4.1 - Cell Communication Basics

Which statement best defines a ligand in cellular communication?

• A receptor protein on target cells

• An ion channel forming gap junctions

• A membrane carbohydrate for recognition

• A signaling molecule that binds receptors

Fill in the blank: In order for a cell to respond to a signal, the receiving cell must have the correct type of (a)   .

Identify the primary difference between paracrine and endocrine signaling.

• Receptor structure differs

• Signal processing steps differ

• Target cell distance differs

• Ligand chemical class differs

Which communication type relies on direct membrane contact between adjacent cells?

• Autocrine signaling

• Paracrine signaling

• Endocrine signaling

• Juxtacrine signaling

Explain why a cell lacking the appropriate receptor does not respond to a circulating hormone.

Which example best illustrates autocrine signaling?

• Virus‑infected cell signaling apoptosis

• Insulin released into blood

• Neurotransmitter across synapse

• Growth factor affecting neighbors

Gap junctions in animal cells primarily facilitate which function in communication?

• Long‑distance hormone delivery

• Exchange of small signaling molecules

• Presenting antigens to lymphocytes

• Transporting neurotransmitters in synapses

Compare synaptic signaling to paracrine signaling in terms of transmission mechanism.

Which statement correctly describes endocrine signaling?

• Signals diffuse short distances locally

• Signals pass through gap junction channels

• Signals require cell‑to‑cell membrane contact

• Signals travel via bloodstream to distant targets

Fill in the blank: Plant cells communicate directly through structures called (a)   that connect adjacent cell walls and membranes.