Answer:
mutations in proto-oncogene are generally cancerous while mutation in tumor-suppressor alleles are recessive and result lost of function
 
 
        
             
        
        
        
Answer:
A. The heartbeat can be heard
Explanation:
After the first trimester, during the fourth month, the heartbeat of the fetus becomes loud enough to be heard with the help of a stethoscope placed on the abdomen of the mother. 
From fifth to the seventh month of the development, kicks and jabs are felt by the mother as the fetal legs grow and develops. Languo, a wrinkled pink colored skin covers the fetus. 
Languo is in turn covered with a white greasy substance called vernix caseosa. 
From eighth to ninth months, rotation of the fetus places its head pointing towards the cervix to facilitate childbirth later. 
The development of testes takes place in the seventh month while the body hairs become disappeared in the eighth month.
 
        
                    
             
        
        
        
Where the picture but,The Plasma membrane maintains the homeostasis throughout a cell because it <span>filters what substances go in and out of the cell. </span>
        
                    
             
        
        
        
Answer;
-B3
Explanation; 
Refrigerants are divided into two groups according to toxicity:
-Class A signifies refrigerants for which toxicity has not been identified at concentrations less than or  equal to 400 ppm;  and
-Class B signifies refrigerants for which there is evidence of toxicity at concentrations below 400 ppm. 
They are also divided into three groups according to flammability:
-Class 1 indicates refrigerants that do not show flame propagation when tested in air at 21°C and 101  kPa;
-Class 2 indicates refrigerants having a lower flammability limit of more than 0.10 kg/m3  at 21°C and  101 kPa and a heat of combustion of less than 19 kJ/kg;
-Class 3 indicates refrigerants that are highly flammable as defined by a lower flammability limit of less  than or equal to 0.10 kg/m3  at 21°C and 101 kPa or a heat of combustion greater than or equal to 19  kJ/kg. 
-Therefore; the answer for the above question would be Class B and class 3.
 
        
                    
             
        
        
        
Explanation:
water moves through the hydrosphere in a cycle. Water collects in clouds, then falls to Earth in the form of rain or snow. This water collects in rivers, lakes and oceans. Then it evaporates into the atmosphere to start the cycle all over again