Without efficient nutrient absorption, our body won’t function properly leaving us susceptible to deficiencies and disease.
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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.
 
        
             
        
        
        
The conversion of one form of energy into another, or the movement of energy from one place to another. Solar panels allow for energy transfer from light energy to heat and electrical energy.
        
             
        
        
        
Answer:
Our immune system produces antibodies against that antigen of pathogen.
Explanation:
Injecting an antigen from a pathogen would help our immune system memorize the infection and protect our body from causing of the disease because our immune system produces antibodies against that antigen so when the pathogen enters our body these antibodies attack on that and prevent them of causing infection in the body so that's why injecting an  antigen has to be done from the childhood to prevent diseases.