Essential questions: What is the basic unit of life?
Objectives: Understand what is meant by cell theory. Know exceptions to cell theory.
Cell theory states that living organisms are made from cells. This establishes cells as the building blocks of living organisms. The most simple organisms are only made from one cell, such as Protists (in the kingdom Protoctista).
and generate their own energy.
Life is an emergent property (it emerges from the interactions of their cellular components, as something extra to them).
Can you think of other examples of emergent properties?
The implicit assumption of cell theory is that nothing smaller than a cell can survive eg. a cell membrane cannot live on it’s own.
Movement: to transport oneself from place to place.
it is also assumed that cells come from pre-existing cells. Cells cannot spontaneously appear from nothing (it was once thought that this was possible, it was called the theory of spontaneous generation).
The cell is the basic unit of life (nothing smaller than a cell is alive).
TASK: PLASTICINE ALIEN: You have five minutes as a group to create a model of an alien made from plasticine. You need to explain the basic natural history of the alien, give it a name, and then explain how it carries out the seven characteristics of life.
Task: Investigating two single celled organisms, Paramecium and Scenedesmus.
Giant algae (A). Several species of Giant algae exist eg. Caleurpa. which seem to have only one nucleus, and so seem to be made of one giant cell. They can be as long as 100mm.
Understanding relative sizes: Follow this link to compare the relative sizes of cells / organelles in the general framework of things.
You must know how to prepare a wet slide of plant and animal tissue, focus on the relevant cells, estimate cell size and make a clearly labelled tissue drawing ( a tissue drawing is where no individual cells are drawn). Please see the lab skills webpage of MrHorrocks.com for more details.