Yes they are alive in numbers today and they are known as one of the most top shark killers there are, other than the great white shark and killer whales. *there is a pic below of the shark, I take no credit for it, I just found it off google.
 
        
        
        
Answer:
To observe the cheek cell,
- 
Take a tooth pick use its blunt side to scrap inside the mouth.
- You will see some deposition on the blunt side of tooth pick, make a smear on the clean slide in the center using that tooth pick.
- Add a drop of methylene blue solution and place a coverslip, make sure that bubbles are avoided i.e. coverslip should be placed in the inclined manner.  
- Remove the excess solution and observe it under the microscope first under 4X and then under 10X. 
Observation:  
- The cells observed are squamous epithelial cells. The small blue dots seen inside will be the bacteria from our teeth and mouth.
 
        
             
        
        
        
Answer:
Closed the first one
Explanation:
In amphibians, reptiles, birds, and mammals, blood flow is directed in two circuits: one through the lungs and back to the heart, which is called pulmonary circulation, and the other throughout the rest of the body and its organs including the brain (systemic circulation). 
most mammals, have closed cardiovascular systems. The two main circulation pathways in invertebrates are the single and double circulation pathways.
 
        
             
        
        
        
1. form on the surface    2. form below the Earth's crust    3. cool quickly    4. cool slowly    5. have large mineral crystals    <span>6. have small mineral crystals
those are your choices right? if so then...
1, 3, 5 are your answers
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<span>The Growth hormone (GH) is of greatest importance in human development. It is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans. GH is produced by the pituitary gland, and it also helps to regulate body composition, body fluids, and muscle and bone growth.</span>