Alternate forms of a gene for the same trait are called:

The cytoskeleton is critical to cellular motility, providing structural support and facilitating movement within the cell. It is a dynamic network of protein filaments and tubules that extend throughout the cytoplasm, giving the cell its shape, organizing its internal structure, and enabling various cellular processes. The cytoskeleton is involved in cell motility through the interaction of its components, such as actin filaments, microtubules, and intermediate filaments, with motor proteins that generate force and movement. Cytoskeletal elements are responsible for processes such as cell crawling, cell division, intracellular transport, and the maintenance of cell shape and integrity.

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.

The circulatory system is responsible for transporting oxygen molecules to different locations throughout the body. Oxygen is crucial for cellular respiration, the process by which cells generate ATP (adenosine triphosphate), the energy currency of the cell. In the circulatory system, oxygen is transported by red blood cells, which are specialized cells that contain the protein hemoglobin. Hemoglobin binds to oxygen in the lungs, where oxygen concentration is high due to inhalation, and releases it in tissues where oxygen concentration is low due to cellular respiration. This process ensures that oxygen is efficiently delivered to all cells in the body for their metabolic needs.

In the life cycle of humans, only sperm and eggs, the gametes, have a haploid number of chromosomes. Haploid cells contain half the number of chromosomes found in diploid cells, which have two sets of chromosomes (one from each parent). During sexual reproduction, haploid gametes from each parent fuse to form a diploid zygote, which then develops into a new organism with a complete set of chromosomes. This process ensures genetic diversity and contributes to the variation observed within populations of sexually reproducing organisms.