Molting is controlled by a hormone.是什么意思？

Molting is controlled by a hormone.

蜕皮是由一种激素.

molting

n. 蜕皮；v. 换羽，脱毛( molt的现在分词 )；

例句
The old cuticle is digested by molting fluid.
旧表皮被蜕皮液消化.

is

vt.& vi. 是（be的三单形式；n. 存在；

例句
Bollinger 'RD' is a rare, highly prized wine.
博林格RD香槟是一种名贵的备受推崇的葡萄酒。

controlled

adj. 受约束的，克制的；v. 控制( control的过去式和过去分词 )，管理，限制，克制；

例句
Exchange is largely controlled by big banks.
货币兑换业务主要由大银行控制。

by

prep. 在…旁边，表示方式，由于，经过；adv. 经过，表示保留或保存时用，短暂拜访；

例句
...expensive make-up that we saw being advertised by a beautiful model...
我们所见的由一位漂亮模特代言的昂贵化妆品

hormone

n. 荷尔蒙，激素；

例句
Vitamin C has many roles to play in weight control. Firstly, it is needed for hormone production.
维生素C在控制体重方面扮演着多重角色。首先，荷尔蒙的生成有赖于它。