its nitrogen i took the testttttttttttttttttttttttttttttttttt
Answer: circulatory is when ur blood circulates and respiratory is the system we use to breath if I remember correctly
Explanation:
Answer:
B
Explanation:
Valleys are created by streams of running water
A lot of DNA is structural and doesn't pertain to any genetics while it only takes a small change to change something big. DNA mainly uses 4 different chemicals to change itself, not giving a lot of variety. Most animals share around 98% of the same dna with each other. Humans share 50% of their DNA with a banana. Pretty much everything shares the same double helix design as well. So a lot of genetic code looks similar.
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.
