Certain fossils, called index fossils, help geologists match rock layers. To be useful as an index fossil, a fossil must be widely distributed and represent a type of organism that existed for a brief time period. Index fossils are useful because they tell the relative ages of the rock layers in which they occur.
Answer:
Nucleic acids
Explanation:
Nucleic acids are the biopolymers, or small biomolecules, essential to all known forms of life. The term nucleic acid is the overall name for DNA and RNA.
Answer:
C. the medulla oblongata, which is in contact with cerebrospinal fluid, monitors pH and uses this measure to control breathing.
Explanation:
The central chemoreceptors are located near the medulla inside the blood-brain barrier. When CO2 in cerebrospinal fluid increases, pH of the fluid lower (because CO2 becomes hydrated to carbonic acid). Change in pH stimulates the central chemoreceptors to activate respiratory centers which will increase the respiratory rate and depth of breathing.
Answer:
<h2>
<em>photosynthesis</em></h2>
<em>in</em><em> </em><em>this</em><em> </em><em>process plants use carbon dioxide</em><em />
