QVprep Biology Lessons

What is a food web?, What are trophic levels?, How are organisms broadly classified? Autotrophs, Heterotrophs

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What is a food web?: A food web is the typical ecological network. Plants capture solar energy and use it to synthesize simple sugars during photosynthesis. As plants grow, they accumulate nutrients and are eaten by herbivores, and the energy is transferred through a chain of organisms by consumption. The linear feeding pathway that moves from a basal trophic species to a top consumer is called the food chain.


What are trophic levels?: The trophic pyramid represents the biomass, usually measured as total dry-weight at each level. Plants generally have the greatest biomass. A trophic level refers to a group of organisms acquiring a considerable majority of its energy from the adjacent level nearer the abiotic source.


How are organisms broadly classified?: Organisms are broadly classified as autotrophs (or primary producers), heterotrophs (or consumers), and detritivores (or decomposers).


Autotrophs: Autotrophs are organisms that produce their own food (production is greater than respiration) by photosynthesis or chemosynthesis.


Heterotrophs: Heterotrophs are organisms that must feed on others for nourishment and energy (respiration exceeds production). Heterotrophs can be further sub-divided into different functional groups, including primary consumers or herbivores, secondary consumers or carnivores and tertiary consumers that feed on herbivores and carnivores.


Omnivores: Omnivores do not fit neatly into a functional category because they eat both plant and animal tissues.