Answer:
D. Producing energy
Explanation:
Mitochondria are power houses of the cell
The movement of water molecules in and out of a cell is called osmosis.
Osmosis, or the diffusion of water molecules, is when water molecules flow in or out of a cell from high to low concentrations (down their concentration gradient). The ultimate goal of osmosis is to establish equilibrium between the cell and its outer environment.
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Answer:
The cilia in the upper respiratory tract move mucus down toward the pharynx whereas the cilia in the lower respiratory tract move them up toward the pharynx.
Explanation:
Through the internal nares, the air enters nasopharynx from the nasal cavity. This air has dust-laden mucus. The nasopharynx is lined with ciliated pseudostratified columnar epithelium. These cilia move the mucus down toward the most inferior part of the pharynx. The lining of the larynx inferior to the vocal folds is made up of ciliated pseudostratified columnar epithelium and have ciliated columnar cells, goblet cells, and basal cells.
The goblet cells serve to produce and secrete mucus. The mucus from goblet cells helps trap dust that was not removed in the upper passages. Therefore, the cilia in the upper respiratory tract move mucus and trapped particles down toward the pharynx whereas the cilia in the lower respiratory tract move them up toward the pharynx.
The antigen-binding sites of an antibody molecule are formed from the molecule's variable regions which are described as so because their amino acid sequences can be different on different antibodies.
The specificity of antibodies is determined by the variable regions found at their endpoints. Antibodies are specialized proteins secreted by B-cells of the immune system. They are also called immunoglobulins. They contain four polypeptide chains that comprise two heavy chains and two light chains to form a Y-shaped molecule.
The variable regions, more specifically the hypervariable regions of an antibody, have a high ratio of different amino acids with the most common amino acids provided in one place. The variable region serves as the antigen-binding site while the constant region found below the variable region is determined to invade the antigen.
Antibodies are preserved in our body to identify the antigen the next time it encounters. They send the signals to the other body parts to reject the antigen and invade it.
To know more about variable regions of antibodies, refer to the following link:
brainly.com/question/17439586
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