Answer:
The "Cambrian Explosion" refers to the sudden appearance in the fossil record of complex animals with mineralized skeletal remains. It may represent the most important evolutionary event in the history of life on Earth.
Explanation:
Answer: A) Organisms have cells with different shapes and functions.
Explanation: The cell theory explains that all organisms and plants are made of a basic structure or units, cells.
Answer:
Blood vessels constrict
Explanation:
On seeing danger, impulses are sent to the adrenal medulla. It responds by secreting adrenaline into the bloodstream. This results in the following:
- Increased heartbeat
- Diversion of blood from alimentary canal and skin to skeletal muscles.
- Increased breathing rate and depth
- The liver releases more glucose.
These changes increase energy production especially in the skeletal muscles and prepare animal for sudden fight or flight.