Answer:
Humoral immunity involves <u>B cells</u> and<u> recognize antigens or pathogens in the lymph or blood.</u>
Explanation:
Humoral immunity is defined as the immunity which is mediated by several macromolecules presnet in the extracellular fluids such as antibodies, certain antimicrobial peptides, and complement proteins.
Humoral immunity allows to distinguishes two groups of foreign substances. it involves <u>B cells</u> and<u> recognize antigens or pathogens in the lymph or blood. </u>
Humoral immunity begins when an antigens bind to B cells. Interleukins or helper T cells provides a secondary signal to the B cells that activates a B cell and allows B cell proliferation. which roduces produce plasma cells. The plasma cell then produces antibodies which are identical to the specific antigen. The antibodies are the released and circulate through the body, binding to antigens. B cells the further produces memory cellss for future immunity.
So, Humoral immunity involves <u>B cells</u> and<u> recognize antigens or pathogens in the lymph or blood.</u>
Answer:
chitin
Explanation:
chitin is a complex carbohydrates, similar to cellulose, that makes up organic structure, such as the cell walls of fungi and exoskeletons of insects and other arthropods.
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.
According to science, D would be the correct answer. Hope this helps!
6. is Saprophytic
7. Parasitic
8. Either mimetic or mutualistic i think mutualistic
