The characteristics of living things
An earthworm, an oak tree and a mushroom look nothing alike on the outside. And yet all three are living things. What do an earthworm and a tree have in common that a stone does not?
Made of cells and of the same elements
If you look at a drop of stagnant water, a piece of onion and a scraping from the inside of your cheek under a microscope, in all three cases you discover tiny, independent little compartments: what basic unit do such different living things share?
List the four most abundant bioelements in living things and explain what it means that all living things share a common chemical composition.
List the four most abundant bioelements in living things and explain what it means that all living things share a common chemical composition.
An earthworm, an oak tree, and a mushroom have very different sizes and shapes. State at least three shared characteristics that prove all three are living things.
An earthworm, an oak tree, and a mushroom have very different sizes and shapes. State at least three shared characteristics that prove all three are living things.
Water is the most abundant substance in most living things. Explain what this statement means and give two examples that show it (for example, what approximate…
Water is the most abundant substance in most living things. Explain what this statement means and give two examples that show it (for example, what approximate percentage of the human body is water, or what happens to a lettuce when it dehydrates).
The three vital functions
Look at the diagram: a living thing carries out three life processes, labeled with letters A, B, and C. Name the life process represented by each letter, briefly…
Look at the diagram: a living thing carries out three life processes, labeled with letters A, B, and C. Name the life process represented by each letter, briefly describe what it involves, and give an example of an animal or plant carrying it out.
State which life process each of these belongs to: a plant makes its food using light, a rabbit flees when it hears a fox, a pair of storks raises their chicks, and a…
State which life process each of these belongs to: a plant makes its food using light, a rabbit flees when it hears a fox, a pair of storks raises their chicks, and a sunflower turns its flower towards the Sun.
A cat that hears a noise turns its ears towards it and freezes. Identify the stimulus and the response, state which life process it is carrying out, and explain why this…
A cat that hears a noise turns its ears towards it and freezes. Identify the stimulus and the response, state which life process it is carrying out, and explain why this is useful to the cat.
Is it a living thing or does it just look like one?
A flame consumes wood to grow, flickers in the wind and gives off sparks that can set dry leaves alight: why does science not consider it a living thing if it seems to feed, react and multiply?
Fire "grows", moves, "feeds" on firewood, and can "reproduce" in sparks that light another fire. Explain why, even so, nobody considers it a living thing.
Fire "grows", moves, "feeds" on firewood, and can "reproduce" in sparks that light another fire. Explain why, even so, nobody considers it a living thing.
A salt crystal "grows" if more salt is added to its solution. Explain why this growth does not make the crystal a living thing, pointing out at least two differences…
A salt crystal "grows" if more salt is added to its solution. Explain why this growth does not make the crystal a living thing, pointing out at least two differences compared to the growth of a plant.
A robot vacuum cleaner moves around the house, avoids obstacles, and returns to its dock by itself to recharge its battery. Check each characteristic of living things…
A robot vacuum cleaner moves around the house, avoids obstacles, and returns to its dock by itself to recharge its battery. Check each characteristic of living things one by one and conclude, providing arguments, whether the robot could be considered alive.
Back to the beginning: The earthworm and the tree share being made of cells, having a chemical composition based on C, H, O, N and water, and carrying out the functions of nutrition, relation and reproduction; the stone has no cells and no vital functions at all.