TLS Online TPP Program

#Question id: 7137


Which of the following correctly describes the sequence of events by which the position of limbs along the antero-posterior axis of vertebrates is specified?

#Unit 5. Developmental Biology
  1. Hox gene expression in the mesoderm activates Wnt signaling, which turns on FGF expression and formation of the limb bud.
  2. Wnt signaling activates Hox gene expression, which turns on FGF expression and formation of the limb bud.
  3. FGF expression in the mesoderm activates Wnt signaling, which turns on Hox gene expression and formation of the limb bud.
  4. Hox gene expression in the mesoderm activates FGF signaling, which turns on Wnt expression and formation of the limb bud.
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TLS Online TPP Program

#Question id: 11211

#Unit 7. System Physiology – Animal

The following steps refer to various stages in transmission at a chemical synapse.


1. Neurotransmitter binds with receptors associated with the postsynaptic membrane.


2. Calcium ions rush into neuron's cytoplasm.


3. An action potential depolarizes the membrane of the presynaptic axon terminal.


4. The ligand-gated ion channels open.


5. The synaptic vesicles release neurotransmitter into the synaptic cleft.


Which sequence of events is correct?

TLS Online TPP Program

#Question id: 11212

#Unit 7. System Physiology – Animal

The activity of acetylcholine in a synapse is terminated by its ________.

TLS Online TPP Program

#Question id: 11213

#Unit 7. System Physiology – Animal

An example of ligand-gated ion channels is ________.

TLS Online TPP Program

#Question id: 11214

#Unit 7. System Physiology – Animal

Neurotransmitters categorized as inhibitory are expected to ________.

TLS Online TPP Program

#Question id: 11215

#Unit 7. System Physiology – Animal

If excitatory postsynaptic potentials (EPSPs) are produced nearly simultaneously through two different synapses on the same postsynaptic neuron, the EPSPs can also add together creating ________.

TLS Online TPP Program

#Question id: 11216

#Unit 7. System Physiology – Animal

When two excitatory postsynaptic potentials (EPSPs) occur at a single synapse so rapidly in succession that the postsynaptic neuron's membrane potential has not returned to the resting potential before the second EPSP arrives, the EPSPs add together producing ________.