D.

nitrogen-fixation

Heterocysts are specialized nitrogen fixing cells during nitrogen starvation by some filamentous cyanobacteria. Certain cyanobacterias like Nostoc, Anabaena, Scytonenca, etc possess special cells, heterocysts to perform special functions like nitrogen-fixation.

B.

Sunflower - Free central placentation

Placentation is the arrangement of a placenta or placentae in the ovary of a flower. In sunflower, basal placentation is seen. The ovary is unilocular and bears a single placenta at a base with generally a single ovule. Other examples include Marigold and Ranunculus.

D.

Volvox is a fresh water, green, colonial algae containing fixed number of cells called coenobium. The cells are biflagellate and interconnected by cytoplasmic strands.

B.

Dinoflagellates

Bioluminescence is the property of a living organism to emit light. Some marine dinoflagellates show bioluminescence i.e., emitting light, Noctiluca, Pyrodinium, Pyrocystis, etc.

C.

A - 4; B - 3; C - 2; D - 1

The number and distribution of flagella on the bacterial surface are characteristics for a given species, based on this flagella can be

A. Monotrichous - A single flagella that extends from one end of the cell.

B. Amphitrichous - A single or multiple flagella that extends from both ends of the cell.

C. Lophotrichous - Multiple or several flagella that extends from one or both ends of the cell.

D. Peritrichous - Multiple flagella may be randomly distributed over the entire bacterial cell.