Explanation:
During telophase II and cytokinesis, chromosomes arrive at opposite poles and begin to decondense; the two cells divide into four unique haploid cells.
In meiosis the are two divisions. The division of the original cell results in two daughter cell. Those two cells divide to produce 4 haploid cell in total.
Answer:
In muscles contraction the correct order of the steps are: A (Nerve impulse reaches the muscle), B (Action potential travels down T-tubules), C (Calcium binds to troponin), D (Tropomyosin moves).
Explanation:
Skeletal muscle contractions are based on different physiological and biochemical phenomena that happen in every cell. These phenomena are due to stimulation produced by somatic motor neurons, which axons get in contact with muscle fibers through a neuromuscular synapse. In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When an action potential is originated in the central nervous system, it travels to the somatic motor neuron membrane: the muscle fiber, and activates the calcium channels releasing it in the neuron. Calcium makes vesicles to fuse with the membrane and release the neurotransmitter named acetylcholine (Ach) into the synaptic space in the juncture. Then, Ach binds to its receptors on the skeletal muscle fiber. This causes the ion channels to open, and positively charged sodium ions cross the membrane to get into the muscle fiber (sarcoplasm) and potassium get out. The difference in charges caused by the migration of sodium and potassium makes the muscle fiber membrane to become more positively charged (depolarized). The action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane, that make the calcium be released into the sarcolemma. At this point, tropomyosin is obstructing binding sites for myosin on the thin filament. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin binds to the uncovered actin-binding sites, and while doing it ATP is transformed into ADP and inorganic phosphate. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
Answer:
Un ecosistema esta formado por facotres abioticos y bioticos.
Los factores bioticos son aquellos que presentan signos vitales, es decir que cumplen con la vida, metabolismo, respiracion, entre otras funciones vivas.
Los factores abietos son aquellos que no tienen vida pero con los que los factores bioticos intercambian energia, un ejemplo de esto son las rocas, los vientos, los sedimentos, la tierra fertil.
Los factores bioticos serian los organismos vivos como los animales, que al funcionar como sistemas abiertos de intercambio de energia constante mantienen un equilibrio fisico biologico con los factores bioticos.
Explanation:
Los ecosistemas cumplen con una cadena que no debe romperse ni faltar ningun eslabon, si esta continuidad se interrumpe con la extincion de una especie como animal o vegetal el ecosistema variará, y cambiara toda su conformacion.
Es un conjunto de factores bioticos y abioticos en armonia que se complementan e intercambian energia entre si de manera ordenada en eslabones, si uno de estos eslabones se rompe, se extingue, o se modifica por intervencion del hombre u otros factores TODO el escosistema se verá modificado o afectado.
