Answer:
 Neutrophils and Macrophages
Explanation:
 
        
             
        
        
        
Answer:
Rosalind's x-ray showed that the ladders of nucleotides were inside a double helix. 
Watson and Crick built models with the ladders on the outside. 
 
        
                    
             
        
        
        
Answer: taking deep breaths 
Explanation:
Apart from reminding oneself that you are prepared for the presentation. You can carry out a physical exercise like the breathing exercise by taking several deep breaths and exhaling to reduce nervousness. Also you should be mindful that the audience is there to hear you and not to judge you. In that way you can ease out tension.