The opening to the tracheal system (respiratory system) in insects is the

A. spiracle.
B. trachea.
C. alveolus.
D. bronchus.
E. stomata.


A. spiracle.

Biology & Microbiology

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A protein on a cell surface that binds to a signaling molecule is an example of which of the following elements of cellular communication?

A. a signaling cell B. a signaling molecule C. a receptor molecule D. a responding cell E. None of these choices are correct.

Biology & Microbiology

In which of the following ways does cardiac muscle differ from skeletal muscle?

A. Cardiac muscle is striated and skeletal muscle is not. B. Cardiac muscle surrounds hollow tubes; skeletal muscle attaches to skin. C. Cardiac muscle cells are electrically connected; skeletal muscle cells are not. D. Cardiac muscle is under voluntary control; skeletal muscle is under involuntary control. E. A group of cardiac muscle cells forms an organ; a group of skeletal muscle cells forms a tissue.

Biology & Microbiology

The rate which velocity changes with time

What will be an ideal response?

Biology & Microbiology

What is not a trace mineral

What will be an ideal response?

Biology & Microbiology