CXC CSEC Biology

## Grouping organisms by what you can see Living things in a habitat such as a school garden, a wall or a small pond can be sorted into groups by their visible features. Plants are compared by leaf shape, the pattern of veins (**venation**), the colour and number of flower parts, and whether they are hairy or smooth. Animals are compared by the number of legs and wings, by body colour, and by whether the body is divided into **segments**. Common names are enough for this kind of grouping, so a student can sort ants, beetles, spiders and millipedes without knowing their scientific names. The steps are the same each time. 1. Observe each organism and record its features in a table. 2. Pick one clear difference (for example, six legs or eight) and split the organisms into two sets on it. 3. Split each set again on another difference, and continue until every organism is on its own. Written out as a flowchart of yes or no questions, this becomes a **key**. A key only works if every question has a clear answer that depends on a feature that can be seen, so "is it large?" is a poor question and "does it have wings?" is a good one. Drawings of each organism, with the features labelled, go beside the table. ## The five kingdoms Classification is the sorting of organisms into groups based on their shared features. Every living organism is placed in one of five **kingdoms**. | Kingdom | Cells | Nutrition | Examples | |---|---|---|---| | Plantae | eukaryotic, with cell walls and…