Question

1. Is obtaining O2 harder in water than in air?

2. How do neurotransmitters communicate signals?

Answer 1

Answer for Question number 1: Yes, obtaining O2 is harder in water than in air.

Explanation:

• It is harder to obtain oxygen from water. One of the main reasons is the scarcity of oxygen (in gaseous form i.e. O2) in the water compared to the availability of oxygen in the air( air has about 20 times more oxygen than the oxygen level in water).
• The organism living in water can't take up the oxygen which is complexed with the hydrogen atoms (forming H2O). They rely completely on the dissolved oxygen (in water) which is in very low amount. To utilize this limited supply of oxygen they have adapted various features(gills), that enables them to have more surface area to obtain the oxygen for breathing.
• Whereas the terrestrial organisms don't have those adaptations(larger surface area to absorb oxygen) so they can't utilize oxygen dissolved in water. They rely completely on oxygen in the air(which is much easier to obtain).

Answer for Question number 2:

• Neurotransmitters are a group of chemicals which are released by certain neurones upon receiving signals via the mode of an action potential.
• The neurotransmitters are released by the pre-synaptic neurones and they move across the synapse and reaches the post-synaptic neuron and binds to the respective receptor and convey the signal.
• This is how a neurotransmitter communicates signals in the nervous system.