Explanation:
To swim, they move their tails up and down, rather than back and forth as fishes do. This is because whales evolved from walking land mammals whose backbones did not naturally bend side to side, but up and down. ... Whales do the same thing as they swim, showing their ancient terrestrial heritage.
Cetaceans are fully aquatic marine mammals belonging to the order Artiodactyla, and branched off from other artiodactyls around 50 mya (million years ago). Cetaceans are thought to have evolved during the Eocene or earlier, sharing a closest common ancestor with hippopotamuses.
Answer:
Parasitism describes a relationship between two organisms where one gets benefit and other get harm.
Explanation:
Parasitism is a type of symbiotic association that is present between two different organisms. In association, one organism gets benefit from the other and the other is damaged. For example, association between mosquitoes and human is parasitism because mosquitoes get benefit in the form of food while human is damaged due to disease cause by mosquito biting.
Answer:
This nucleus then acquires <u><em>one </em></u>electron to become electrically neutral.
Explanation:
Fusion :It is nuclear reaction which two or more than smaller nuclei combines together to form heavy nuclear.
A neutron combines with proton in order to make heavy electron that is fusion reaction is taking place.

The overall charge in the nucleus will be +1.And in order to neutralize this positive charge the nucleus will acquire single electron to become electrically neutral.
Proteins is used to build and repair cells.
Protein can be found in every living cell and it is very
important building block in the body. Protein supply amino acids which were
being used to create and repair cells, enzymes, red blood cells, antibodies and
tissues. In the body, protein functions by maintaining fluid balance and
transportation substances. Protein can be gotten from meat, dairy products, soyabeans,
nuts, beans and certain grains. However,
protein from meat and other animal products are known as complete protein.
Hi , the answer is December 31st around 10;30pm.