The 4th one. Maintaining body temperature and cooling down
        
                    
             
        
        
        
Answer: Option A.
It lowers the head.
Explanation:
The ischial arch is a prominent structure closer to the colliculus seminalis of horse. The ejaculatory duct is lateral to this and correspond to the area of ductus differenc eand vesicular gland opening.
The vesicular glands can be easily catheterized using a small-diammeter, flexible polyethylene catheter or a stylet . The catheter is inserted into the instrument channel of the videoendoscope and serves as a route for direct aspiration of fluid or instillation of pharmacologic solutions for direct treatment.It also helps to guide the scope head into the seminal vesicle .
 
        
             
        
        
        
Mitochondrial DNA is a smaller version of regular DNA; with Mitochondrial only having enough base pairs to create 37 genes. This means that mDNA is was sequenced and is a baseline in phylogenetics.  Your answer is going to be "C"
        
             
        
        
        
Answer:
D) over 90
Explanation:
As we know, hemoglobin is the protein found in red blood cells that is in charge of oxygen transportation, and the relation between the percentage of oxygen that binds to hemoglobin and the partial pressure of oxygen in the blood can be represented through the oxygen - hemoglobin dissociation curve, as shown in the attached image.
As we can see in the image, the curve has a sigmoid shape, and this is due to the allosteric interactions between the subunits of the hemoglobin, which change their conformation with each oxygen molecule that binds in order to increase even more the oxgen affinity. This curve is constantly shifting to the right and to the left depending on the conditions of the blood, like temperature, pH, partial pressure of carbon dioxide and the concentration of diphosphoglycerate (DPG).
When the PO2 is around 70 mmHg, as we can see in the curve, the hemoglobin is saturated around 90% or more, reaching a plateu in the curve where the oxygen is not binding as fast anymore, because there are almost no more free binding sites left in the hemoglobin molecule.