So what is active transport for?

那么主动运输是用来干什么的呢？

Watch part 2 to learn about active transport.

观看第 2 集，了解主动运输吧。

All of these things require the movement of substances by either diffusion, osmosis, or active transport.

所有这些都需要物质通过扩散、渗透或主动运输的方式进行运动。

So not having active transport, but rather passive transport.

所以没有主动运输, 而是被动运输。

Cells which carry out a lot of active transport often have lots of mitochondria to give them the energy they need.

进行大量主动运输的细胞通常有大量的线粒体来提供它们所需的能量。

So we know all about the movement of gases and water, but what is active transport for?

所以我们都知道气体和水的运动，但什么是主动运输呢？

Growth and repair of cells, muscle contraction, protein synthesis, sending nerve impulses, absorbing molecules, and active transport, to name just a few.

细胞的生长和修复、肌肉收缩、蛋白质合成、发送神经冲动、吸收分子和主动运输等等。

The tissue lining your small intestines, for instance, is what allows you to absorb nutrients through diffusion and active transport, so that's pretty important.

比如说，小肠里的组织让你能够通过扩散和主动运输吸收营养，所以这很重要。

So from these two parts, you should know how cells take in substances and get rid of waste by diffusion osmosis and active transport.

所以从这两个部分，你应该知道细胞是如何通过扩散渗透和主动运输来吸收物质和排出废物的。

And digestion allows for the absorption of those nutrients as they pass from the small intestine into the blood, by both active and passive transport.

消化允许吸收这些营养物质，当它们从小肠进入血液时，通过主动和被动运输。

Just think of a slide: you don't need any energy to go from high to low; it's easy, whereas active transport is the opposite.

你不需要任何能量从高到低；这很容易，而主动运输恰恰相反。

Depending upon what is being exchanged and which direction along the concentration gradient things are traveling will determine whether diffusion osmosis or active transport will be used.

根据交换的东西和沿着浓度梯度的方向，物体将决定是采用扩散渗透还是主动运输。

See the difference between diffusion, no energy is needed because the molecules can just slide down the concentration gradient, whereas in active transport, they are joining the crowd and so more effort is needed, hence the ATP.

看看与扩散之间的区别，扩散不需要能量，因为分子可以沿着浓度梯度下滑，而在主动运输中，它们聚集在一起，因此需要更多的努力，需要 ATP。