The answer to this question is 1.DNA because RNA is single stranded.
        
                    
             
        
        
        
Answer:
Nervous system: This systems helps the five sense organs (eyes, ears, nose, tongue, skin) which all contain nerves that send messages to the brain about what is happening. The brain produces a response which it sends via other nerves to the muscles.
Digestive system: This system helps to break down food into simpler substances so it can be used and absorbed into the body. It takes place in the alimentary canal (food tube), mainly in the stomach and small intestine. The digested food is absorbed into the blood.
Respiratory System: This system helps take in oxygen and removing waste carbon dioxide. Air enters the lungs by movement of the rib muscles and diaphragm. The oxygen is absorbed into the blood. 
Reproductive system: This helps produce offspring. Eggs are produces by ovaries in a female and the sperm is produced in the testes of a male. They then try and fertilise the eggs. 
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Hope this helped <33
 
        
             
        
        
        
Answer:
precession 
Explanation:
The orbit isn’t the simple ellipse, rather it is one that moves a little, loop after loop. This motion is called precession, and you may have heard about it when astronomers talk about the precession of the orbit of Mercury
 
        
             
        
        
        
Correct matching of invertebrates and its characteristics are as follows:
Sponges are animals which have many cell but no mouth, muscles , heart or brain. They are sessile and can not move from place to place like other animals do, filter feeding animals with an asymmetrical body plan.
Cnidarians are the animals with radial symmetry and stinging cnidocyte cells. These animals consists a special cell cnida which functions in preying catch and defense. example- jellyfish, anemone.
Flatworms are the worm like animal which do not consist a body cavity or coelom. example- fluke and tapeworms.
Roundworms or threadworms are segmented worms that can live in water or land. They consist a body cavity and internal organs. examples- pinworms and hookworms.
Mollusks are the animals which consist mentle, foot and and sometimes a shell. example- octopus, squids. 
Echinoderms are the animals which have radial symmetry and an endoskeleton made out of calcareous plate. These animals live only in marine environment.These animals lack circulatory and excretory systems. 
Arthopods are the animals with jointed legs and an exoskeleton made out of chitin. example- spiders, shrimps and crabs.
 
        
             
        
        
        
Answer:
Sagittal plane, imaginary plane dividing the human body into left and right halves. Sagittaria, a genus of about 20 species of aquatic plants. Sagittarians (disambiguation) Sagittarius Aiolos, a character in Saint Seiya.
Explanation: