"The common ancestor of protists gave rise to many other types of eukaryotes" statement about protists explains its revised classification.
<u>Option: B</u>
<u>Explanation:</u>
All protists have the principal characteristic that they are eukaryotic organisms. This implies they consist a nucleus that is contained to the membrane. Many researchers believe that, when these three kingdoms deviated from general protist-like ancestor, billions of years ago, protists created a connection among plants, animals and fungi.
While this protist-like ancestor is a hypothetical creature, these ancient species can be traced to other genes present in modern animals and plants. Hence, historically, these species are deemed the first eukaryotic types of life and a precursor to fungi, plants and animals.
A model is a representation of something in the natural world
Answer:
1.An action potential is conducted deep into the muscle fiber by the T tubule.
3.The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
4.Calcium ions diffuse into the sarcoplasm around the myofibril.
2.Calcium ions bind to troponin.
5.The troponin-tropomyosin complex moves exposing active sites.
Explanation:
The arrival of a nerve impulse at synaptic end bulbs stimulates the release of acetylcholine into the synaptic cleft. The acetylcholine binds to its receptors located on the motor end-plate followed by the opening of ion channels to allow the small cations such as Na+ to enter the muscle fiber and make it positive.
The change in the membrane potential triggers the action potential that propagates along the sarcolemma into the T tubules. The action potential stimulates the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm.
The released calcium ions combine with troponin. Binding of calcium ions to troponin stimulates conformational change in troponin that makes the tropomyosin to shift away from the myosin-binding sites of actin.
The myosin heads join the free binding sites to form cross-bridges leading to contraction of muscle fiber.
The bone cell responsible for breaking down bone tissue is the osteoclast, whereas the bone cell that produces new bone tissue is the osteoblast.
<h3>
What is osteoclast and osteoblast?</h3>
- In those processes, osteoblast and osteoclast are the two major cells involved.
- Aged bone resorption is caused by osteoclasts, whereas new bone creation is caused by osteoblasts.
- Under healthy settings, the processes of resorption and creation are steady.
- The cells known as osteoclasts mediate bone loss in pathologic situations by increasing their resorptive activity and degrading bone to start normal bone rebuilding.
- They originate from myeloid/monocyte lineage progenitors that circulate in the circulation after developing in the bone marrow.
- On the surface of bones, there are osteoblasts, bone lining cells, and osteoclasts, which develop from progenitor cells, which are regional mesenchymal cells.
- Osteocytes are created by the fusing of mononuclear blood-borne progenitor cells, and they penetrate the interior of the bone.
Learn more about osteoclast and osteoblast here:
brainly.com/question/8057275
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<span>Cells that have differentiated still have most of their genes and they </span><span>can still express those genes.
Hope this helps (:
-Payshence xoxo
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