Answer:
A) the concentration of calcium ions in the sarcoplasm of a resting muscle
Explanation:
Sarcoplasmic reticulum is a system of the membranous sac that is present around each myofibril and is filled with calcium ions. When muscles are in the resting stage, calcium ions are stored in the sarcoplasmic reticulum.
As the muscle action potential triggers change in voltage-gated calcium ion channels of the sarcoplasmic reticulum, the channels are opened to release the calcium ions in the sarcoplasm. Increased calcium ion levels in sarcoplasm make the muscle fibers to contract.
Removal of acetylcholine from the synaptic cleft ends the production of muscle action potential and calcium ions are moved back from the sarcoplasmic reticulum.
Hence, lower levels of calcium ions are maintained in sarcoplasm when the muscles are in the resting stage.
A is the answer
hope this helps
Answer:
trapping microorganisms
Explanation:
The primary role of the lymphatic system is to transport lymph through the body. Lymph is a fluid that contains white blood cells that fight with infection. Besides this immune function, lymphatic system has a role in fat and vitamin absorption and transportation.
Lymphatic system consists of vessels similar to blood vessels and nodes where the lymph is filtered. Lymph capillaries are closed on one side, so lymph does not circulate, but only drains to reach veins. In lymphatic system there is no such thing as a pump (only lymphatic vessels and lymph nodes).
Roots will always grow down due to geotropism. It is caused by the statocytes in the root cap. They sense the force of gravity and grow down according to it. But if the root does not have a root cap, then the plant will not necesarily grow down. And if the seed is layed on a flat place like a counter, then the roots will grow any which-way
