Select the correct statement about the function of myocardial cells.
A) The influx of potassium ions from extracellular sources is the initiating event in cardiac muscle contraction.
B) The entire heart contracts as a unit or it does not contract at all.
C) The refractory period in skeletal muscle is much longer than that in cardiac muscle.
D) Each cardiac muscle cell is innervated by a sympathetic nerve ending so that the nervous system can increase heart rate.

The model illustrates a process by which a substance is taken up by a cell

Drag each tile to the correct box. match the given symbol or molecular formula to the term that best describes it. element -organic compound -inorganic elemental molecule -inorganic compound -answers given: so2, k, ci2, c6h6

Use this dichotomous key for insect identification to identify the insect shown. 1. a. insect has one pair of wings. order diptera b. insect has two pairs of wings. go to #2 2. a. front wings thicker in texture than hind wings go to #3. b. front and hind wings are same texture throughout. go to #4 3. a. front wings are short order dermaptera b. front wings cover entire abdomen order coleoptera 4. a. wings with scale on all parts of their area. order lepidoptera b. wings without scales go to #5. 5. a. hind wings smaller than front wings. order ephemeroptera b. front and hind wings nearly equal in size. order odonata the insect pictured is in the order diptera. ephemeroptera. coleoptera. odonata.