请教四个英语句子

请教四个英语句子
一：killing a small but significant number of cells directly.
其中significant number of怎么翻译呢?
二：Agricultural research has developed much faster on plants than animals.And there is insufficient reason to expect that if species patents on plants are upheld,the practice of granting such patents will be restricted to them.It seems from developments so far that the blitzkrieg is inching its way to higher life forms.
其中blitzkrieg原意是闪电战,这里指什么?
三：Broadly worded patent rights (as in the case of cotton or soybean),or the taking out of a large n umber of patents effectively suppress competition through the threat of infringement suits.
taking out of如何翻译?
四：Utility patents also prohibit farmers from the common practice of saving and using seeds from previous crops or from breeding animals,as well as restricting research exemptions.
restricting往上接哪个from?