environment.
- Light-independent Phase (Dark Phase): Occurs overnight. Hydrogen remaining in the leaf combines with minerals, and a series of chemical reactions produce food (sugars and carbohydrates). These foods accumulate in the leaves, stems, roots, seeds, and flowers of the plant. This process is unique to plants.
The formula for photosynthesis is:
