Hialeah Gardens High School  2021-2022

3.1 Interactions
Different species of organism may live in a close relationship with one another, which is known as symbiosis. Parasitism, commensalism and mutualism are types of symbiosis, differing from one another in the degree of benefit gained by each partner.

Learning outcomes
Candidates should be able to:
3.1.1 describe the meaning of parasitism, commensalism and mutualism, and understand that they are all examples of symbiotic relationships

3.1.2 describe the parasitic relationship between copepods and marine fish

3.1.3 describe the commensal relationship between manta rays and remora fish

3.1.4 describe the mutualistic relationship between boxer crabs and anemones

3.2 Feeding relationships
Producers harness an energy source – through either photosynthesis or chemosynthesis – to convert inorganic substances to organic substances, which contain energy that becomes available to consumers. The rate at which producers transfer energy into organic substances and produce biomass is measured as productivity, and this is affected by factors such as the availability of light. Energy is lost as it passes along a food chain, and this results in a decrease in the energy content of the organisms at each trophic level.

Learning outcomes
Candidates should be able to:
3.2.1 explain the following terms in relation to feeding relationships: consumer (including primary, secondary, tertiary and quaternary), producer, herbivore, carnivore, omnivore, decomposer, predator, prey, food chain, food web, trophic level

3.2.2 represent and interpret feeding relationships in an ecosystem as food chains and food webs

3.2.3 understand that producers can be photosynthetic or chemosynthetic

3.2.4 explain that photosynthesis captures the energy of sunlight and makes some of the energy available to the food chain, and, it can be summarised by the word equation carbon dioxide + water light /chlorophyll
glucose + oxygen (further details of photosynthesis and balanced chemical equations are not required at AS Level)

3.2.5 (PA) investigate the effect of light intensity on the rate of photosynthesis (use of fresh water plants is acceptable)

3.2.6 understand that some of the glucose produced by photosynthesis is used to produce biomass

3.2.7 understand that some of the glucose produced by photosynthesis is used in respiration to provide usable energy and can be summarised by the word equation glucose + oxygen ---> carbon dioxide + water
(further details of respiration and balanced chemical equations are not required at AS Level)

3.2.8 define productivity as the rate of production of biomass per unit area or volume, and explain how high primary productivity may influence food chains

3.2.9 calculate and explain the energy losses along food chains

3.2.10 draw, describe and interpret pyramids of energy, numbers and biomass, including those that incorporate parasites and periods of plankton bloom 

3.3 Nutrient cycles
Nutrients are materials that are required by organisms for an energy supply, and for growth and maintenance of body tissues. The availability of nutrients has a large effect on productivity, and therefore on the types and numbers of organisms that live in different parts of the oceans at different times.

Learning outcomes
Candidates should be able to:
3.3.1 understand that nutrient is a generic term for substances that are required by an organism for growth, repair, energy or normal metabolism

3.3.2 understand that nutrients can include gases such CO2, ions such as Mg2+, CO3 2–, PO4 3– and NO3– and organic compounds such as carbohydrates, lipids and proteins

3.3.3 state the chemical elements that make up carbohydrates, lipids and proteins

3.3.4 state that large molecules are made from smaller molecules, limited to starch and cellulose from glucose, proteins from amino acids, and lipids from fatty acids and glycerol

3.3.5 understand that some nutrients supply organisms with a source of
essential elements and these elements have important biological
roles:
• nitrogen, which is used to make proteins and DNA
• carbon, which is used to make all organic compounds
• magnesium, which is used to make chlorophyll
• calcium, which is used to make bones, shells and coral skeletons
• phosphorus, which is used to make DNA and bones
 
3.3.6 understand that some nutrients are soluble and that there is a reservoir of these nutrients dissolved in the ocean which is available to producers and consumers

3.3.7 explain the processes by which the reservoir of dissolved nutrients is replenished, including upwelling, run-off, tectonic activity, dissolving of atmospheric gases, excretion and decomposition

3.3.8 understand that the reservoir of dissolved nutrients is depleted by uptake into organisms

3.3.9 understand that the nutrients taken up by organisms in food chains can be removed by harvesting

3.3.10 explain why productivity may be limited by the availability of dissolved nutrients

3.3.11 describe the carbon cycle, limited to combustion, photosynthesis, respiration, decomposition, formation of fossil fuels, formation and weathering of rocks containing carbonate