Answer: According to Darwin theory of evolution the struggle for existence is considered as major part for competition among living things.
Explanation:
Coexisting species that belong to the same genera compete for same kind of resources for their survival. Some phenotypic variations gives an survival advantage over others. The superior ones dominate the inferior ones and compete for resources. The one who receives the resources like mates, food, shelter, and others the chances of survival also increases considerably.
Answer:
Option-D, a segment of DNA
Explanation:
A gene represents the particular segment of DNA which contains the instruction for the trait of an organism. The nucleotide sequence present in the segment provides the instruction in the form of codons.
The gene is present in the form of its alternative form called alleles which are located on the chromosomes at locus. The alleles represent the variants of the gene and therefore controls the two variety of a single trait.
Thus, Option-D is correct.
Meiosis - the cells divide to produce 4 haploid cells
In 1665, Robert Hooke observed D. Cell Walls through a microscope!
