The reason why nost scientists thought that the first true cells formed on Earth were anaerobic is being shown in the second option :B. because there was no oxygen on early Earth. Paying attention to this fact scientists discovered that first cells were prokaryotes and greatest part of them created oxygen as a toxic by-product of their own metabolism which make them understand how the planet was provided with oxygen and made a conclusion that first cells were anaerobic.
Answer:
Hey there the answer would be D. Keratin is the pigment responsable for skin color.
Explanation:
A. The top layer of the epidermus is made of dead skin cells. The inner player has to be constatnly making more cells
B.The body procudes more melanin with stronger sunlight exposure. This results because the UV of the sun causes T-T dimers which is a type of DNA damage.
C. UV causes genetic mutation which can result in cancer if not fixed by the cell
D.Keratin is found in the epidermis and with thick layer of skin found in the hands and feet. Melainin is responsible for skin color.
The answer is mitochondria because mitochondria is involved in cellular respiration.
The size of food web is limited by the number of animals included in the area.
-Pepetreefrogthe2nd
