The answer is a simple radial nervous system.
Echinoderms do not have brains. Around their mouth, they have central rings from which nerves radially run into arms and along the body. Movement is controlled by the branches of those radial nerves.
All of these are the components of the catabolic pathway or using the nutrients to provide energy from it. The breakdown of food molecules begins in the mouth and continues to the small intestine. The nutrients are absorbed through the wall of the small intestine which. The surface of the intestine wall is specially modified (contains a huge number of hair-like structures-microvilli) which increase nutrient absorption. (more area for nutrients to be absorbed). The digestive tract is lined with mucosa which consists of simple columnar epithelial cells. Monomer subunits of the food, like glucose are than absorbed and diffused down a concentration gradient into capillary blood. Glucose is converted into pyruvate molecules through the process of glycolysis. Catabolism ends in the major energy-converting organelle, the mitochondrion, where the ATP is produced.
<span>The correct option is A. Endomembrane system is a series of units that work together to label, package, and transport proteins and molecules. Endomembrane system are found in the endoplasmic reticulum and golgi apparatus. The major components of the endomembrane system are golgi apparatus, endoplasmic reticulum, vessicles, cell membrane and the nuclear membrane. </span>
B
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