Answer:
La pata de un pato y la aleta de un pez son en ambos casos son elementos que les permiten tanto al pato como al pez moverse, además de sus funciones de estabilidad. La aleta de una ballena y el brazo del ser humano, sucede lo mismo que en el caso anterior. En el caso de la aleta de la ballena, es como la aleta del pez. En cuanto al brazo del ser humano permite realizar movimientos que contribuyen al desarrollo de sus funciones, como por ejemplo, agarrar distintos elementos. La pelvis reducida de los cetáceos no tiene actualmente ninguna función.
Explanation:
La pata de un pato es una extremidad que por su estructura le permita nadar perfectamente. En cuanto a la aleta de los peces y ballenas, es una parte de estos animales formada por tejido conjuntivo. Pueden tener distintos tamaños y su principal función no sólo es permitir el movimiento sino también la estabilidad. En cuanto a la pelvis reducida de los cetáceos era algo que tenía sentido en especies de antaño. Durante la evolución, su utilidad de fue perdiendo, como podría mencionarse el ejemplo en los humanos de las muelas de juicio.
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.
Answer:
b. such as RNA and DNA
Explanation:
DNA and RNA represent essential molecules present in all organisms. These nucleic acids (DNA and RNA) are composed of large chains of nucleotides that function to synthesize proteins required for cellular processes and to produce cell structures. Both RNA and DNA are highly stable biomolecules capable of storing and transmitting genetic information, which has been a requisite for the evolution of modern cells. Moreover, it is important to note that DNA is a double-stranded molecule and therefore it is more stable than single-stranded RNA.
Answer:
is hypotonic to the protozoans
Explanation:
The constant influx of water from the outside environment of the cell tells that <u>the environment is hypotonic to the cell</u>.
<em>A hypotonic environment is one with a lower solute concentration than the cytosol. Hence, water osmotically moves from the environment into the cells of the protozoans. The water needs to constantly be removed from the cells, otherwise, they will become turgid and lyse away their contents. </em>
