Regeneration in planarians depends on the presence of stem cells called neoblasts. These cells are distributed throughout the body and, when part of the worm has been amputated, they are activated to reform the tissues that have been removed.
Mitosis in an eukaryotic cell cycle occurs after the G2 phase (option b). This is the final stage of interphase and during this time, the cell continues to grow as well as create new proteins. Successful completion of this phase results in the commencement of Mitosis.
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Cell nucleus chromosome gene nucleotide base subunit atom
Answer:
External respiration: CO2 diffuses into the blood
Explanation:
External respiration is also called the pulmonary gas exchange. It refers to the diffusion of O2 from the air in the alveoli of the lungs to blood in pulmonary capillaries and diffusion of CO2 in the opposite direction from the capillary blood into the alveolar air. External respiration in the lungs is responsible for oxygenation of deoxygenated blood coming from the right side of the heart. The oxygenated blood is then returned to the left side of the heart.