Question

In dinophyceae, the two flagella are
A. Anterior
B. One transverse and other vertical
C. Lateral
D. Posterior

Answer 1

Hint: The Dinophyceae are a class of Pyrrophyta which comprises of algae that are unicellular and have two flagella which are of unequal lengths. Most of the dinoflagellates belong to this class and dinocysts are very useful in biostratigraphy. The flagella are microscopic hair-like structures which are involved in the locomotion of a cell. The flagella has a whip-like appearance which helps them to propel through a liquid.

Complete answer:
Option A Anterior: In organisms having flagella, they are mostly found in the anterior position or front portion of the cell. An example of such an organism is Euglena. But in dinophyceae, flagella is not found on the anterior position.
Hence option A is not correct.
Option B One transverse and other vertical: The Dinophyceae has two flagella of unequal lengths. Here, one of the flagella is transverse which is known as cingulum and the other one is vertical, known as sulcus. They beat in a perpendicular direction, which enables them to move.
Hence option B is the correct answer.
Option C Lateral: In some vibrio species, two flagella are present – the polar flagella and lateral flagella. When the polar flagella meets too much resistance to turn, the lateral flagella gets expressed. Lateral flagella mainly provides swarming motility on viscous fluids or on surfaces. Dinophyceae does not have lateral flagella.
Hence option C is not correct.
Option D Posterior: These kinds of flagella are found in the posterior position or back portion of the cell. Certain fungi species have posterior flagella. Since Dinophyceae does not have posterior flagella.
So, option D is wrong.

Hence,Option B: One transverse and other vertical is the correct answer.

Note:
Flagella mainly helps an organism in its movement. They also function as a sensory organ to detect temperature and pH changes around them. Flagellum is used to increase reproduction rates in a few eukaryotes. Some of the recent researches have shown that flagella is also being used as a secretory organelle. Flagella are mostly present in protozoans and choanocyte cells of Metazoa. It is also found in other classes such as in plants, in gamete cells, and in algae.