Biology · Rung 6 of 6

Plants and fungi

A plant has no organs for moving or digesting, so nearly everything about it is about two problems: lifting water without a pump and spreading offspring without legs. Water climbs because evaporating from the leaves pulls on the whole column, and water molecules cling to one another so strongly that it does not break over a hundred metres: the one doing the work is the sun. Offspring spread by renting someone else's legs and wings; the flower pays the insect in nectar for carrying pollen and the fruit pays the bird in sugar for carrying the seed, so an apple is not food lost but food put there on purpose. And fungi are not plants: they do not photosynthesise, they digest outside their bodies and absorb, which puts them on the animal side of the tree and explains how hard an antifungal drug is.

Where this sits

Comes after
Energy & metabolism

Exercises from this rung

Generated by the app, from easiest to hardest

  1. In what way is a fungus more like you than like a plant?

    • In that it feeds on matter already made
    • In that it breathes through lungs
    • In that it moves to look for food
    • In that it has bones holding it up

    Why A fungus does not photosynthesise: it eats what others made, digesting outside its body and absorbing. That puts it on the animal side of the tree, far from plants, however much it looks like one growing. And it explains why an antifungal drug is so hard: what kills a fungus is too close to what kills you.

    easier

  2. Put a seed's journey in order.

    Answer Pollen reaches another flower's pistil, The ovule is fertilised, The seed forms inside the fruit, An animal carries the fruit off and drops the seed far away, The seed germinates where it does not compete with its mother

    Why The whole cycle is built to solve the problem of having no legs, and it solves it by renting someone else's. The flower pays the insect in nectar for carrying pollen; the fruit pays the bird in sugar for carrying the seed. An apple is not food the plant lost: it is food the plant put there on purpose.

    in between

  3. A tree has no pump. How does water climb a hundred metres?

    • The stem lifts it by opening and closing valves
    • The root pushes it upward with force
    • The sun heats it and it rises because it is lighter
    • The water evaporating from the leaves pulls up what comes behind

    Why From the top, not the bottom. As water evaporates from the leaves it pulls on the whole column, and water molecules cling to one another so strongly that the column does not break over a hundred metres. A big tree moves hundreds of litres a day this way at no cost: the one doing the work is the sun.

    harder