Comparing different types of Organisims

Question 1

Unicellular Organisims

Answer 1

Unicellular organisms are made up of one cell that has to carry out all metabolic processes. This cell could be either prokaryotic or eukaryotic.

Cells of unicellular organisms have a high SA:V, which allows efficient movement of substances into and out of the cell.

Question 2

Colonial Organisms

Answer 2

Colonial organisms are composed of individual cells living together in a colony.

All cells in the colony are capable of carrying out all of the metabolic functions necessary for life; however, simple specialised cells can be present in the colony to improve the efficiency of functioning of the organism.

Evolutionary link between unicellular and multicellular organisms.

Question 3

Multicellular Organisms

Answer 3

Multicellular organisms are composed of many different types of specialised cells.
Similar specialised cells are grouped together and perform specific functions that combine for the efficient functioning of the organism.

Individual cells in multicellular organisms cannot live independently of each other.

Question 4

Example of a colonial organisim

Answer 4

Volvox

Question 5

Stem Cells

Answer 5

Undifferentiated cells with no specialised structure or function.

Stem cells can be either embryonic or adult stem cells.

Type of cell formed is determined by the location of undifferentiated cells in the organism and the specific genes that are switched on.

Question 6

Specialised Cells

Answer 6

Specialised cells are formed when differentiation of the stem cells occurs and they develop suitable structural features that allow them to carry out their specific functions.

Question 7

Specialised Cells in Plants

Answer 7

In plants, specialised cells are formed by the differentiation of meristematic tissue.

Question 8

Example - Red Blood Cells

Answer 8

They are very small and have a particular shape to increase surface area to volume ratio for the exchange of oxygen.

They lack a nucleus and organelles, enabling more haemoglobin to be carried in the cell.

Question 9

Cell Structure and Function

Answer 9

Cells whose function involves exchanging substances with the external environment will probably be flat and long to increase surface area to volume ratio, or have many folds to increase surface area.