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Unit 2: Preparation of plant tissue culture media - Practice Quiz

BTY559 — Biotechnology Laboratory-Ii 60 Questions
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1 Which gelling agent is most commonly used to solidify plant tissue culture media?

Preparation of semi-solid media Easy
A. Gelatin
B. Starch
C. Agar
D. Cellulose

2 The typical concentration of agar used to prepare semi-solid plant tissue culture media is about:

Preparation of semi-solid media Easy
A. to
B. to
C. to
D. to

3 What is the main difference between liquid and semi-solid plant tissue culture media?

Preparation of liquid media Easy
A. Liquid media has no nutrients
B. Liquid media contains double sugar
C. Liquid media lacks a gelling agent
D. Liquid media has no water

4 Liquid media cultures are often kept on a shaker mainly to:

Preparation of liquid media Easy
A. Increase the temperature
B. Add more nutrients
C. Provide aeration and prevent cell settling
D. Reduce contamination

5 Which of the following is the most commonly used carbon source in plant tissue culture media?

Media supplements Easy
A. Lactose
B. Sucrose
C. Fructose only
D. Glucose only

6 Plant growth regulators such as auxins and cytokinins are added to media to control:

Media supplements Easy
A. Agar strength
B. Growth and differentiation of tissues
C. Media color
D. Sterilization time

7 Which plant growth regulator primarily promotes root formation in tissue culture?

Media supplements Easy
A. Gibberellin
B. Cytokinin
C. Ethylene
D. Auxin

8 Which growth regulator mainly stimulates shoot formation and cell division?

Media supplements Easy
A. Auxin
B. Abscisic acid
C. Ethylene
D. Cytokinin

9 Which of the following is the most widely used basal medium in plant tissue culture?

Media supplements Easy
A. Luria-Bertani (LB) medium
B. Murashige and Skoog (MS) medium
C. Nutrient agar
D. Sabouraud medium

10 Vitamins such as thiamine and myo-inositol are added to media because they:

Media supplements Easy
A. Sterilize the medium
B. Act as gelling agents
C. Support metabolism and growth
D. Provide the carbon source

11 The pH of plant tissue culture media is usually adjusted to a range of approximately:

Media preparation - pH adjustment Easy
A. to
B. to
C. to
D. to

12 If the medium pH is too low, which problem is most likely to occur?

Media preparation - pH adjustment Easy
A. Vitamins increase
B. Agar may fail to solidify properly
C. The medium turns blue
D. Sucrose disappears

13 Which reagents are commonly used to adjust the pH of tissue culture media?

Media preparation - pH adjustment Easy
A. Ethanol and water
B. Sucrose and agar
C. HCl and NaOH
D. Agar and gelatin

14 Which equipment is most commonly used to sterilize plant tissue culture media?

Sterilization of media Easy
A. Refrigerator
B. Autoclave
C. Centrifuge
D. Hot plate

15 The standard autoclaving conditions for sterilizing culture media are:

Sterilization of media Easy
A. at psi for hours
B. at psi for minutes
C. at psi for – minutes
D. at psi for minutes

16 Heat-sensitive supplements that break down during autoclaving are best sterilized by:

Sterilization of media Easy
A. Boiling for 1 hour
B. Adding extra agar
C. Freezing overnight
D. Filter sterilization using membrane

17 Heat-labile components are usually added to the medium:

Sterilization of media Easy
A. After autoclaving, once it cools
B. During autoclaving
C. Only at boiling temperature
D. Before adjusting pH

18 Autoclaving achieves sterilization mainly through the action of:

Sterilization of media Easy
A. Chemical fumes
B. Dry cold air
C. Moist heat under pressure
D. Ultraviolet light

19 In semi-solid media preparation, agar is usually added and dissolved by:

Preparation of semi-solid media Easy
A. Heating the medium until agar melts
B. Adding it after autoclaving
C. Mixing it with cold water only
D. Cooling the medium in a fridge

20 A biological indicator commonly used to test the effectiveness of autoclave sterilization uses spores of:

Sterilization of media Easy
A. Escherichia coli
B. Geobacillus stearothermophilus
C. Saccharomyces cerevisiae
D. Lactobacillus casei

21 A researcher wants to prepare a semi-solid MS medium for callus induction. Which supplement is used as the gelling agent to achieve the semi-solid consistency?

Preparation of semi solid/liquid media with supplements Medium
A. Agar
B. Casein hydrolysate
C. Sucrose
D. Activated charcoal

22 Why is sucrose typically added to plant tissue culture media rather than relying on photosynthesis?

Preparation of semi solid/liquid media with supplements Medium
A. It raises the pH to the required level
B. Cultured tissues are largely heterotrophic and need an external carbon source
C. It sterilizes the medium during autoclaving
D. It acts as the primary gelling agent

23 To induce shoot formation from a callus, which balance of plant growth regulators should be used?

Preparation of semi solid/liquid media with supplements Medium
A. No growth regulators at all
B. High auxin to cytokinin ratio
C. High cytokinin to auxin ratio
D. Equal auxin and cytokinin only

24 What are the standard autoclave conditions for sterilizing plant tissue culture media?

Sterilization of plant tissue culture media Medium
A. at 15 psi for 15–20 minutes
B. at 30 psi for 5 minutes
C. at 10 psi for 60 minutes
D. at 5 psi for 30 minutes

25 The pH of plant tissue culture media is usually adjusted to which range before adding agar and autoclaving?

Preparation of semi solid/liquid media with supplements Medium
A. 4.0–4.5
B. 5.6–5.8
C. 8.0–8.5
D. 7.0–7.4

26 A medium contains a heat-labile growth regulator such as GA₃ (gibberellic acid). What is the best sterilization method for this component?

