Cell-to-cell communication is absolutely essential for multicellular organisms. but how do plants communicate when their cells are surrounded by cell walls? plants use for long-distance signaling, such as ethylene which promotes fruit ripening and regulates growth. a) hormones b) ions c) neurons d) phospholipids

Ans.

Cell-to-cell communication allows signalling of essential substances between the plant cells, which are surrounded by cell walls. The molecules used by plants for long-distance signalling are known as hormones, such as auxin, ethylene, and gibberelin.

These hormones are secreted by one plant cell and received by another plant cell, where it exerts it affect. Thus, the correct answer to be fill in the blank is 'option A). hormones.'

Explanation:

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.