This law states an organism has two different alleles for a trait and the allele that is expressed in the phenotype, masking the expression of the other allele,is said to be dominant. The allele whose expression is masked is said to be recessive.
        
                    
             
        
        
        
Answer:
Internal Fertilization: Mammals,birds and reptiles in them the mode of fertilization is internal
External Fertilization: Amphibians and fishes used external fertilization.
Egg laying Animals;Birds,reptiles and some mammals platypus lays eggs.
Explanation:
Fertilization is a process in which a female egg (Ovum) and male egg (sperm) unite to form a zygote.A zygote is a fertilized egg which grows within an embryo.The process of fertilization is important in eukaryotes such as animals, humans,birds and plants. Fertilization divides a cell into many daughter cells by the process of mitosis and meiosis.It doubles the chromosome numbers.Fertilization are of two types internal and external.
 
        
             
        
        
        
Answer:
2nd one is the most realistic of what occurs in ecosyystems