The simplest viruses consist of _________.

Photoreceptors (rods and cones) are found in which part of the labelled image below?

What endocrine gland located in the cranial cavity is considered the “biological clock”?

Identify the muscle labelled “C” on the image below.

The structure on labelled “A” on the image below is called what?

Which of the following secretes hormones?

Identify the bone labelled “E” in the image below:

In this image, the pointer points to:

The filtering structure of the excretory system is called what?

What is the organ labelled “C” on the image below?