B) lipids since I saw this answer before
C is your answer :)
And also C and D are true but its C.
This question is on Yahoo Answers
<span>The two different kinds of t-cells are the Helper t-cells and the killer t-cells.
T cells are named T cells after the thymus, an organ situated under the breastbone. They are produced in the bone marrow and later move to the thymus where they mature. Helper T cells have a primary tsak of activating the B cells and killer T cells. The killer T cells are specialized in attacking cells of the body infected by viruses and sometimes also by bacteria. Additionally, they can attack cancer cells.</span>
Answer:
Because of the chemical and structural nature of the phospholipid lipid by layer the lipid soluble molecule can just pass the lipid membrane and some small molecules can also pass freely.
Explanation:
as we know that the homeostasis is an important process for a living cell to maintain it self so for the the exchange of materials between the external and internal environment is must so for that it exchange material with the outside environment of the cell.as the cell membrane is semipermeable(mean allow some molecule to pass(lipid soluble) and not others(lipid non soluble) to pass through the membrane.the cell membrane is selectively permeable due to its nature and chemical composition the chemical composition is lipid and phosphate and glycerol(head) with fatty acid that may b saturated or unsaturated(tail).so finally all those molecule which are polar can not pass through the membrane and non polar can pass the membrane.The size of the molecule is also a factor on which the permeability depends.
Answer:
C. Joining of self-replication molecules into protocells.
Explanation:
For the origin of life, at least three conditions are needed.
- there must have been a supply of replicators, that is, self-replicating molecules.
- copying of these replicators must have been subject to error through mutation.
- the system of replicators must have required a continuous supply of free energy and partial isolation from the general environment.
The radiation received from the sun on the early earth must have fulfilled the requirement of mutation. The mutation is necessary for bringing variation in the genetic material thus driving evolution. To protect the self-replicating molecules from the external environment and to keep them together, the molecules must have been enclosed in a membrane barrier, which should be selectively semipermeable, to facilitate the exchange of molecules.
