Answer:
"As a molecule moves through the plasma membrane it passes through <em>a hydrophilic layer of phospholipid heads then a hydrophobic layer of phospholipid tails and then another hydrophilic layer of phospholipid heads".</em>
Explanation:
Biological membranes are formed by two lipidic layers, proteins, and glucans.
Lipids characterize for being amphipathic molecules, which means that they have both a hydrophilic portion and a hydrophobic portion at the same time. These molecules have a lipidic head that corresponds to a negatively charged phosphate group, which is the polar and hydrophilic portion. They also have two lipidic tails that correspond to the hydrocarbon chains -the apolar and hydrophobic portion- of the fatty acids that esterify glycerol.
Membrane lipids are arranged with their hydrophilic polar heads facing the exterior and the interior of the cells, while their hydrophobic tails are against each other, constituting the internal part of the membrane.
Through this lipidic bilayer, some molecules can move from one side of the cell to the other, which happens because of concentration differences. When this occurs, molecules must pass through the hydrophilic layer of phospholipid heads then through the hydrophobic layer of phospholipid tails and then again through another hydrophilic layer of phospholipid heads.
Substance abuse can spread STIs because when a user shares needles with an infected person, it can spread through the blood. Any high-risk behavior like this spreads STIs.
Answer:
The given blanks can be filled with white pulp and red pulp.
Explanation:
In the lymphatic system, the spleen is considered as the largest organ. It is situated in the upper left part of the abdominal cavity, the main function of the spleen is to filter blood containing the destructed cells, pathogens like viruses and bacteria, and cellular debris.
The spleen generates and develops the mature immune cells, which possess the tendency of finding and eliminating the pathogens. The white pulp of the spleen comprises the immune cells, that is, the B and T lymphocytes, which help in fighting against the pathogens.
On the other hand, the red pulp of the spleen comprises connective tissue called the cords of Billroth, and various splenic sinusoids, which are filled with blood, providing it a red appearance. Its main function is to filter the blood containing microbes, pathogens, and worn-out or the defective RBCs.
Answer: The answer is B
Explanation:
A is not practically possible as mars is such a great distance away
C water of course wasnt around in earth at the time but other planets did have water so this isnt an accurate answer
D cracks me up, Hydrogen was the first element in space after the Big Bang this is also an in accurate answer
A virus is not a living thing. It is made of genetic material inside a protein coat. A virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. It is an infective agent that typically consists of a nucleic acid molecule in a protein coat, is too small to be seen by light microscopy, and is able to multiply only within the living cells of a host.
