Question

bionb exam 3 - chapters 10 and 11 nervous syst
a test organism develops a genetic mutation that causes neurons to develop without synaptic knobs. how will this impact neuronal function?
multiple choice
the dendrites of the postsynaptic neurons will have no means to attach to presynaptic axons.
no neurotransmitters will be stored or released into the synapse to signal the postsynaptic neuron.
action potentials will not travel down the axon nearly as rapidly.
signal transmission down the axon will be interrupted, so the signal will not jump the synapse and reach the postsynaptic...

Explanation:

Synaptic knobs (presynaptic terminals) are where neurotransmitters are stored and released into the synapse to transmit signals to postsynaptic neurons. If neurons develop without synaptic knobs, there's no structure to store and release neurotransmitters, so no synaptic signaling (via neurotransmitters) to the postsynaptic neuron occurs. The other options are incorrect: dendrites of postsynaptic neurons attach to presynaptic axons (not related to synaptic knobs), action potentials travel down axons (synaptic knobs don't directly affect axonal action potential speed), and signal transmission across synapses relies on neurotransmitters (not "jumping" the synapse).

Answer:

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