Question

1a. Describe the growth of individual and populations of unicellular organisms

1b. What causes the lag phase in a population growth curve and what is one factor that causes it?

1c. Compare the population growth of bacteria and protists

Answer 1

1a: Growth of individuals depends on the surrounding media in which they are grown. The individual cell grows in size by increasing their cytoplasmic contents, mitochondria, and after then duplication of each organelle for the division process. Population growth depends on the oxygen content (for aerobic), minerals, and nutrients in the growth media. First, they adapt in the new culture for a time known as "lag-phase". During the phase, they adapt to a new environment include antibiotics (If specific species are allowed to grown). After then the exponential phase in which they grow very fastly till all the nutrients get consumed by all cells. The stationary phase is the highest number of living cells in the media and then in the last death stage where all cells compete for the nutrients.

1b: Lag phase is generally termed for the adaptation phase in which new cells start dividing and all components of the new cells depend upon the initial volume of cells and the types of cells inoculated in the media. Factors influencing includes the type of cells, inoculum size, and the precise environment for the growth of the new cells.

1c: Bacteria shows a limited pattern of growth while protists show an inclining growth in the growth curve. As you know protists are eukaryotic cells thus they generally do not secretes substances that inhibit the growth of other protists but bacteria do.