W a t e r ahhhh 8228c+x Skansen 2828
        
             
        
        
        
Answer:
Oxygen
Explanation:
A waste product of photosynthesis organisms need for cellular respiration is oxygen. We breathe out carbon dioxide and plants use carbon dioxide during photosynthesis and in return they give us oxygen which is their waste product. 
 
        
             
        
        
        
Outer core is the answer - Appex
 
        
             
        
        
        
Autotroph is an organism that can produce its own food using water ......
But because Autotrophs produce their own food , they are sometimes called producers .
So you can say Autotroph or producer .
Is that help my friend ?
        
             
        
        
        
The blood vessels farthest from the heart must have valves.
The valves which are present in the blood vessels prevent the backflow of the blood back into the specific organ.
There are different valves present in the heart are:
- The tricuspid valve is situated between the right atrium and right ventricle.
- The pulmonary valve is between the right ventricle and the pulmonary artery.
- The mitral valve is between the left atrium and left ventricle.
- The aortic valve is between the left ventricle and the aorta.
Other vales which are present in the blood vessels are in leg. Leg veins do require the valves. If not present the blood will go back down into the feet because of the gravity. Thus there are various valves present in the leg veins. 
Valves in veins are bicuspid, meaning they have two flap-like structures that regulate blood flow in the vein.
To know more about the Valves, refer to this link:
brainly.com/question/12926213
#SPJ4