oxygen

The human brain needs to be without oxygen for only four minutes before permanent damage occurs.

The more you exert yourself, the faster you consume oxygen.

And there they stimulate the explosive growth of algae and that uses up much of the oxygen in the water, oxygen that fish and other aquatic organisms need to stay alive.

When the water warms up, the concentration of dissolved oxygen in the water decreases.

Because liquid water was present, self-replicating molecules of carbon, hydrogen, and oxygen developed life early in Earth's history and have radically modified its surface, blanketing huge parts of the continents with greenery.

I thought the Permian Extinction was caused by a decline in sea water oxygen levels.

Some tropical termites are more ingenious engineers, constructing huge above-ground nests with built-in “air conditioning” that keeps the nest moist, at a constant temperature, and well supplied with oxygen.

Its many occupants require over 250 quarts of oxygen (more than 1,200 quarts of air) per day.

How can so much oxygen diffuse through the thick walls of the mound?

Gases, mainly oxygen coming in and carbon dioxide going out, easily diffuse into or out of the ridges, since their walls are thin and their surface area is large because they protrude far out from the wall of the mound.

Thus air that flows down into the cellar through the ridges is relatively rich in oxygen, and has lost much of its carbon dioxide.

It supplies the nest’s inhabitants with fresh oxygen as it rises through the fungus-growing area back up to the attic.

Gills were undoubtedly the main source of oxygen for these fish, but the lungs served as an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought.

So, these fish had already evolved one of the prime requisites for living on land: the ability to use air as a source of oxygen.

They could have been used as feeble locomotor devices on land, perhaps good enough to allow a fish to flop its way from one pool of water that was almost dry to an adjacent pond that had enough water and oxygen for survival.

This accumulation, in turn, reduces the water movement and the oxygen supply.

The high rate of metabolism (the processing of energy for survival) of the microorganisms in the sediments causes sediments to be anaerobic (without oxygen) below the first few millimeters.

Over time, the rising temperatures would have leveled off, solar ultraviolet radiation having broken down atmospheric water vapor molecules into hydrogen and oxygen.

Oxygen gets chemically combined with sugars in our cells and the energy produced from that reaction is then used to power the cells.

APS digestion uses anaerobic bacteria, ones that thrive in the absence of oxygen, to consume, to break down organic material.

Uh, like you might get just a little bit tired out after the first few thousand kilometers or so, uh, especially with all the oxygen tanks you’ll have to be hauling up with you.

However, we now know that since oxygen levels were much lower in the Mesozoic than we assumed, there was much less plant life for sauropods to eat than we thought.

So they can store more oxygen because they have more blood?

They also have a greater capacity than land animals to store oxygen in their blood.

Whales carefully conserve their oxygen when underwater in a couple of ways.

A whale's muscles and non-vital organs are able to function without oxygen for an extended period of time.

It subconsciously adjusts breathing rate and depth in order to regulate the levels of carbon dioxide (CO and oxygen (O, and the acid-base ratio in the blood.

This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less oxygen and produces less carbon dioxide.