Why does a euglena has a flagellum that allows it to move?

Euglena move from one place to another like an animal. When they manufacture their own food, they have to move to such an area where they can receive required amount of sunlight. There are two features on its body that facilitate in its movement. The most important is the flagellum, which is a long whip-like appendage attached to the body. It turns and twists in the water in order to push the body through the water. The other physical feature that plays a vital role in giving a sense of direction to its movement is the eyespot, also located at the anterior of its body. It is a light-sensitive, pigmented organelle which is capable of detecting sunlight. Thus, it orients the movement towards the direction of light, where they can collect sunlight required for making food.The ability to move plays a significant role in vital life processes of Euglena, such as the synthesis of food. Hope that helps ;)

The truman doctrine was an american foreign policy whose stated purpose was to counter soviet geopolitical expansion during the cold war. it was announced to congress by president harry s. truman on march 12, 1947, and further developed on july 12, 1948, when he pledged to contain threats to greece and turkey