Question

Which of the following statements about Euglena is correct?
A. Euglena is a flagellate organism.
B. Euglena when placed in continuous darkness,loses its photosynthetic activity and dies.
C. The pigments of Euglena are quite different from those of green plants.
D. Euglena is a marine protist.

Answer 1

Hint: These are unicellular organisms which are autotrophic and heterotrophic in nature and are economically important.

Complete Answer:
- The euglena belongs to the phylum Euglenozoa. The euglena species Euglena gracilis is a model organism, used extensively in the laboratory.
- These are the organisms which can produce their own food via photosynthesis and also can consume food because they are heterotrophic organisms too. Therefore they will not die even if placed in the darkness continuously.
- The euglenas appear typically green because of the presence of chloroplasts, but some of the species appear red in color due to presence of carotenoids in large amounts. The colorful euglenas are present in huge populations congregating on brackish ponds or lakes, it looks like red or green "blooms" across the water. The pigments of the euglena are similar to that of higher plants.
- Euglenas are normally found majorly on water. It forms a green or red film over top of it. They are good indicators of water pollution.
- They bear unique structures such as flagella, eyespot, contractile vacuole and chloroplast. Light sources for photosynthesize are detected with the help of eyespot. The contractile vacuole removes excess water from organisms.
- Euglena shows characteristics of both plants and animals. They have flagellum which are long, whip like structures on its front end. These structures twirl like mini motors on boats propelling through water, thereby helping in the movement. A stiff pellicle is present outside the cell membrane helps euglena retain its shape. The flagellum moves back and forth which beats the motion in water. This allows flagellum to propel euglena through water. Pellicle is flexible that allows Euglena to scrunch up and elongate, so it moves like an inchworm.

Therefore, the correct answer is option A. Euglena is a flagellate organism.

Note: Euglena without contractile vacuoles essentially continue to take in water by osmosis and result in too much water in the cell that leads to cell burst.