MCB Practical

Question 1

USING of MICROSCOPE

Answer 1

1. Clean with towel and alcohol yung microscope
2. Clean the lenses with separate lens papers
3. When using OIO, clean slide using paper towel afterwards
4. When using OIO, clean the objective lens with lens paper first then lens paper with ethyl alcohol
5. Clean microscope with towel and alcohol

Question 2

After hanging drop and wet mount observation, how to clean slide?

Answer 2

Place in 70% alcohol

Question 3

Name the specimens under each sample preparation

Answer 3

HD
1. Carmine dye
2. Protozoan Culture (hay infusion)
3. Bacterial Culture (Proteus sp., Bacillus sp., Staphylococcus sp., & Micrococcus luteus)

WM
1. Mold Culture (Aspergillus niger & Rhizopus sp.)
2. Yeast Culture (Saccharomyces cerevisae & Schizosaccharomcyes sp.)
3. Algal Culture (Chlorella)

Question 4

In wet mount, how should you prepare the following cultures:

broth
surface growth
mold

Answer 4

broth - place directly on slide

surface growth - put water first then mix specimen

mold - put lactophenol first, put specimen, than tease with a second needle

Question 5

4 basic steps for preparing a sample for staining

Answer 5

1. Place sample
2. Air dry
3. Heat film side up OR fix by 95% alcohol for 1 min then drain
4. Staining Procedure (use clothes pin as they are carcinogenic)

Question 6

SIMPLE STAINING (3 steps)

Answer 6

3-5 mins methylene blue
Wash with water
Blot dry

Question 7

NEGATIVE STAINING (4)

Answer 7

Put Negative Stain
Spread another slide across
Drain of excess dye
Air/Blot Dry

Question 8

DIFFERENTIAL STAINING (5)

Answer 8

Stain with methylene blue (5 seconds)
Wash with water (don’t dry)
Stain with carbol fuschin (3 seconds)
Wash with water
Blot dry

Question 9

GRAM STAINING (9)

Answer 9

Crystal Violet (1 min)
Wash with water (don’t dry)
Iodine (1 min)
Wash with water (don’t dry)
Alcohol (15-20 secs)
Wash with water (don’t dry)
Safranin (30 secs)
Wash with water
Blot dry

Question 10

Purpose of each gram stain

Answer 10

Crystal Violet - Primary Stain
Iodine - Mordant
Alcohol - Decolorizer
Safranin - Counterstain

Question 11

Types of pH indicators

Answer 11

Bromcresol green
yellow - 3.8
green - 4
blue - 5.4

Bromthymol blue
yellow - 6
green - 7
blue - 7.6

Phenolphthalein
colorless - 8 or less
pink - 9
red - 10

Question 12

Percentage for NUTRIENT AGAR PREPARATION

Answer 12

Peptone - 0.5%
Beef Extract - 0.3%
Agar: 1.5 - 2.0%

Question 13

Volume for petri dish

Answer 13

15-20 mL

Question 14

Volume for BIG TEST TUBE (18 mm)

• slants
• stab/broths

Answer 14

• 6 - 8 mL
• 10 mL

Question 15

Volume for SMALL TEST TUBES (13 mm)

• slant
• stab/broth

Answer 15

• 3 mL
• 5 mL

Question 16

What substance to put in
1. Erlenmeyer flask
2. Beaker

Answer 16

1. Agar
2. Remaining substances

Question 17

how to make cotton plug

Question 18

How to sterilize glass rod

Answer 18

95% alcohol

Question 19

How to titrate

Answer 19

Measure pH of initial coconut water
Add 0.5 mL indicator/10 mL CW
Titrate until desired
Titrate remaining CW w higher N titrant

Question 20

How much mL to put into POUR PLATE and SPREAD PLATE

Answer 20

PP: 1 mL
SP: 1

Question 21

In serial dilution, how much mL is transferred from 1 tube to another? for:

9 mL
9.9 mL

Answer 21

1 mL for 9 mL tubes

0.1 mL for 9.9 mL tubes