Answer:
SI system consist of standard units of measurement that are defined by International System Of Units.
Explanation:
SI stands for Standard International. It consist of total 7 units that are accepted internationally,
Two advantages of SI units are:
- SI unit is rational system of units, that means one unit denotes one physical quantity.
- SI units are internationally accepted which makes researchers and scientist calculations
The longest day of the year isn't the hottest day of the year because the phenomenon of the hottest weather following the summer solstice by a month or two is called the lag of seasons.
Answer: increased
Explanation: the more you have the better you can tell where something is acting on you, ie touch
Answer:
When a muscle cell contracts, the myosin heads each produce a single power stroke.
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, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. 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 liberated. Myofilaments slide impulsed by chemical energy collected in myosin heads, <u>producing a power stroke</u>. 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.
Correct answer: B). The phagocytotic barrier, which is a part of innate immunity
The scenario represents the phagocytosis, which is a type of endocytosis by which the cell engulfs microbial pathogens. The main cells of the immune system that are involved in phagocytosis include macrophages, neutrophils, and dendric cells.
It is a mechanism which is used by the immune system to kill and processing of antigen that play an important role in innate immune response.
Hence, the correct answer would be option B.
