Which of the following structures is directly involved in the passage of electrical signals between cells as, for example, in the vertebrate heart?
a) anchoring junctions
b) tight junctions
c) chemical synapses
d) gap junctions

The correct answer is d) gap junctions

Explanation:

Animals have gap junction in many places in their body like in cardiac muscles, nerves, epithelial cells, smooth muscles. It connects cell to cell through cytoplasm and helps in transferring of many molecules and electric signals between these cells.

Vertebrate heart is made up of mainly muscle tissue in which electric signals are transferred through these gap junctions throughout the heart.

These gap junction plays important role in contraction of all the muscle cells in the heart together which is an important process called systole.

Therefore, the correct answer is d) gap junctions.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

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