Question

16 a test organism develops a genetic mutation that causes neurons to develop without synaptic knobs. how will this impact neuronal function? multiple choice action potentials will not travel down the axon nearly as rapidly. the dendrites of the postsynaptic neurons will have no means to attach to presynaptic axons. signal transduction down the axon will be interrupted, so the signal will not jump the synapse and reach the postsynaptic neuron. no neurotransmitters will be stored or released into the synapse to signal the postsynaptic neuron.

Explanation:

Synaptic knobs (also known as axon terminals) are responsible for storing and releasing neurotransmitters. Neurotransmitters are chemical messengers that cross the synaptic cleft to signal the postsynaptic neuron. Without synaptic knobs, there is no structure to store and release these neurotransmitters.
Action potentials travel down the axon based on the properties of the axon membrane (like ion channels), not directly dependent on synaptic knobs for their speed along the axon. Dendrites of postsynaptic neurons do not "attach" to presynaptic axons in the way described in the second option. Signal transduction down the axon (action potential propagation) is not interrupted by the lack of synaptic knobs; the problem is at the synapse (release of neurotransmitters), not along the axon's length for action - potential propagation.

Answer:

No neurotransmitters will be stored or released into the synapse to signal the postsynaptic neuron.