They are known as Gametes
Answer:
Pigmentation, (skin color), in humans has evolved under selection pressure from the duration and intensity of sunlight. Ancestral populations near the equator were selected for dark skin, while those living in higher northern latitudes were selected for lighter skin.
Answer:
If I add sugar or salt, the water's density will increase.
Explanation:
Density is the relation between mass and volume. We can represent it with the formula δ= m/v. Where δ stans for density, m for mass, v for volume.
If we add salt or sugar, we increase the mass, but the volume is the same. As a result, the density will increase.
We can use numbers to understand it better.
Suppose that before adding salt or sugar, the mass is 1 g and the volume is 1 l
δ= 1g/l1t
δ= 1 g/lt
Now, if we add sugar or salt, the mass increases. Suppose that we have 2g of mass and the volume is the same, 1l.
δ= 2g/1lt
δ= 2g/lt
We can see that the density increased when the mass increased.
Answer:
Mannitol is a drug that temporarily disrupts tight junctions. This drug is often added to medications that need to get into the extra-cellular fluid of the brain because it will make the capillaries of the <u>blood-brain barrier </u>more permeable to larger molecules.
Explanation:
The blood-brain barrier's components are endothelial cells, basement membrane, pericytes, and astrocyte endfeet. The gaps between endothelial cells are small. As a consequence, they form tight junctions that allow the passage of specific and small molecules. In this way, the barrier stops any pathogen from entering the brain. That is to say, that the blood-brain barrier is extremely selective; therefore, medications will not pass through it, so to allow the medicine to enter the brain extracellular fluid, the tight junctions of the endothelial tissue must be disrupted with mannitol.
The right answer is: Bleeding oesophageal varices
Bleeding oesophageal varices occur when swollen veins (varicose veins) of the lower esophagus rupture and bleed.
Oesophageal varices may leak blood and eventually rupture. This can lead to serious bleeding and life-threatening complications, including death. When that happens, it's a medical emergency.
