What molecules make up the cellular membrane?

The zygomatic arch, also known as the cheekbone or zygoma, is a prominent facial bone that forms part of the structure of the face. A fracture of the zygomatic arch would be located in the facial region. The zygomatic arch extends horizontally from the area near the ear to the region of the cheekbone, contributing to the overall shape and support of the face. Fractures of the zygomatic arch can result from trauma to the face, such as blunt force impact, and may cause pain, swelling, deformity, and difficulty with chewing or facial movement.

The aerodynamic nature of a bird's wing is an example of the central theme in biology known as "Structure and function." This theme emphasizes the relationship between the form and function of biological structures. In the case of a bird's wing, its structure, including its shape, size, and arrangement of feathers, is intricately related to its function, which is to provide lift and thrust for flight. The specific structure of the wing, such as the curvature of the airfoil shape, enables it to generate lift by creating a pressure differential between the upper and lower surfaces of the wing when air flows over it. Thus, the structure of the wing is adapted to its function of facilitating flight in birds.

Contractile vacuoles are organelles found in some protists and single-celled organisms, primarily freshwater unicellular organisms. These vacuoles are responsible for regulating the water content of the cell by actively pumping excess water out of the cell. Contractile vacuoles collect excess water from the cytoplasm through a process of osmosis, where water diffuses into the cell due to differences in solute concentration between the cell and its environment. Once filled, contractile vacuoles contract rhythmically, expelling the excess water from the cell to maintain osmotic balance and prevent cell swelling or bursting. This process is particularly important for organisms living in hypotonic environments where water uptake is significant.

The process described, where many solute particles must use a channel protein to move from a high concentration inside the cell to a lower concentration outside the cell, is called "Facilitated diffusion." This process involves the passive movement of molecules across a biological membrane with the assistance of transport proteins. Channel proteins are one type of transport protein that facilitates the diffusion of specific molecules, such as ions or polar molecules, across the membrane by providing a channel through which these molecules can pass. Facilitated diffusion does not require energy input from the cell and occurs down the concentration gradient, from areas of higher concentration to areas of lower concentration.