Answer:
The correct answer is -
Euglena - single-cell organism
Onion bulb - organ
Blood - tissue (connective tissue)
Explanation:
The level of organization of an organ, or organism could be cellular level, tissue level, the organ level, organ system, or a complete organism. These levels are formed by assembling the lower level of the organization.
Euglena is a single-cell eukaryotic organism found in freshwater. These organisms have a very simple level of an organism which is cellular level. The onion bulb is the organ of the onion plant composed of shortened, compressed, underground stems (tissue) that are an organ-level organization.
The blood is considered as connective tissue due to the blood cells present in the matrix called plasm thus, blood is connective tissue.
Scientists rely on embryological development patterns and adult body plans for all animals in order to classify animals. The correct option among all the options that are given in the question is the third option or option "c". It is the work of the biologists to classify animals and put them in order for studying them easily and in a group.
Genetic variation allows for a greater chance of a population surviving. For example, if a plant species acquires a disease, without genetic variation the disease would just keep getting passed on to the next identical organism and the population would decline and eventually die. But genetic variation prevents that from happening, because you have so many other species in the ecosystem, and genetic variation is a product of sexual reproduction meaning that the offspring of the diseased plant has a possibility of not inheriting the disease.
