Answer:
A
Explanation:
Thick clouds can trap lots of heat. This has a warming effect on earth.
 
        
             
        
        
        
Scientific validity is the applicability of a conclusion drawn in the context of a scientific experiment to the world at large.
        
             
        
        
        
Answer:
olecules can diffuse across membranes via transport proteins, or they can be aided in active transport by other proteins. Organelles such as the endoplasmic reticulum, Golgi apparatus, mitochondria and peroxisomes all play a role in membrane transport.
 
        
                    
             
        
        
        
Answer: 4 Guanines
Explanation: Following Chargaff's ratio that describes the ration of purines to pyrimidines as 1:1, if there are 23 purines, it follows that there should be 23 pyrimidines; 15 Thymines should therefore be hydrogen bonded to 15 Adenines by complementary base pairing.
We are then left with 8 nucleotides composed of guanines and cytosines in complementary base pairs. This means that half that number (4) should be guanines and the rest cytosines.