Biomes
Explanation:
The most comprehensive ecological unit of the biosphere is the biomes.
Biomes are the largest ecological unit of life.
- They are made up of different population, communities, ecosystems of living organisms and their environment.
- A biome is an ecosystem made up of common characteristics in the environment they are found.
- They have internal regularities in the nature and types of fauna and flora found in such areas.
- Examples of biomes are tundra, rainforest, desert etc
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Answer:
The cells need water to maintain their metabolic functions, the way water enters through cells membranes is by osmosis.
Explanation:
The cell membrane is a lipidic bilayer composed of phospholipids and embedded proteins. Phospholipids have the characteristic of being amphiphilic which means that possess hydrophilic and lipophilic characteristics. The most common way is by osmosis, that is a mechanism that moves water from high concentration to less concentration of water. In the cell membrane, there are is channels of proteins called aquaporins that facilitate the pass of water through the membrane. Also, as water is a very small molecule without charge, this characteristic allows passing a limit amount of water molecules through the hydrophilic characteristic of membranes.
Answer:
peptide antigens by MHC class II molecules
Explanation:
Helper T cells are activated by peptide antigens by MHC class II molecules. These antigens express on the surface of antigen-presenting cells (APCs). After activation, the T helper cells divide and secrete cytokines to assist the immune response.
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Answer:
Integrin molecules serve as stable, permanent anchors that anchor a cell to the extracellular matrix.
Explanation:
Integrins are transmembrane protein receptors that attach the cell cytoskeleton to the extracellular matrix (ECM) in animal cells. These glycoproteins (integrins) are highly dynamic heterodimeric molecules that anchor cells in their position and transduce signals into and out of cells. Integrin-ligand binding activates signaling pathways that are involved in fundamental cellular functions including, among others, organization of the cell cytoskeleton, cell migration, regulation of the cell cycle, etc.