In other words, how did phototropism come to be?

换句话说，趋性是如何形成？

The two plant ones we'll talking about are phototropism and then photoperiodism.

我们讨论两种植物行为是趋性和周期性。

And two big things that you should understand about plants are phototropism.

关于植物你应该理解两个念之一是向性。

And so let's start with phototropism.

让我们从趋性开始讲起。

Let's start by talking about phototropism.

让我们先来谈谈向性。

Negative phototropism would be growing in the other direction.

负向性就是朝相反方向生长。

And so immediately when you plant a seed, the roots are going to show negative phototropism.

所以当你种下一颗种子时，根部会立即表现出负向性。

Auxin will always move away from the light in positive phototropism.

在正向性中，生长素总是会远离线移动。