C. The Bering Land Bridge once connected what would be Russia and North America but the the movement of these continents separated the land bridge
Prokaryotic cells do not have membrane bound organelles. Eukaryotic cells do have membrane bound organelles. The membrane controls movement in and out of the cell. ... The cytoplasm fills the space between the nucleus and the cell membrane.
Suppose that part of an amino acid sequence of a protein changed from tyrosine-proline-glycine-alanine to tyrosine-histidine-glycine-alanine. This change was most likely caused by a point mutation called a <u>substitution</u>.
<u>Explanation:</u>
Any protein is synthesized by joining a number of amino acids together. This amino acid is placed based on the sequences of the DNA , for every 3 sequence there is an amino acid that is synthesized and therefore it is called as a triplet codon, since there may be many sequence for a single amino acid we call it as degenerate codon.
The correct options are as follows:
1. C
Homeostasis is the process by which living organisms maintains constant internal environment. Maintaining homeostasis is very important because the survival of the living organism depend on it. In order to maintain homeostasis, the amount of wastes, nutrients and water that is in an organism must be controlled and maintained at optimum level.
2. A.
An organism that can not maintain an homeostasis will die. This is because, lack of homeostasis will disrupt the biochemical reactions which sustains the life activities of the organism and once the biochemical reactions that produce life energy can no longer take place the organism will die.
3. A.
For both unicellular and multi cellular organisms, when they are exposed to water containing no salt, much of the water will move into their cells. This happened because, the level of salt in the interior of the living cells is higher and so the water will move from the medium which has no salt to the inside to the cell where there is salt. This process is known as osmosis. In osmosis water move through a semi permeable membrane from the region of low salt concentration level to the region of higher salt level concentration.
4. D.
Cells in living organisms are able to maintain homeostasis by specializing in specific functions and by working together in cooperatively. Each cell has its own functions which it performs; in the process of its duty, it communicates with other cells which also help it in order to achieve common goals, which is maintenance of homeostasis within the cell.
Answer:
D. Nucleoid
Explanation:
As prokaryotic cells do not have any organelles, they use a nucleoid to store their prokaryotic DNA.
