Are there answer's to choose from?
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.
Th correct answer is Phloem.
The conducting tissues in plants is called as the vascular tissues. It is made up of more than one type of cell type, that is found in vascular plants. The important components of vascular tissue are xylem and phloem. The function of these tissues are to transport fluid and nutrients inside the plant. Phloem is responsible for the transportation of sugar, protein and organic substances in plants. The vascular plants grow higher than other plants because of this transportation system.
Answer:
Explanation:
The high clouds are cirrus,
The middle clouds are cumulus,
And the low clouds is stratus.
Hope this helps :)
