Please help with 3456 Describe two mechanisms of defense oth

Describe two mechanisms of defense, other than movement, in the organisms studied. How is cell shape maintained in the diatoms vs. the dinoflagellates and meme one characteristic that you could observe under the microscope to distinguish between the two? What important ecological role is shared by the macroscopic algae (seaweeds)? What characteristics of complex green algae, such as Chari, have led scientists to conclude that this group is most like the ancestral species giving rise to plants? Describe two mechanisms defense, other than movement, in the organisms studied. How is cell shape maintained in the diatoms vs. the dinoflagellates and name one characteristic that you could observe under the microscope to distinguish between the two? What important ecological role is shared by the macroscopic algae (seaweeds)? What characteristic of complex green algae, such as Chard, have led scientists to conclude that this group is most like the ancestral species giving rise to plants?

Solution

3. Two defense mechanisms other than movement, in the organisms studied include

4. In diatoms, the cell wall forms two thin overlapping shells, epitheca over hypotheca which fit together as in a soap box. Walls are embedded with silica and hence indestructible.

In dinoflagellates, the cell wall has stiff cellulose plates on the outer surface. The nucleus has condensed chromosomes even in interphase. This is called as mesokaryon. Histones are also absent in the chromosomes.

5. At least a half of the total carbon dioxide fixation on earth is carried out by algae through photosynthesis.

Algae are the chief primary producers whish form basis of the food cycles of almost all aquatic animals.

Algae such as porphyra, laminaria are used as food.

Water holding substances like algin and carrageen are produced from brown algae and red algae respectively.

Agar is obtained from gelidium and gracilaria.

6. Green algae are usually green due to the presence of pigments like chlorophyll a and b.

Cell wall is made up of inner cellulose layer and outer pectose layer.

Chloroplasts are discoid, plate like, spiral or ribbon shaped.

Food storage bodies called pyrenoids are present in the chloroplasts. They contain protein and starch.

These characteristics of green algae have led scientists to conclude that this group is most like the ancestral species giving rise to plants.