Once the Earth was full of water (ocean) after volcanic activities the mainland became land ( sorry about my english i am hungarian and i am still learning the language )
Circulatory and Respiratory systems working together to provide body with oxygen.
Ans.
A monohybrid cross can be defined as 'a cross between two individuals having different copies of a chromosome or gene of interest, which is responsible for variations in a single trait.'
These variations in a single trait are controlled by two or more alleles for a single chromosomes. For example, a cross between tall pea plant and dwarf pea plant to study the inheritance of plant height.
Thus, the correct answer is 'option). they differ in a single trait.'
Organisms that reproduce sexually produce sex cells, or gametes, that carry a single set of chromosomes, the haploid number for the species. In contrast, body, or somatic, cells are the regular cells that form the organism’s tissues and organs. Somatic cells of sexual organisms have the diploid number of chromosomes, one set from each parent. Both cell types undergo mitosis, but only the primary reproductive cells, or gametocytes, also undergo meiosis.