those are nucleotides 
since all three of them contain deoxyribose (because there's only one hydroxil group) they are DNA nucleotides
the first nucleotide has cytosine as it's nitrogenous base 
the second nucleotide has adenine as it's nitrogenous base 
the third nucleotide has thymine as it's nitrogenous base
 
        
             
        
        
        
<span>Not every member of a particular species (one kind of organism) must be able to reproduce in order for the species to survive. If you take homo sapiens for example (Humans) there are many males and females around the world who are sterile and unable to reproduce, yet you still see the human species flourishing. </span>
        
             
        
        
        
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:
Roughage
Explanation:
Hope this helps :)-Mark Brainiest Please! Thanks!!
 
        
             
        
        
        
Answer:
Disruptions to any physical or biological component of an ecosystem can lead to shifts in all its populations. Biodiversity describes the variety of species found in Earth`s terrestrial and oceanic ecosystems. The completeness or integrity of an ecosystem`s biodiversity is often used as a measure of its health.
Explanation: Disruptions can really mess with any physical or biological component of a ecosystem then that ecosystem leads to shifts in all populations. I hope this answer helps you!