Sorting the living world into groups and identifying organisms with dichotomous keys, then food webs, the energy that flows through them, and what happens when a species disappears. Concept tutorials with an interactive key and food web.
Kingdoms and dichotomous keys: grouping and identifying organisms by observable features (AC9S7U01).
Scientists classify living things to identify them, to talk about them clearly (one name the whole world understands), and to see how they are related. A classification is built for a purpose, and different systems can suit different purposes.
Living things are sorted into kingdoms (animals, plants, fungi, protists and bacteria) using features you can observe, and you can justify each placement with those features.
A dichotomous key identifies an organism by a series of yes-or-no questions about features you can observe. Following each choice carefully leads to the right name; one wrong choice leads to the wrong one.
A few quick questions on what you should know about building a dichotomous key and why classification changes with new evidence. Taught in class; use this to check yourself.
Who eats whom, where the energy goes, and how a change ripples through a web (AC9S7U02).
A food web joins all the food chains in an ecosystem. Arrows point the way energy flows, from the food to the eater. Every organism is a producer, a consumer or a decomposer, and decomposers include microorganisms.
Energy enters a food web as sunlight captured by producers and flows one way along the arrows. At each step only about 10% is passed on; the rest is used for living or lost as heat. Matter is different: decomposers return it to be used again.
A biotic factor is a living part of an ecosystem. When one population changes, the effect ripples along the food web, beyond the species directly linked to it. Tracing the links lets you predict the cascade.
A few quick questions on abiotic factors, how a change spreads through a food web, and what food web models leave out. Taught in class; use this to check yourself.
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