Krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus<span>.</span>
        
             
        
        
        
Answer:
Attached is an image go help you with this. 
 
        
             
        
        
        
Fish don't have ears we can see but they have ear parts inside their heads. They pick up sounds in water through their bodies.
        
             
        
        
        
Answer: Sea walnuts are marine invertebrates. They belong to the genus Mnemiopsis.
Explanation:
These animals have stinging tentacles like jelly fish and they often cast up or come to the sea shores where if they come in contact with humans can harm them by stinging. 
The barrier if kept along the side of the sea shore and not allowing humans to reach to the shore can help in preventing the harm from these animals. The introduction of the predatory animals in the sea can also help in reducing their population. 
The three benefits for removing the sea walnut: 
1. The population of other species will increase as sea walnut is an invasive species.
2. The balance of the marine ecosystem can be maintained.
3. Humans can be protected from the harm caused by these animals. 
 
        
             
        
        
        
Answer:
The respiratory system is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies greatly, depending on the size of the organism, the environment in which it lives and its evolutionary history. In land animals the respiratory surface is internalized as linings of the lungs. Gas exchange in the lungs occurs in millions of small air sacs called alveoli in mammals and reptiles, but atria in birds. These microscopic air sacs have a very rich blood supply, thus bringing the air into close contact with the blood. These air sacs communicate with the external environment via a system of airways, or hollow tubes, of which the largest is the trachea, which branches in the middle of the chest into the two main bronchi. These enter the lungs where they branch into progressively narrower secondary and tertiary bronchi that branch into numerous smaller tubes, the bronchioles. In birds the bronchioles are termed parabronchi. It is the bronchioles, or parabronchi that generally open into the microscopic alveoli in mammals and atria in birds. Air has to be pumped from the environment into the alveoli or atria by the process of breathing which involves the muscles of respiration.
Explanation: