They make up structural parts of cell membranes
        
                    
             
        
        
        
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:
TCTAGGA
Explanation:
The deoxyribonucleic acid (DNA) molecule consists of two single-strands, which are composed of four different types of nucleotide bases: Adenine (A), Thymine (T), Guanine (G) and Cytosine (C). These two DNA strands run in an anti-parallel direction to each other. According to the base-pairing rules, Adenine always pairs with Thymine, while Guanine always pairs with Cytosine. In DNA, Thymine and Adenine form two hydrogen bonds between them, while Guanine and Cytosine form three hydrogen bonds between them.
 
        
             
        
        
        
Answer:
a. transcription
Explanation:
<em>Sugar transport in phloem is referred to as pressure flow and it involves the movement of sugar through the phloem vascular tissue from the regions where sugar is synthesized (by photosynthesis) to other parts of the plant's body that require sugar.</em>
The parts of plants where sugar is synthesized (usually the leaf) is known as sugar source while the parts where they are transported is referred to as the source. Sources are usually areas of of high osmotic concentration and high water pressure while sinks are usually areas of low osmotic concentration and low water pressure.
<em>Hence, sugar transport in the phloem can be said to be influenced by the rate of sugar production at the source (rate of photosynthesis), turgor pressure as well as sugar concentration in sinks and sources.</em>
The only option that has no known effect on sugar transport in the phloem is transcription. 
The correct option is a.
 
        
             
        
        
        
Answer:
Tundra
Explanation:
Permafrost is a layer just beneath the surface of the ground that never thaws.