PLEASE HELP!!

Describe an example of how gene expression is regulated.

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Common symptoms of an iron-defiency anemia include muscle weakness shortness of breath and lightheadedness why does iron deficiency causes these symptoms

What do isotopes of uranium have the same number of? what do they have a different number of? a) same number of protons; different number of electrons b) same number of protons; different number of neutrons c) same number of electrons; different number of protons d) same number of neutrons; different number of protons