Question

Are the protists a monophyletic group? please discuss this and describe this by drawing a “tree” that would include the diatoms, dinoflagellates, red algae, brown algae, green algae and charophytes. what are the main characteristics of these different groups, i.e., which of these groups have silica in its cell walls? Which has both chlorophyll a and b,which of these is considered in the plantae group but NOT a green plant, etc.?

Answer 1

Protists are not a monophyletic group because there is not one common ancestor that is unique to only the organisms in Kingdom Protista.Compare this with animals which all have one common ancestor or fungi which all have one common ancestor or plants which all have one common ancestor. These three kingdoms are therefore “natural” (monophyletic) groups.Kingdom Protista is an artificial grouping of organisms.

DIATOMS:

SILICA IN CELL WALLS : mainly silica and pectic material.

PRESENCE OF CHLOROPHYLL: chlorophylls a and c

PLANTAE GROUP: no.

DINOFLAGELLATES:

SILICA IN CELL WALLS : absent. cellulose present

PRESENCE OF CHLOROPHYLL: chlorophyll a and c

PLANTAE GROUP: no.

RED ALGAE :

SILICA IN CELL WALLS : absent. inner layer cellulosic and outer pectic.

PRESENCE OF CHLOROPHYLL: chlorophyll a and d

PLANTAE GROUP: yes.

BROWN ALGAE :

SILICA IN CELL WALLS : absent. inner layer cellulosic and outer layer consists of alginic and fusinic acid.

PRESENCE OF CHLOROPHYLL: chlorophyll a and c

PLANTAE GROUP: yes.

GREEN ALGAE :

SILICA IN CELL WALLS : absent. mainly cellulose and pectic material.

PRESENCE OF CHLOROPHYLL: chlorophyll a nad b

PLANTAE GROUP: yes.

CHAROPHYTES :

SILICA IN CELL WALLS : absent,. cellulose and pectic material

PRESENCE OF CHLOROPHYLL: a and b

PLANTAE GROUP: yes.