Answer:
There are seven main taxonomic ranks: kingdom, phylum or division, class, order, family, genus, species.
Explanation:
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Answer:
Water, carbon dioxide, and oxygen are among the few simple molecules that can cross the cell membrane by diffusion
Explanation:
Transport proteins generally perform two types of transport: “facilitated diffusion,” where a transport protein simply creates an opening for a substance to diffuse down its concentration gradient; and “active transport,” where the cell expends energy in order to move a substance against its concentration gradient
Though the skeletal muscle cells are of different sizes and shapes, the main components of a skeletal muscle cell remain the same. The skeletal muscle is enveloped by a layer of connective tissue called epimysium, it protects the muscles from friction against the bones and other muscles.
The skeletal muscles are also covered by a fibrous connective tissue called endomysium that insulates each muscle fiber. Underneath the endomysium is the sarcolemma that is the cell membrane of the fibers and underneath that is the sarcoplasm that is the cytoplasm of the cell.
Each muscle fiber also comprises cylindrical organelles called myofibrils. Each muscle fiber comprises hundreds to thousands of myofibrils. The myofibrils are the bundles of myosin and actin proteins that go through the length of the muscle fiber and plays an essential role in the contraction of muscles.
The myofibrils are surrounded by a network of tubules and channels known as the sarcoplasmic reticulum, which is stored with calcium and is essential for the contraction of muscles. Each myofibril can be further dissociated into functional repeating segments known as sarcomeres.
