Question

PLEASE PROVIDE SHORT ANSWERS

5. List 3 characteristics shared by all complex multicellular organisms, and explain the differences between simple multicellular organisms and complex multicellular organisms.

6. Describe the characteristics of the amniotic egg and explain why this type of egg was so important in the evolution of terrestrial vertebrates.

7. Explain why diffusion limits the size of cells and organisms, and describe how multicellular organisms solve this problem.

8. Define endotherm and ectotherm, and explain the advantages and disadvantages of each.

9. Define mass extinction, and describe what happens after a mass extinction in terms of speciation among the surviving organisms.

Answer 1

You have asked multiple questions here. As per Chegg Q&A Guidelines, I am answering only the first question that is Question 5.

Evolutionary theory suggests that all life forms came from a common ancestor. This provides the substance that all multicellular and unicellular organisms arose from a common ancestor. Unicellular life forms are the most primitive ones. Simple multicellular life forms simply exist as colonies when the need arises. However, they also have phases where the cells exist independently of the others and often compete with other cells for resources. This simple form of multicellular life exhibit the benefits of division of labor.

Natural selection and fitness advantage provided by these life forms led eventually to the formation of true multicellular life forms like poriferans, simple fungi and algae. There are several commonalities shared by these diverse life forms. These include:

1. Division of labour wherein certain tissue types are specialized at performing a specific function.

2. All multicellular life-forms we know of are eukaryotes which have membrane-bound organelles with the genomic DNA enveloped inside a nuclear membrane. This allows for efficient localization of proteins and energy resources.

3. Complex multicellular organisms also exhibit systems and organs that are specialized at these tasks. They also have co-ordination systems like hormonal and nervous systems that allow for homeostasis and proper functioning of the organism based on the environmental needs.