Answer: A small middle portion of the sperm contains the mitochondria. The tail of the sperm, sometimes called the flagellum, is a slender, hairlike bundle of filaments that connects to the head and middle portion. The tail gives the sperm cell movement. It whips and undulates so that the cell can travel to the egg.
Lions and tigers competing for an antelope.
Answer:
Blood clothing is an example of positive feedback.
This type of feedback mechanism is useful to the body because it multiplies the factor that intervenes in clotting accelerating the process.
If a toxin affects the molecules that signal for platelets the feedback will not be effective enough to produce clotting and the body will keep bleeding.
Explanation:
Blood clotting is an example of positive feedback due to the fact that when the vascular endothelium is damaged platelets will go to this area and activate themselves once they are in contact with the collagen fibers of the damaged structure. When the platelets are activated they will release the contents that is stored in their granules. One of the contents is a Gq-linked protein receptor cascade, that will increase the concentration of calcium in the platelets. Calcium activates protein kinase C, which, in turn, activates phospholipase A2 (PLA2). PLA2 will modifies an integrin membrane increasing its affinity to bind fibrinogen. The activated platelets change their shape , and the fibrinogen cross-links with the integrin membrane aiding in the aggregation of adjacent platelets. After this the coagulation cascade takes place. there are two pathways the extrinsic and the extrinsic one.
The extrinsic pathway will be activated due to tissular factor released by the platelets and the intrinsic pathway will be activated due to endothelial collagen. The final product of both pathways is factor x.
Factor x will transform prothrombin into thrombin will activate the conversion of fibrinogen into fibrin. Thrombin will form a net of fibrin that will the clot.
A cascade reaction is useful because every component of the cascade are related making a quick reaction once that one of then is activated and can activate other or more factors.
If a toxin affects the molecules that signals for platelets, platelets will not go to the damaged area and in consequence there will not be thrombin and fibrin to form the clot together with platelets.
Cladistics is based on the shared characteristics between organisms and their network of evolutionary relationships
Answer:
<em>If all variation among individuals in a population is due to differing genotypes alone, heritability is 100% and the slope of the line used to measure it is 1.</em>
Explanation:
If the genes play no role in the variation among organisms of a species, then the heritability will be zero percent. Hence, if all the variations among individuals of a population occur due to the differences in the genotype, hence the heritability will be 100%. This is because genes are the hereditary molecules and the genotype of an organism comprises of the different genes present in an organism.
