Question

this are very difficult questions for my environmental biology class. These are examples from the practice homework so can anyone please help me check my answers.

6) Which of the following are NOT found in a sterile medium, both liquid and solid? A) Living organisms B) Macronutrients C) Buffer D) Micronutrients the 7) You collect cells in the to study endospore formation/sporulation, and cells in to study mature dormant endospores. A) Lag phase; Log phase B) Log phase, Stationary phase C) Stationary phase, Death phase D) Death phase, Log phase 8) You are given an agar plate with many colonies and labeled Proteus mirabilis. How can you proceed to start a pure culture of P. mirabilis ? A) Transfer cells from a well-isolated colony. B) Use aseptic technique to prevent contamination. C) Transfer cells to a sterile broth. D) All of the above 9) Which of the following is NOT CORRECT about a well-isolated colony of P. mirabilis? A) Each colony is a population of identical cells. B) Each colony is a supercell that has completed the growth curve. C) Each colony is made up of P. mirabilis cells. D) Each colony originated from one P. mirabilis cell.

Answer 1

Sterile medium is sterilized by heating to a high temperature which prevents the growth of any living
organisms.
The medium contains buffer and other nutrients.
Option A is the answer

You collect cells in the STATIONARY PHASE to study endospore formation and the cells in the DEATH phase
to study mature dormant endospores.
Endospores are studied in the stationary phase as the secondary metabolites are produced in this phase.
Option C is the answer.

A pure colony is free from other microbes.
So to start a pure culture of P.mirabilis one can transfer cells pure colony and use aseptic technique and transfer
cells to a sterile broth.
Hence option D is the answer

A colony is a population of identical P.mirabilis cells that originated from a single cell.
Hence option B is the answer