Body design and reproduction

The idea

The mode of reproduction depends on body design: organised multicellular organisms cannot divide cell-by-cell, so reproduction is the job of a specific cell type able to grow, proliferate and make other cell types.

Cut a cell at a time?

A human body is not a random heap of cells. Cells form tissues, tissues form organs, and organs sit at definite places.

Can such a body reproduce by splitting cell by cell?

• No, that would be impractical
• Yes, splitting cell by cell is easy
• Yes, any single cell can do it alone

Compare the bodies

Open each tab.

The body design decides

The mode of reproduction depends on the body design. Organised multicellular organisms cannot divide cell by cell. So reproduction is the job of one specific cell type, which can grow, multiply and make other cell types.

The mode of reproduction depends on body design. Organised multicellular organisms cannot divide cell-by-cell, so reproduction is the job of a specific cell type able to grow, proliferate and make other cell types.

Notes

The mode of reproduction depends on body design. In organised multicellular organisms a specific cell type that can grow, proliferate and make other cell types does the job.

Check yourself

Why can organised multicellular organisms not simply divide cell by cell?

In such organisms, reproduction is the function of …

What must the cell type that does reproduction be able to do?

The mode of reproduction of an organism depends on its …

• Their cells are organised into tissues and organs at definite positions — correct. Yes!
• Their cells are too small to see. The reason in the book is the careful organisation of cells into tissues and organs, not the size of the cells.
• They have only one kind of cell. Such organisms have many cell types, each with a specialised function.
• every cell at the same time. Following the general pattern, reproduction is the function of a specific cell type.
• a specific cell type — correct. Yes!
• a random collection of cells. The book says these organisms are not a random collection of cells.
• Only stay as one cell and do nothing else. The book says it must be capable of growing, proliferating and making other cell types under the right circumstances.
• Turn into the same cell every time. It must be able to make other cell types, so that the whole body can be formed.
• Grow, proliferate and make other cell types — correct. Yes!
• body design — correct. Yes!
• colour. The book says the modes of reproduction depend on the body design of the organisms.
• name. The mode of reproduction depends on the body design, not on the name.