Answer:
 500
Explanation:
Mutation rate is largely known as changes that occur in the frequency of a particular gene over an extended period of time 
So given that; 
the  mutation rate of a particular gene = 1 × 10⁻⁶
The expected mutations after 500 million sperm are examined will be:
= (1 × 10⁻⁶)×(500,000,000)
= 500
Thus, The expected mutations  = 500
 
        
             
        
        
        
Answer: A sum total of all living and non-living elements and their effects which influence human life is known as environment. An environmental aspect is an element of an organization's activities, products, and services that can interact with the environment. These can include discharges to water, emissions to air, waste and use of natural resources and materials.
2.Answer: 1.  
Environment plays an important role in healthy living and the existence of life on planet earth.
2. Earth is a home for different living species and we all are dependent on the environment for food, air, water, and other needs. 
3.Everything that surrounds us constitutes our environment.  .
4.  The environment plays an important role in the healthy living of human beings.
 
        
             
        
        
        
Gonads are the reproductive organs that produce gametes. 
Gametes are also known as sex cells. They are produced by the gonads. In males, the gonads are the testes. The gametes that are produced by males are called sperm cells.  In females, the gonads are the ovaries. The gametes that are produced by females are called egg cells.  
        
             
        
        
        
Answer:
B. an asteroid belt lies between them.
Explanation:
The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets.