The circulatory system moves blood in our bodies. The blood can move oxygen and nutrients to our muscles and limbs. The heartbeat pushes the blood, and the blood cells carry glucose.
They are pretty much the cause and effect. The independent variable that is being changed in the experiment, so it is the cause. The dependant variable is the result of change the independant variable, so the effect.
Answer :
(a) The overall equation is:

(b) The intermediates are :

Explanation :
<u>Part (a) :</u>
(1)
(fast)
(2)
(slow)
(3)
(fast)
By adding the three equations and cancelling the common terms on both side, we will get the overall equation.

<u>Part (b) :</u>
Intermediates are generated and consumed in the mechanism and do not include in the overall equation.
Since, intermediates will not include in the overall mechanism.
The intermediates are :

Explanation:
If the density of the object is more than that of water, it will sink. Otherwise it will float. The density of water is 1 g/mL.
Substance 1,
Mass, m = 450 g, Volume, V = 90 mL
Density = mass/volume
So,

It will sink.
Substance 2,
Mass, m = 35 g, Volume, V = 70 mL
Density = mass/volume
So,

It will float.
Substance 3,
Mass, m = 24 g, Volume, V = 12 mL
Density = mass/volume
So,

It will sink.