These are all parasites, organisms that live on or inside another host organism, which they harm and sometimes even kill.

牠们全是寄生虫，能在寄宿於另一个生物体内或外表，并能够伤害甚至使宿主死亡。

Because if there were too many parasites, they would kill off the host organisms they live on.

因为如果寄生虫太多， 它们会杀死它们赖以生存的宿主生物。

And what all of these ecosystems have in common is that they all host organisms that are not reliant on oxygen, so phosphine can't hurt them.

这些生态系统的共同点是它们都是不依赖氧气的宿主，所以磷化氢不能伤害它们分毫。

Propagation of the host organism containing the recombinant DNA forms a set of genetically identical organisms, or a clone. This process is hence known as DNA cloning.

宿主和载体。