Answer:
a, b, d, and f.
Explanation:
<em>The periwinkle snails feed on plants. Consequently, they are said to herbivorous and heterotrophic since they cannot manufacture their own foods. They are also referred to as primary consumers because they directly feed on plants without any other nutritional option. They, therefore, occupy the second trophic level on a typical food web. </em>
The correct options are a, b, d, and f. 
 
        
             
        
        
        
Answer:
A Recessive
Explanation:
Generally, there are two types of disorders, progressive and recessive. When something is recessive, it is not a dominant gene. The reason why sickle cell anemia is classified as a recessive disorder is because it only affects some people, but it does not affect all those who share DNA. Hope this helps! 
 
        
             
        
        
        
The answer is plankton are floaters. Plankton and nekton are both marine aquatic organisms. The main difference between the two is that plankton tend to float and be carried by water currents while nekton are organisms that swim against the current of the water. Plankton are passive swimmers while neekton are active swimmers.
        
                    
             
        
        
        
Answer: 101 neutrons
An element's atomic number is the number of protons in its nucleus. X has 52 protons. The mass number is simply the number of protons AND neutrons in the nucleus. Since 52 is given, it's correct to assume that the remainder consists of neutrons. 153-52 will give you the number of neutrons. 
Hope this helps! :)