External respiration is the process of taking oxygen into and expelling carbon dioxide from the body. External respiration is essential for life as it supplies oxygen to extract energy from food via internal or cellular respiration. Additionally, it removes carbon dioxide, which is a waste product of respiration.
The nucleus is a membrane bound structure that contains the cell's hereditary information and controls the cell's growth and reproduction.It is commonly the most prominent organelle in the cell. The nucleus is surrounded by a structure called the nuclear envelope.This membrane separates the contents of the nucleus from the cytoplasm. The cell's chromosomes are also housed within the nucleus.he nucleus is surrounded by a structure called the nuclear envelope. This membrane separates the contents of the nucleus from the cytoplasm. The cell's chromosomes are also housed within the nucleus.
Nucleus The nucleus is the command central of the cell because it contains almost all of the cell's DNA, which encodes the information needed to make all the proteins that the cell uses. The DNA appears as chromatin through most of the cell cycle but condenses to form chromosomes when the cell is undergoing mitosis.