He labeled the protein of bacteriophages with radioactive sulfur and their DNA with radioactive phosphorus. The bacteriophages were allowed to infect bacteria.
 
        
             
        
        
        
Answer:
Active transport necessary for the sodium-potassium pump to work because  It allows sodium and potassium to move against their concentration gradient. 
Explanation:
The transport of sodium ions outside the cell and potassium ions inside the cells is called active transport that requires the ATP hydrolysis. ATP provides the energy required for this procedure. This sodium-Potassium pump works to move the ions against their concentration gradient to keep the sodium concentration low inside the cells and potassium concentration high inside the cells. 
 
        
             
        
        
        
Answer:
First law of thermodynamics is the conservation of energy states that energy is not created and not destroyed but only can be stored.
Thermodynamics second law states that total entropy of a system increases from lower to higher system and some of the energy is always wasted during the work done.
In the food chain plants are the producers which accept light energy and stored in the form of chemical energy and energy flow to the herbivores and higher trophic levels in the chemical form only and no new energy is created in between the chain (Fisrt law of thermodynamics). Heat is generated during respiration by plants and animals (wasted energy) and entropy also increases with the increase in level of the pyramid of energy (Second law of thermodynamics).
 
        
             
        
        
        
Answer:
dependent variable
Explanation:
In an experiment, a line graph can be used to display the results of the experiment. A line graph, which posseses two axis namely: x-axis or horizontal axis and y-axis or vertical axis, can be used to show the relationship between the independent and dependent variables in an experiment. 
The independent variable, which is the variable subject to change is displayed on the X-axis while the dependent variable is displayed on the vertical or Y-axis.