Answer:
C)
Explanation:
antigen binding to B cell receptors
Answer:
Active transport often takes place in the internal lining of the small intestine.
Explanation:
Answer:
The correct answer is 3: "<em>High levels of Ca2+ are expected to be found </em><em>within the sarcoplasmic reticulum</em>".
Explanation:
Muscular contraction is a highly regulated process that depends on free calcium concentration in the cytoplasm. Amounts of cytoplasmic calcium are regulated by <u>sarcoplasmic reticulum</u> that functions as a storage of the ion.
When a nerve impulse reaches the membrane of a muscle fiber, through acetylcholine release, the membrane depolarizes producing the entrance of calcium from <u>extracellular space</u>. The impulse is transmitted along the membrane to the sarcoplasmic reticulum, from where calcium is released. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. The calcium channel in the sarcoplasmic reticulum controls the ion release, that activates and regulates muscle contraction, by increasing its cytoplasmic levels. When <em>calcium binds to the troponin C</em>, <em>the troponin T alters the tropomyosin by moving it and then unblocks the binding sites,</em> making possible the formation of <em>cross-bridges between actin and myosin filaments.</em> When myosin binds to the uncovered actin-binding sites, ATP is transformed into ADP and inorganic phosphate.
Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
With respect to the cell wall of fungi and plants, it is correct to state that both cell walls provide structural support but fungi is made of polysaccharides and chitin and plants are made of cellulose.
Explanation:
The cell wall is the most external structure of the cells of fungi and plants, giving them form and protection, at the same time that it allows the growth and the function of relation between cells and of these with respect to its environment.
the main difference between the cell wall of fungi and plants is its composition, being in the first ones chitin and glucosamine. In plants, the main component of the cell wall is cellulose.
Learn more:
Differences between fungi and plants brainly.com/question/12501376
