Depending on the structure of cells (shapes and organelles) we can differentiate cells and therefore create different groups and classifications based on their differences and functions.
The eukaryote-prokaryote division bases itself on the possesion of a nucleus that creates a boundary for the genetic materifal. In this case, eukaryotes have it while prokaryotes don't.
Hope it helped,
BiologiaMagister
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 answer should be the refractory period
<span>There is no set number of genes that produces a new species. </span>
Answer:
With decrease in pH of ocean water, the survival rate of corals, algae, and fish in coral reef reduces.
Explanation:
Coral reefs find difficulty in living in acidic ocean water. It is so because the coral’s shell that is made up of calcium carbonate is unable to sustain in acidic environment.
Not only this the skeleton of snails, clams, algae , fish etc is also made up of calcium carbonate. Increased acidity leads to death of these species.
Thus, the lower is the pH of ocean water, the higher is its acidity and hence the lower is the probability of survival of corals, algae, and fish in the coral reef
