B. Embryos are being collected by the student on the field trip.
Antibiotics are drugs that are able to fight diseases caused by bacteria. Besides, it is a "golden solution" that can kill harmful bacteria (pathogenic bacteria such as fungi, actinomycetes, ...), has the effect of inhibiting the growth and spread of of these bacteria.
Answer and Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is released. Myofilaments slide impulsed by chemical energy collected in myosin heads, producing a power stroke. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
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Explanation:
The hydrogen ion concentration of a solution is indicated by its <u>pH </u>value.
Explanation:
- A measure of acidity or alkalinity of water soluble substances (pH stands for 'potential of Hydrogen'). A pH value is a number from 1 to 14, with 7 as the middle point.
- Under normal circumstances this means that the concentration of hydrogen ions in acidic solution can be taken to be equal to the concentration of the acid.
- The pH is then equal to minus the logarithm of the concentration value.
- Values below 7 indicate acidity which increases as the number decreases, 1 being the most acidic.
- The pH of a solution is a measure of hydrogen ion concentration, which in turn is a measure of its acidity.
- Pure water dissociates slightly into equal concentrations of hydrogen and hydroxyl (OH−) ions. For a neutral solution, [H+] is 10−7, or pH = 7.