Striated muscles contain repeating sarcomeres of overlapping arrays of long, thin actin and thicker myosin filaments. Myosin filaments contains the myosin heads, which are enzymes that can bind to actin, split and make use of the energy from ATP. When muscle contraction starts, myosin heads bind to actin, change their configuration on actin, liberating the products of ATP hydrolysis and causing slide of the actin and myosin filaments. The action of the proteins troponin and tropomyosin on the actin filaments regulates vertebrae striated muscle contraction. The release of calcium ions from the sarcoplasmic reticulum is triggered by the nervous stimulation which causes depolarization of muscle membrane. Calcium ions bind to troponin and thus cause or allow the tropomyosin strands on the actin filament to move so that the part of the actin surface where myosin heads need to bind is uncovered. Contraction then occurs and only stops when the sarcoplasmic reticulum pumps calcium out of the muscle interior.
So basically, what triggers the uncovering of the myosin binding site on actin is the calcium ions binding to troponin and changing configuration.
Answer: A. True.
Explanation: A substance or material is hazardous if can be dangerous to a susceptible agent. This susceptible agent can be a human being, an animal, a plant, a fungi or any other living form, or an environment agents like water, soils, air etc. that can be contaminated with it and later could be dangerous for a living forms.
The best and most correct answer among the choices provided by the question is the second choice. The <span>numbered fossil that has been found in the lowest layer of sediment is 7. </span>I hope my answer has come to your help. God bless and have a nice day ahead!
When water freezes, it becomes less dense.
Answer:
C. birds that use the trout as a source of food
Explanation:
Living organisms feed on one another in their natural environment in order to obtain energy for their various activities. According to this question, overfishing by humans decreases the population of trout living in a particular river.
This means that in that aquatic ecosystem (river), the population of organisms that feed on trout as a source of energy will also decrease. In this case, it is the birds. Hence, birds that use the trout as a source of food.
