Turn the revolving turret (2) so that the lowest power objective lens (eg. 4x) is clicked into position.  
Place the microscope slide on the stage (6) and fasten it with the stage clips.  
Look at the objective lens (3) and the stage from the side and turn the focus knob (4) so the stage moves upward. Move it up as far as it will go without letting the objective touch the coverslip.  
Look through the eyepiece (1) and move the focus knob until the image comes into focus.  
Adjust the condenser (7) and light intensity for the greatest amount of light.  
Move the microscope slide around until the sample is in the centre of the field of view (what you see).  
Use the focus knob (4) to place the sample into focus and readjust the condenser (7) and light intensity for the clearest image (with low power objectives you might need to reduce the light intensity or shut the condenser).
When you have a clear image of your sample with the lowest power objective, you can change to the next objective lenses. You might need to readjust the sample into focus and/or readjust the condenser and light intensity. If you cannot focus on your specimen, repeat steps 3 through 5 with the higher power objective lens in place. Do not let the objective lens touch the slide!
When finished, lower the stage, click the low power lens into position and remove the slide.  
Your microscope slide should be prepared with a coverslip over the sample to protect the objective lenses if they touch the slide.  
Do not touch the glass part of the lenses with your fingers. Use only special lens paper to clean the lenses.  
Always keep your microscope covered when not in use.  
Always carry a microscope with both hands. Grasp the arm with one hand and place the other hand under the base for support.
 
        
             
        
        
        
The answer is A The amino acid inactivates the repressor
        
             
        
        
        
Answer:
Explanation:
Although protons resemble other positive ions such as Na+ and K+ in their movement across membranes, in some respects they are unique. Hydrogen atoms are by far the most abundant type of atom in living organisms; they are plentiful not only in all carbon-containing biological molecules, but also in the water molecules that surround them. The protons in water are highly mobile, flickering through the hydrogen-bonded network of water molecules by rapidly dissociating from one water molecule to associate with its neighbor, Protons are thought to move across a protein pump embedded in a lipid bilayer in a similar way: they transfer from one amino acid side chain to another, following a special channel through the protein.
 
        
                    
             
        
        
        
Prokaryotic cells do not have membrane bound organelles and eukaryotic cells do have membrane bound organelles
        
                    
             
        
        
        
Answer:
It means one trait does not influence the expression of the other. Example is given in the explanation section.
Explanation:
A trait is the phenotypic characteristics an organism possesses. It is determined and controlled by genes. According to Mendel, an organism receives two forms of every gene called ALLELE. Each allele of a gene encodes a different trait. 
Mendel, in his law of independent assortment stated that the inheritance of a trait encoded by the alleles of one gene does not influence the inheritance of another trait encoded by the alleles of another gene. A trait is said to be independent of another if it doesn't influence the expression of the other trait. 
An example is the seed colour and seed shape trait in a plant. The seed colour trait is encoded by a certain gene and its expression and inheritance is independent of the seed shape trait encoded by another gene.