The main molecule found in nucleus is called DNA(deoxyribonucleic acid). This molecule is made of subunits called nucleotides. A nucleotide is made of a nitrogenous base that can be adenine, thymine, guanine or cytosine; a five carbon sugar called deoxyribose and a phosphate group. This molecule controns protein synthesis. Proteins are crucial to the cell's function.
The excretory and urinary are not the same because the excretory system is collective for all system performing the function of eliminating waste from the body like excess water,urea, carbon dioxide and lactic acid but the urinary system focuses on removal of excess water and urea from the body
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Answer:
Mechanical incompatibility.
Explanation:
Mechanical incompatibility: occurs when species cannot mate because their reproductive structures are incompatible – In animals with internal fertilization, male and female sexual organs may not fit together – For example, snails of species whose shells have left-handed spirals may be unable to copulate successfully.
Mechanical incompatibility of male and female genitalia is common in animals with internal fertilization. However, our knowledge regarding the precise mechanisms is limited.
