Answer: Proximity to where people live. Convenience is a very important factor to consider when locating a well. Studies have shown that when a water point is located less than 200 meters from a home, people tend to use more water than when the source is farther away.
Explanation:
 
        
                    
             
        
        
        
19. B - mitochondria
20. D - vegetative structure
21. C - inducing a mutation
22. A - phosphates
23. C - fungi
24. A - provides support
25. C - sponges
26. B - opposite charges
27. D - asexual reproduction
28. not sure about this one sorry
29. D - all of the above
30. A - prevents ions and large molecules from passing through the membrane
        
             
        
        
        
Answer:
 It provides a defined order to the succession of organisms. 
Explanation: Relative dating of rocks involves the relative or comparative determination of age with reference to past events. There are several principles involved in carrying out relative dating. Some of these principles are:1. Principle of inclusion2. Principle of inclusion 3. Principle of fossil and fauna succession The Principle of fossil and fauna succession postulates that fossil and fauna succeeds one another in a definite pattern. It is this defined order that we use to achieve relative dating of rocks. Plant and animal remains constitutes the fauna and fossils used in dating the rocks. When we find a particular fossil in a rock, we can place that rock in its appropriate geological time. We can even go further by correlating rock types using their fossil contents.
 
        
             
        
        
        
Answer:
from the intermembrane space to the matrix
Explanation:
In the electron transport chain (ETC), electrons flow from one protein complex to another. However, as this electrons are transfered, protons (H+) is built up from the intermembrane space of the mitochondria to the mitochondrial matrix. 
Hence, according to this question, a proton gradient is formed when hydrogen ions (H+) are moving from the intermembrane space to the matrix of the mitochondrial. 
 
        
             
        
        
        
Answer:
All of these choices are correct.
Explanation:
Cell cycle is the process of growth and division of cell. It comprises of interphase and mitosis. In interphase the cell grows, replicates its genomic content and prepares itself for division. In mitosis the division occurs. 
Cell cycle is controlled by a group of kinases called as Cyclin dependent Kinases (CDKs). They act by phosphorylating their substrates. They are of various types like Cdk1, Cdk2, Cdk4 etc. They become active when they bind to a regulatory protein called cyclin. They are also of various types like Cyclin A, Cyclin B, Cyclin C etc. Level of cyclin and corresponding CDK increases and decreases according to the stage of cell cycle. For example in S phase of cell cycle concentration of cyclin A and E shoots up. CDK2 is able to bind to these cyclin molecules and hence it becomes active. 
Cell cycle has major checkpoints where the condition of cell is analysed before it proceeds to the next stage of cycle. If any abnormality is detected, repair mechanism is activated or the cell is killed. Checkpoints do not allow cell cycle to proceed in damaged cells. 
p53 is a tumor suppressor protein which can halt cell cycle when it detects some abnormality in cell. It usually acts in G1/S checkpoint (before the DNA replication starts in cell) and G2/M checkpoint (before the cell division begins). Hence, all of the above statements are true.