Answer:
Explanation:
Helium is the second most abundant element in the universe, but here on earth, it's rather rare. Most people guess that we extract helium from the air, but actually we dig it out of the ground. Helium can be found in certain parts of the world, notably in Texas, as a minor component in some sources of natural gas.
Helium is generated underground by the radioactive decay of heavy elements such as uranium and thorium. Part of the radiation from these elements consists of alpha particles, which form the nuclei of helium atoms. ... Helium can also be produced by liquefying air and separating the component gases
When the gas contains more than about 0.4% helium by volume, a cryogenic distillation method is often used in order to recover the helium content. Once the helium has been separated from the natural gas, it undergoes further refining to bring it to 99.99+% purity for commercial use.
Active transport moves molecules across the plasma membrane of a cell with the help of transport proteins and energy (ATP).
Active transport is the means of transport of molecules across the plasma membrane with the help of energy. This method is usually used for the transport of molecule against their concentration gradient, i.e., from lower concentration to higher concentration.
Plasma membrane is the outer layer surrounding the cell. It is made up of lipid bilayer, proteins, carbohydrates and cholesterol. The lipid bilayer is amphipathic since the lipid head is hydrophilic and its tail is hydrophobic. The plasma membrane is semi-permeable in nature.
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Answer:
A and B
Explanation:
That's about 3L because at any given time the viens hold about 70% of blood because they have thinner and less rigid walls so 0.7*5 is about 3L
The correct order of the following events on the mass flow of materials in the phloem is:
- Leaf cells produce sugar by photosynthesis.
- Solutes are actively transported into sieve tubes.
- Water diffuses into the sieve tubes.
- Sugar moves down the stem.
Correct answer: letter C.
This is because the mass flow of materials in the phloem must pass through all these processes in a consecutive and orderly manner, from the cell to the stem, in order to allow nutrients and other vital materials to reach from the plant roots to the leaves and fruits.
<h3>How is this transport of nutrients and other vital materials achieved?</h3>
This is accomplished by the transport of solutes through the phloem's network of channels, which contain fluids, mineral salts, vitamins and other nutrients essential to plant health. Mass flow also helps distribute oxygen and carbon dioxide to all parts of the plant. These materials are necessary for plant respiration and growth.
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