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e. Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment.
Osmosis is the movement of a solvent across a semipermeable membrane toward a higher concentration of solute. In biological systems, the solvent is typically water, but osmosis can occur in other liquids, supercritical liquids, and even gases. [11][12] When a cell is submerged in water, the water molecules pass through the cell membrane from an ...
GCSE Bitesize was launched in January 1998, covering seven subjects. For each subject, a one- or two-hour long TV programme would be broadcast overnight in the BBC Learning Zone block, and supporting material was available in books and on the BBC website. At the time, only around 9% of UK households had access to the internet at home.
Bicarbonate indicator. A hydrogencarbonate indicator (hydrogencarbonate indicator) is a type of pH indicator that is sensitive enough to show a color change as the concentration of carbon dioxide gas in an aqueous solution increases. The indicator is used in photosynthesis and respiration experiments to find out whether carbon dioxide is being ...
Evaporation. Aerosol of microscopic water droplets suspended in the air above a cup of hot tea after the water vapor has sufficiently cooled and condensed. Water vapor is an invisible gas, but the clouds of condensed droplets refract and scatter the sunlight and are thus visible. Droplets of water vapor in a pan.
Breathing. Real-time magnetic resonance imaging of the human thorax during breathing. X-ray video of a female American alligator while breathing. Breathing (spiration[1] or ventilation) is the rhythmical process of moving air into (inhalation) and out of (exhalation) the lungs to facilitate gas exchange with the internal environment, mostly to ...
Cellular respiration is the process by which biological fuels are oxidised in the presence of an inorganic electron acceptor, such as oxygen, to produce large amounts of energy and drive the bulk production of ATP. Anaerobic respiration is used by microorganisms, either bacteria or archaea, in which neither oxygen (aerobic respiration) nor ...
Hydrocarbon. Ball-and-stick model of the methane molecule, CH 4. Methane is part of a homologous series known as the alkanes, which contain single bonds only. In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. [1]: 620 Hydrocarbons are examples of group 14 hydrides.