Answer:
oxygenation of the atmosphere
Explanation:
The "Great Oxidation Event" was one of the most important things happening on this planet. Without it, there could never be animals breathing oxygen, like insects, fish, and certainly humans. Moreover, this moment of our planet was one of the main responsible for the evolution of eukaryotes.
For decades, scientists have worked to understand how and why oxygen emerged. And they suspect that life itself was responsible for creating the air we breathe.
The latest findings suggest that life was undergoing a tremendous transformation before the "Great Oxidation." An evolutionary leap that helps explain what we know today.
Formed 4.5 billion years ago, the Earth, at the time of the Great Oxidation, was already inhabited. But only by unicellular organisms. It is not exactly clear when life began on the planet, but the oldest fossils of these microorganisms date back at least 3.5 billion years ago. This suggests that life had existed on earth almost 1 billion years before the "Great Oxidation." From the moment oxygen spread through the atmosphere, it was possible for these organisms to evolve into more complex life forms.
Considering the answers
A. GTT
B. TCT
C. TCC
D. GCA
The answer would be A. GTT
A sequence of amino acids in a protein determines its functions. The DNA sequence of a gene determines the amino acid sequence of the resulting protein, therefore, any changes in DNA sequences can result in changes in protein function.
Hibernation helps animals survive the changing seasons. Foods that bears eat, such as berries and flowers, are much less available during cold winter months. When they hibernate, bears enter a deep sleep. ... While they sleep, the bears can survive because their bodies live off of their stored fat or food.
During hibernation, the animal’s body temperature, heart rate and breathing rate all drop to significantly lower levels. Animals do this to survive the winter because the weather is cold and food is scarce. It is advantageous because these animals can quite literally shut themselves off for weeks at a time rather than try and survive through harsh weather conditions.
While many people think bears are hibernators, they actually participate in a similar, though not exact, practice. Instead of hibernating, bears fall into a deep sleep called torpor. During torpor, heart rate and breathing rate decreases, body temperature reduces slightly and bears do not eat or release bodily waste. Bears can sleep more than 100 days without eating, drinking, or passing waste!
Bears sleep in dens that they make themselves, as well as in hollow trees, caves and dens built by other bears. A den can be built in 3–7 days, however, the timing of den building varies from bear to bear. While some bears build their dens months before hibernation season, others choose to excavate their dens.
These animals can dramatically drop their body temperature to below freezing—salty body fluids work to prevent tissue crystallization in particularly cold temperatures.
So really, animals that are true hibernators don’t actually sleep through the entire winter.
The urea produced by their fat metabolism is broken down and the nitrogen is re-used by the bear to rebuild protein.