Question

Is the culture medium: Phenyl ethyl Alcohol ( PEA)

1. Selective
2. Differential

Bacteria	Gram stain	Growth	Changes in the culture medium or bacteria
Escherichia coli	Negative	no
Pseudomonas fluorescens	negative	no
Enterobacter aerogenes	negative	no
Alcaligenes faecalis	Negative	no
Micrococcus luteus	Negative	yes	No changes
Staphylococcus epidermidis	positive	yes	No changes
Enterococcus faecalis	positive	Yes	No changes
Bacillus cereus	positive	Yes	No changes

1. Only 1
2. Only 2
3. Both 1 and 2
4. Neither 1 or 2

Syprogyra is ________.

1. A eukaryotic organism
2. Multicellular

1. Only 1
2. Only 2
3. Both 1 or 2
4. Neither 1 or 2

How Does escheria coli grow in a nutrient broth?

1. Turbid: finely dispersed growth throughout the broth
2. Sediment: granular substance at the bottom of the broth

1. Only 1
2. Only 2
3. Both 1 and 2
4. Neither 1 or 2

Answer 1

1 . Only 1 -Selective medium

The chart given shows that only the Gram positive organism grow in the given culture medium while inhibiting the gram negative bacteria. Hence it is a selective media for Gram positive bacteria. A selective media is the one which contain ingrediants that selectively inhibit a particular group of bacteria, while enabling other groups to grow. Hence in this media Phenyl Ethyl alcohol selectively inhbits gram negative bacteria by interfering with its DNA synthesis, while enabling gram positive bacteria to grow

2.c. Both 1 and 2

Spirogyra is filamentous green algae that is named so due to the presence of spiral shaped chloroplast distributed in the cytoplasm. It is a multicellular eukaryotic organism. The plant body called thallus is an unbranched muticellular filamentous structure formed by the arrangement of cylindrical cells head to head in a single row

3.1.Only 1 Turbid:finely dispersed growth throughout the broth

The growth of E coli generally occurs as uniform turbidity in broth cultures following incubation for 12-18 hours. Some forms also forms heavy deposits that disperses on shaking