Answer: Scientists think that early amphibians had lungs becuase they needed efficient oxygen uptake to support their metabolism. Higher rates of metabolism are needed on land, becuase of this scientist think that early amphibians breathed air with lungs.
Explanation:
I'm not sure.... but Manuel scalpels?
Answer:
B. 20%
Explanation:
The complementary base-pairing rule states that Adenine always pairs with Thymine (A with T), and Cytosine with Guanine (C with G).
Because of this, the amount of Adenine present must be the same as the amount of Thymine present, and the same for Cytosine and Guanine.
This means that if there is 30% Adenine, there is also 30% Thymine as each A base is paired to a T base. This adds to 60%, so Cytosine amounts and Guanine amounts must add to 40% to make 100%.
Since they are equal in amount, there must be 20% of each.
Therefore the answer is B. 20%
There is 30% Adenine, 30% Thymine, 20% Guanine and 20% Cytosine.
Hope this helped!
The correct answer is option d, that is, glaciers and icecaps.
Though the amount of water present in the glaciers and the ice caps is a small ratio in comparison to the total water found in and on the Earth, it demonstrates a huge ratio of the world's entire freshwater.
On the basis of the data, about 1.7 percent of all the water found on Earth is locked up in snow and ice, however, the majority of the entire freshwater on the planet, that is, about 68 percent is captivated in glaciers and ice caps.
Answer: Oxygen has a negative ion.
Explanation: In a water molecule, the oxygen atom and hydrogen atoms share electrons in covalent bonds, but the sharing is not equal. The unequal sharing of electrons gives the water molecule a slight negative charge near its oxygen atom and a slight positive charge near its hydrogen atoms.
