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.
Answer:
The answer is c.
Explanation:
Age structure data can include all of these aspects except for c I believe.
The central nervous system (CNS), which is made up of the brain and the spinal cord, and the peripheral nervous system (PNS), which is comprised of nerves and ganglia (small concentrations of grey matter).
The brain sends messages to the peripheral nerves in the body via the spinal cord, these have control of muscles and internal organs.
Answer:
The correct answer will be option-E.
Explanation:
Chordae tendinae are the string-like structure in the heart which is composed of dense regular connective tissue called collagen and elastin proteins. They arise from the papillary muscles of the heart and branches out in the ventricle portion of the heart.
These play an important role in the closure of the AV valves to prevent the backward flow of the blood to the atria during ventricular contraction by holding cusps of the valve into the dome-shaped structure.
Thus, option-E is the correct answer.
Answer: existence of a particular species is completely wiped out from the planet
Explanation: Extinction means that the existence of a particular species is completely wiped out from the planet. It is an irreversible form of damage, since neither a single male and female species member is present to procreate. Endangered, on the other hand, means that a species is nearing extinction.
