Answer:
I would say chordates. (Not absolutely sure so double check)
Explanation:
Chordates have a dorsal nerve cord, which is super close to a spinal cord. (Which vertebrates have.)
Answer:
B. Multipotent cells
Explanation:
Multipotent stem cells are the one that develops from pluripotent stem cells during embryonic development. The multipotent stem cells are the stem cells which have specific functions. These cells develop into specific cell types to replace the older cells.
For example, keratinocytes are the multipotent cells of the skin that produce new skin cells. Spermatogonia are the multipotent cells present in testes so that they can form sperms.
The skin is composed of thin membranous tissue that is quite permeable to water and contains a large network of blood vessels. The thin membranous skin is allows the respiratory gases to readily diffuse directly down their gradients between the blood vessels and the surroundings. When the frog is out of the water, mucus glands in the skin keep the frog moist, which helps absorb dissolved oxygen from the air.
A frog may also breathe much like a human, by taking air in through their nostrils and down into their lungs. The mechanism of taking air into the lungs is however sligthly different than in humans. Frogs do not have ribs nor a diaphragm, which in humans helps serve in expand the chest and thereby decreasing the pressure in the lungs allowing outside air to flow in.
In order to draw air into its mouth the frog lowers the floor of its mouth, which causes the throat to expand. Then the nostrils open allowing air to enter the enlarged mouth. The nostrils then close and the air in the mouth is forced into the lungs by contraction of the floor of the mouth. To elimate the carbon dioxide in the lungs the floor of the mouth moves down, drawing the air out of the lungs and into the mouth. Finally the nostrils are opened and the floor of the mouth moved up pushing the air out of the nostrils.
Frogs also have a respiratory surface on the lining of their mouth on which gas exchange takes place readily. While at rest, this process is their predominate form of breathing, only fills the lungs occasionally. This is because the lungs, which only adults have, are poorly developed.
Answer: summation
Explanation:
The process which determine if an action potential will be generated or not depends on the combined effects of the signal inputs from multiple sources of synapse or from the repeated signals from the same synapse.
If the input signals reach the threshold voltage, action potential will be generated. (all –or –none principle).Therefore, this process is a determinant of the likelihood of action potential generation and it is called summation.
Summation is the ability to integrate multiple PSPs at multiple synapses.it is the process that determine if an action potential will be generated by combined effects of inhibitory or excitatory signals.
Based on the pathways and voulme of applied stimuli in the presynaptic neuron;
The signals can be temporal summation ( consecutive signals produced from the same synapse)where action potential of high frequency in the PSN generated action potential in the post synaptic neuron, which summate with one another. Or Spatial where signals inputs are from multiple presynaptic cells.
... ....... .... ...... ........... ....
