Answer:
Evolution.
Explanation:
It might have acquired the ability to cause disease due to evolution. Due to evolution, the harmless bacteria can turn into infectious pathogens that cause diseases. Evolution is the change in the characteristics of a species over several generations due to the process of natural selection. This evolution in the bacteria occurs due to changing of environmental conditions which changes the genetic makeup of that harmless bacteria and turn into infectious pathogen.
Because if a cactus didn't have needles a lot of animals wouldn't get poked and they'd eat it
Answer:
The 6 Main Elements are Hydrogen, oxygen, carbon, Nitrogen, calcium & phosphorus
Explanation:
99% of the atoms in the human body come from 6 elements: Hydrogen at about 63%, oxygen (around 25%), carbon (nearly 11%), nitrogen (nearly 0.7%), calcium (0.25%), phosphorus (0.15%) and Calcium which is essential for our bones, & contains 99% of the calcium in the human body
Answer:
D. Calcium ions.
Explanation:
Here we are talking about the mechanism of muscle contraction. The most accepted theory of muscle contraction is sliding filament theory. It was given by Huxley and Huxley. During the process actin filaments slides over myosin filament by forming cross bridges. The sequence of events are as follows:
a. An action potential propagates through the motor nerve and reach the nerve endings on the muscle fiber at neuro-muscular junction.
b. Neurotransmitter called acetylcholine is released by the nerve endings.
c. Acetylcholine binds to the receptors on muscle fiber and opens the gated channels which causes flow of Na+ ions into the muscle fiber.
d. This influx of sodium ions initiates an action potential in the muscle fiber which reaches the T- tubules or transverse tubules. Here it causes the sarcoplasmic reticulum to release large amounts of calcium ion.
e. Calcium ions are responsible for initiating the attractive forces between actin and myosin filaments. Cross bridges are formed, actin slides over myosin causing the contraction of muscle.
