Which of the following acts as a secondary messenger during metabolism?

Which of the following is an example of negative feedback control in humans?

Which row in the chart contains the words that best complete this statement? The $(I)$ glands produce $(II)$, which are transported by the $(III)$ system.

Row	$I, II, III$
$A$. digestive, hormones, circulatory
$B$. endocrine, enzymes, lymphatic
$C$. endocrine, hormones, circulatory
$D$. digestive, enzymes, lymphatic

Which of the following glands secrete peptide hormones?

Which of the following is not a secondary messenger?

Which one of the following pairs of hormones are the examples of those that can easily pass through the cell membrane of the target cell and bind to a receptor inside it (mostly in the nucleus)?