Answer: Straightening a limb after flexion is an example of extension. Extension past the regular anatomical position is referred to as hyperextension. This includes moving the neck back to look upward, or bending the wrist so that the hand moves away from the forearm.
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A sperm cell's structure is very specialized. Its flagellum is used for locomotive function, to rapidly swim directly through the egg cell. While the cytoplasm, it contains organelles, such as the Mitochondria, wherein respiration occurs, to release the energy needed for the sperm's journey towards the egg cell. Sperm cells, contain special enzymes known as acrosomes, this special enzymes allows the sperm to break through the cell membrane of the egg.
        
             
        
        
        
Virbrant energy it is used also make glucose
        
             
        
        
        
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D. A joint in the spine that is slightly movable and separated by cartilage.
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Phenotype is referred to as the expressed trait that is caused by a certain combination of alleles. 
<h3>What is phenotype?</h3>
Phenotype is referred to as the expressed trait that is caused by a certain combination of alleles. We will recall that the HbS allele is responsioble for the anemia that results from sickle shaped red blood cells.
This phenotype is both harmfull and benefical in the sense that it leads to the agglutination of the red blood cells in individuals that have this phenotype and eventual crisis. Also, it is beneficaila in that nthose who possess this phenotype do not suffer from malaria in the tropics.
Learn more about HbS allele: brainly.com/question/12347919