c. Iridium
Explanation:
The layer of clay that marks the boundary between the Mesozoic and Cenozoic is rich in iridium. Iridium is an element that is rare on the earth crust. It is found in other astronomical bodies.
- The Cenozoic/Mesozoic boundary is an extinction time zone on earth in which nearly all organisms were wiped out.
- During this period in time, scientists believed that a large bolide collided with the surface of the earth sending all lives to death.
- Meteorites are rich in iridium and during the collision, they released a significant proportion in earth materials.
- This is why iridium was observed by Walter Alvarez in significant proportion in Italy.
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Red blood cells carry oxygen from your lungs to your other organs. If you have anemia, your organs might receive less oxygen. When your brain gets less oxygen than usual, you might experience headaches.
With repeated bouts of acute pancreatitis, damage to the pancreas can occur and lead to chronic pancreatitis. Scar tissue may form in the pancreas, causing loss of function. A poorly functioning pancreas can cause digestion problems and diabetes
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<h3><u>Answer and Explanation;</u></h3>
- <u>Endosymbiotic theory</u> explains the origin of chloroplasts and mitochondria and their double membrane. Mitochondria of eukaryotes evolved from aerobic bacteria living within their host cell and the chloroplasts of eukaryotes evolved from endosymbiotic cyanobacteria.
- On the other hand according to the <u>autogenous hypothesis, </u>mitochondria and chloroplasts have evolved within the protoeukaryote cell by compartmentalizing plasmids or vesicles of DNA within a pinched off invagination of the cell membrane.
- <u>Endosymbiont theory </u>is the theory that suggests that simple prokaryotic cells were engulfed by larger prokaryotes 1.5 billion years ago.
- <u>Autogenous theory</u> is a theory that was proposed as an alternative to endosymbiont theory. proposes that eukaryotic organelles formed by infolding of the plasma membrane.
- <u>Horizontal gene transfer theory</u> is an alternative to endosymbiont and autogenous theories for the origin of complex organelles in eukaryotes.
Pneumonia is a leading cause of death.