(2a)
(i)
Activation of chlorophyll: This is the process by which chlorophyll molecules in the chloroplasts absorb light energy and transfer it to other molecules in the photosystem. This energy is used to initiate the electron transport chain and the synthesis of ATP and NADPH
(ii) *Photolysis of water:* This is the process by which water molecules are split into hydrogen ions and oxygen atoms by the action of light and a special enzyme called water-splitting complex. The hydrogen ions are used to reduce NADP+ to NADPH, and the oxygen atoms are released as a by-product of photosynthesis.
(iii)
Formation of ATP: This is the process by which the energy from the electron transport chain is used to pump hydrogen ions across the thylakoid membrane, creating a proton gradient. The hydrogen ions then flow back through a protein called ATP synthase, which uses their kinetic energy to produce ATP from ADP and phosphate.
(3ai)
(i)Heavy metals (e.g., lead, mercury)
(ii)Industrial chemicals
(iii)Nutrient pollutants (e.g., nitrogen, phosphorus)
(iv)Pathogens (e.g., bacteria, viruses)
(3aii)
(i)Particulate matter (PM)
(ii)Nitrogen dioxide (NO2)
(3bi)
(i)Respiratory problems (e.g., asthma, bronchitis)
(ii)Cardiovascular diseases
(iii)Damage to the ozone layer
(iv)Adverse effects on wildlife and ecosystems
(3bii)
(i)Emissions from vehicles (e.g., cars, trucks)
(ii)Industrial activities and emissions
(iii)Agricultural practices (e.g., burning of crop residues)
(iv)Deforestation and biomass burning
(3c)
(i)Water pollution:
(i)Implementing stricter regulations and enforcement for industrial discharge and wastewater treatment
(ii)Promoting sustainable agricultural practices to minimize chemical runoff into water bodies
(ii) Industrial pollution:
(i) Investing in cleaner production technologies and processes to reduce emissions and waste generation
(ii) Implementing recycling and reuse programs to minimize the generation of industrial waste and pollutants.
(3d)
Reducing refers to the process of adding electrons or hydrogen ions to a molecule, resulting in a decrease in the oxidation state of the molecule.
(4a) Population dominance refers to the condition where one or a few species within an ecosystem have a significantly higher abundance or biomass compared to others, exerting a substantial influence on the ecosystem dynamics.
(4b)
(4bi) Primary production in an ecosystem refers to the synthesis of organic compounds by autotrophic organisms, mainly plants, through photosynthesis.
(4bii) The primary source of energy in an ecosystem is sunlight, which is captured by autotrophic organisms during photosynthesis and then transferred through the food web.
(4biii)
PICK ANY THREE
(1) Photosynthesis: Carbon is a key element in the formation of organic compounds during photosynthesis.
(2) Respiration: Carbon is released during the process of respiration, providing energy for living organisms.
(3) Biomolecules: Carbon is a fundamental building block of essential biomolecules such as carbohydrates, proteins, lipids, and nucleic acids.
(4) Carbon Cycle: Carbon plays a crucial role in the global carbon cycle, cycling between the atmosphere, oceans, soil, and living organisms.
(5) Climate Regulation: Carbon dioxide, a form of carbon, contributes to the greenhouse effect, regulating Earth’s temperature and climate.
(5)
(a) Population dominance is a concept that describes the relative abundance and influence of a species or a group of species in an ecosystem. A dominant species is one that has a large population size, a high biomass, or a strong impact on the community structure and function. A dominant group is a set of species that share similar traits and occupy similar niches in an ecosystem.
(bi) Primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide by living organisms, such as plants, algae, and some bacteria. Primary production is the basis of the food web and the source of energy and biomass for all other organisms in an ecosystem.
(bii) The primary source of energy for almost every ecosystem on Earth is the sun. The sun provides solar radiation that can be captured and converted into chemical energy by photosynthetic organisms, such as plants and phytoplankton. This energy is then transferred to other organisms through the food chain.
(biii)
(1)Carbon is a major component of all organic molecules, which are essential for the structure and function of living cells. Carbon is also involved in many biochemical reactions, such as photosynthesis and respiration.
(2)Carbon is part of the carbon cycle, which regulates the exchange of carbon between the atmosphere, the land, the ocean, and the biosphere. The carbon cycle affects the global climate by influencing the concentration of carbon dioxide, a greenhouse gas that traps heat in the atmosphere.
(3) Carbon is a resource that can be used by humans for various purposes, such as energy production, agriculture, industry, and medicine. However, human activities can also alter the carbon cycle and cause environmental problems, such as global warming, ocean acidification, and deforestation.
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