Fungi: mushrooms, moulds and yeasts
Aprende
The mushrooms in the forest, the mould on bread and Ellie’s yeast seem very different, but they are all fungi. Fungi form a kingdom of their own: they are not plants or animals.
Three kinds of fungi Plants have chlorophyll, a green substance with which they use light to carry out photosynthesis. Fungi have no chlorophyll and do not carry out photosynthesis. They do not make their food: they take it from the remains of other living things or from the food they grow on.
fungus plant animal chlorophyll no yes no photosynthesis no yes no food takes it from remains makes it eats other living things cells one or many many many Fungus, plant and animal What we call a mushroom is only the part of the fungus that comes out above the ground. It releases spores, tiny grains from which new fungi can grow. Most of the fungus is the mycelium: a network of very fine threads, hidden under the ground or inside a trunk.
The mushroom and the mycelium Mould is a fungus of very fine threads that grows on bread, fruit and other food, especially when it is damp and warm. Its threads go into the food, beyond the patch that can be seen. That is why mouldy bread is thrown away whole, without cutting off “the green part”, and it is not sniffed up close.
Yeast is a fungus with a single cell. In bread dough it feeds on the sugar and releases a gas. The gas forms bubbles and the dough rises. This change is called fermentation.
Yeast makes the dough rise Some mushrooms are poisonous and cannot be recognised by their appearance. Never pick or eat a wild mushroom: only an expert can say which kind it is.
Worked examples
Ejemplo 1
Gus sees a mushroom with very pretty colours in the forest and wants to take it to Ellie for dinner. What should he do?
- You cannot tell from the appearance, the smell or the taste whether a mushroom is poisonous.
- Some poisonous mushrooms look very much like the ones that are eaten.
- Only a mushroom expert can say, with the mushroom in front of them.
Gus should leave the mushroom where it is, not taste it and tell an adult.
¡Ojo! Many children think that a pretty mushroom, or one that smells good, cannot do any harm.
Ejemplo 2
Ellie mixes flour, water, sugar and yeast, and leaves the dough in a warm place. After an hour, the dough has risen. Why?
- Yeast is a fungus with a single cell, and it is alive.
- It feeds on the sugar in the dough and releases a gas.
- The gas forms bubbles inside the dough and makes it swell.
The dough rises because of the gas that the yeast releases.
¡Ojo! Many children think that yeast is a lifeless powder, and that the dough rises only because of the heat.
Ejemplo 3
Julie finds a loaf of sliced bread with a green patch in one corner and says: “I will cut off the corner and eat the rest”. Is that a good idea?
- The green patch is mould, a fungus with very fine threads.
- The threads go into the bread, beyond what can be seen.
- Cutting off the corner does not remove the threads from the rest of the bread.
No: mouldy bread is thrown away whole.
¡Ojo! Many children think it is enough to remove the part where the mould can be seen.
Un reto para pensar
With the help of an adult, put a piece of damp bread in a plastic bag and a piece of dry bread in another bag. Close both well and leave them in a warm place. Look every day at how much mould grows, without opening the bags. When you finish, throw them away closed and wash your hands.
Practica
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