Answer:
defines the problem to be explored
Answer:
c is just wrong because that is not how evolution works evolution is a small change in the DNA that takes a long time through many many generations not just as you or an organism get older and smarter you are not evolving
Can you provide more details ?
Answer:
The correct answer is c) are plant cells.
Explanation:
The cells cannot be animal cells, because they have not wall (this kind of cells has only plasma membrane). In addition, eukaryotic cells have membrane-bound organelles (which are surrounded by a phospholipids membrane, such as endoplasmatic reticulum, Golgi apparatus, lysosomes, etc.), whereas prokaryotic cells lack them. Since plant cells are eukaryotic and bacterial cells are prokaryotic, the cells you are looking are plant cells.
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.
