For several decades now, amphibian species worldwide have been in decline. A significant proportion of the decline seems to be due to the spread of the chytrid fungus, Batrachochytrium dendrobatidis (Bd). Chytrid sporangia reside within the epidermal cells of infected animals, animals that consequently show areas of sloughed skin. They can also be lethargic, which is expressed through failure to hide and failure to flee. The infection cycle typically takes four to five days, at the end of which zoospores are released from sporangia into the environment. In some amphibian species, mortality rates approach 100%; other species seem able to survive the infection.

Sexual reproduction has not been observed in Bd. A Bd sporangium initially contains a single, haploid cell. Which of the following processes must be involved in generating the multiple zoospores eventually produced by each sporangium?

1. S phase
2. cytokinesis
3. mitosis
4. meiosis

1 and 2
1 and 3
2 and 3
1, 2, and 3
1, 2, and 4

During the interphase, the cell will pass through the G1 phase where it will undergo growth and development. It will then proceed to S phase where it will synthesize DNA before proceeding to G2 phase where protein is synthesized.

From the G2 phase, the cell proceeds to m phase which represents mitotic division phase where it divides and produce two daughter cells for each cycle. The stages in the division involves prophase, metaphase, anaphase, telophase and finally, cytokinesis.

Cytokinesis represents the last stage during which the cytoplasm divides to and the mother cell eventually gives rise to 2 independent daughter cells.

Hence, S phase, cytokinesis and mitosis are all involved in generating the multiple zoospores eventually produced by each sporangium.