Primary producers are organisms that?

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

Ascientist is conducting an investigation that involves water, silver, carbon dioxide, and oxygen gas which group of statements best describes all of the materials he is using in the investigation?

Milk production during breastfeeding is increased by the suckling of a newborn from his mother's nipple. this type of feedback mechanism best describes a positive or negative