Valleys are one of the most common landforms on the surface of the planet. They are carved by flowing water or flowing ice through the process of erosion, which is the gradual wearing away of Earth surfaces through the action of wind and water.
The cellular respiration processes of all living cells make use of the coenzyme Nicotinamide adenine dinucleotide (NAD). It plays a key role in energy metabolism by accepting and donating electrons.
The NAD coenzyme acts as a hydrogen acceptor in oxidation-reduction reactions. The electron transport chain in cellular respiration is responsible for energy production and is an excellent illustration of NAD's involvement in redox reactions.he NAD coenzyme acts as a hydrogen acceptor in oxidation-reduction reactions. The electron transport chain in cellular respiration is responsible for energy production and is an excellent illustration of NAD's involvement in redox reactions.