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.
Answer:
the food that they ate
Explanation:
The beaks of finches found on various Galápagos Islands differed based on the food that they ate. The finches that survived on eating different larger nuts had strong beaks for breaking the nuts open. While the Finches that ate smaller type nuts and seeds had beaks for cracking nuts and seeds. This also applied to other types of animals as well, each adapting to its own necessities.
Answer:
The elecron cloud is located around the nucleus.
The electron cloud contains negitivley-charged electrons.
A higher effectivly nuclear charge causes greater attractions to the electrons causing them to come closer.
The faster a electron goes the farther away it will go.
Answer:
solar radiation is the heat energy received from the sun into the solar system that also reaches the earth.
Polar regions receive the least amount of solar radiation, therefore, they have colder climates.
The equator receives the most amount of solar radiation, therefore, they have warmer to hot climates.
Explanation:
