The correct answer is (B) Photosynthesis and diffusion from the air
Dissolved oxygen enters the water from photosynthesis and through air. The The aeration of water can be caused by wind. From the air oxygen diffuse into the water and gets mixed in the it through circulation. The oxygen is also produced as a waste product of photosynthesis from blue-green algae, phytoplankton, etc which is added in water.
They breathe through their skin. Air dissolves on the mucus of their skin, so they MUST stay moist to breathe.
If worms dry out, they suffocate. As fresh air is taken in through the skin, oxygen is drawn into the worm's circulatory system, and the worm's hearts pump the oxygenated blood to the head area.
Answer:
Alcohol fermentation
Explanation:
When oxygen availability is low, the cell can't perform aerobic respiration to breakdown glucose. Instead, anaerobic respiration must be performed. This occurs in cells which consume large amounts of energy, such as muscle cells. Anaerobic respiration produces much less energy than aerobic respiration
One type of anaerobic respiration formed by yeast is called alcohol fermentation (also called ethanol fermentation). This begins with glycolysis, where one molecule of glucose is broke down into 2 molecules of pyruvate. The energy from this reaction generates 2 molecules of ATP, and converts NAD+ to NADH.
Then, the two molecules of pyruvate are further broke down into 2 acetaldehydes (releasing two molecules of carbon dioxide as a by-product). These two molecules of acetaldehyde are then converted into tw molecules of ethanol, using the H ions from NADH, converting it back to NAD+. See the attached picture
This process is taken advantage of to brew beer and wine.