Answer:
it's called the threshold potential.
Explanation:
it triggers the nerve impulse, or action potential
Natural barriers include the skin, mucous membranes, tears, earwax, mucus, and stomach acid. Also, the normal flow of urine washes out microorganisms that enter the urinary tract. The immune system uses white blood cells and antibodies to identify and eliminate organisms that get through the body's natural barriers.
Answer:
C) The continents were once connected.
Explanation:
All the continents were once part of the super-continent called Pangaea. Continental drift split it into fragments and led to the formation of the present-day continents. Since all the continents were connected, some of the cacti native to tropical western Africa must have been carried to present-day America.
The cacti populations present in America and tropical western Africa accumulated genetic variations to get adapted to the prevailing environmental conditions. Separation of continents by continental drift led to their geographical isolation and prevented any interbreeding between the populations. Over generations, the cacti present in two continents evolved into separate species.
Answer:
they are relitivly the same shape and one has hair and one dosn`t. aisan elaphants were hunted to extinxtion
Explanation:
