Evolution would be my guess.
Natrual variations i think
A streamlined body is a body that is shaped to specifically reduce friction drag when moving.
Flippers and flattened tails are used to propel an animal through the water.
A smooth, almost gutless body is light, which is important when animals have to go through water quickly.
A thick layer of blubber is only used for insulation, and would hamper an animal's progress through water due to its weight.
The answer is B. thick layer of blubber.
Answer:
___ 1. Organisms that make their own food
H. Autotrophs
___ 2. Site of photosynthesis
A. Chloroplasts
___ 3. Organism that must consume other organisms to obtain energy.
L. Heterotroph
___ 4. C6H12O6
C. Glucose
___ 5. Process requires oxygen
B. Aerobic
___ 6. Adenosine diphosphate
G. ADP
___ 7. During aerobic respiration, the most ATP is produced during this process.
K. Electron Transport Chain
___ 8. The anaerobic process of splitting glucose and forming two molecules of pyruvic acid
E. Glycolysis
___ 9. Place where glycolysis occurs
F. Cytoplasm
___10. Place where the Krebs cycle occurs
D. Mitochondria
___11. Process does not require oxygen
J. Anaerobic
___12. Energy storing molecule
I. ATP
