Answer:
Proximal tubule is involved in reabsorption from blood to filtrate while Distall tubule is also involed in secretion from blood to filtrate.
Explanation:
Proximal Tubule;
It reabsorbs the important nutrients such as water, sodium, potassium, calcium, glucose, aminoacid etc. from the filtrate and send them back into the bloodstream.
Distal tubule;
Although distal tubule is involved in reabsorption of nutrients such as calcium, sodium chloride but it is also in secretion of blood wastes such as drugs into the filtrate. It also help in maintaining the pH of blood by secreting the protons into filtrate and absorbing the bicarbonate ions.
<span>1.
</span>They act as activators of transcription. This is
through increasing the affinity of the RNA polymerase on the promoter
<span>2.
</span>They could act as repressors. This way, when
they bind to their active sites, they
repress the binding of the RNA polymerase on the promoter
<span>3.
</span> Transcription factors at one site could affect transcription of genes on another site on the
DNA. The flexibility of the DNA (by forming loops) allows for this phenomenon.
Your answer is <span>3.
Iron</span>