Sterilization of plant tissue culture media Medium
A. UV irradiation of the powder before weighing
B. Dry heat at for 2 hours
C. Autoclave it together with the rest of the medium
D. Filter sterilization through a membrane and add after autoclaving

27 Why is activated charcoal sometimes added to plant tissue culture media?

Preparation of semi solid/liquid media with supplements Medium
A. To act as the main carbon source
B. To adsorb inhibitory phenolic compounds released by explants
C. To increase the medium's pH
D. To serve as a gelling agent

28 A liquid medium (no gelling agent) is chosen for suspension culture. Which additional practice is essential compared to semi-solid culture?

Preparation of semi solid/liquid media with supplements Medium
A. Lowering pH below 4.0
B. Higher agar concentration
C. Continuous agitation or shaking for aeration
D. Complete removal of sucrose

29 In the MS medium, the major inorganic nitrogen sources are supplied mainly as which two forms?

Preparation of semi solid/liquid media with supplements Medium
A. Nitrate () and ammonium ()
B. Ammonia gas and glycine
C. Only nitrate ()
D. Nitrite and urea

30 After autoclaving, agar-containing medium should be dispensed into vessels at approximately what stage?

Sterilization of plant tissue culture media Medium
A. While still molten but cooled to about –
B. Only after it has fully solidified
C. Immediately at under pressure
D. After freezing and re-thawing

31 Which stock solution practice is commonly used to prepare media efficiently and accurately?

Preparation of semi solid/liquid media with supplements Medium
A. Autoclave all salts as dry powder before use
B. Prepare concentrated macro- and micronutrient stocks and dilute as needed
C. Weigh every salt individually for each batch
D. Add all salts directly without dissolving

32 To supply iron in a stable, available form, MS medium uses which chelated combination?

Preparation of semi solid/liquid media with supplements Medium
A. alone
B. combined with -EDTA
C. Iron oxide powder
D. Ferrous ammonium sulphate autoclaved with agar

33 Which of the following is NOT typically sterilized by autoclaving during media preparation?

Sterilization of plant tissue culture media Medium
A. Distilled water
B. Vitamin solutions and heat-sensitive antibiotics
C. Agar-containing basal medium
D. Glassware and pipettes

34 If agar concentration in a semi-solid medium is too high (e.g., above 1.0%), what problem is most likely?

Preparation of semi solid/liquid media with supplements Medium
A. Reduced nutrient diffusion and poor growth
B. Sharp drop in pH to below 3
C. Complete loss of gelling ability
D. Faster contamination by bacteria

35 Casein hydrolysate is sometimes added to media primarily to provide which class of supplement?

Preparation of semi solid/liquid media with supplements Medium
A. A gelling agent
B. A mixture of amino acids (organic nitrogen)
C. Inorganic phosphate
D. A carbon source only

36 A batch of autoclaved medium fails to solidify even after cooling. What is the most likely cause?

Sterilization of plant tissue culture media Medium
A. Sucrose concentration was too high
B. Too much agar was added
C. The medium was cooled too quickly
D. The pH was set too low, preventing proper agar gelling

37 Which growth regulator combination would best promote root induction from micro-shoots?

Preparation of semi solid/liquid media with supplements Medium
A. Only gibberellin, no auxin or cytokinin
B. Equal high levels of both auxin and cytokinin
C. High cytokinin (e.g., BAP) with no auxin
D. High auxin (e.g., IBA or NAA) with low or no cytokinin

38 Why must autoclave chamber air be properly displaced by steam before the sterilization timer starts?

Sterilization of plant tissue culture media Medium
A. Trapped air lowers the effective temperature and prevents proper sterilization
B. Air increases sucrose caramelization
C. Air makes the medium too acidic
D. Air causes agar to over-solidify

39 Myo-inositol and thiamine are commonly added to MS medium under which category of supplements?

Preparation of semi solid/liquid media with supplements Medium
A. Vitamins/organic supplements
B. Carbon sources
C. Gelling agents
D. Macronutrient salts

40 For sterilizing large volumes of medium in bottles, why should caps be kept loosely closed during autoclaving?

Sterilization of plant tissue culture media Medium
A. To allow steam penetration and prevent pressure build-up
B. To speed up agar solidification
C. To keep sucrose from crystallizing
D. To lower the medium's pH

41 A researcher prepares MS medium and adds agar, but after autoclaving the medium fails to solidify and remains liquid on cooling. Assuming the agar quantity is correct, which factor is the MOST likely cause?

Preparation of semi-solid media with agar Hard
A. The agar was added after pH adjustment
B. Sucrose concentration was set to
C. The medium pH was adjusted to before autoclaving
D. The medium pH was adjusted to before autoclaving

42 GA (gibberellic acid) and zeatin are heat-labile growth regulators required in a medium. What is the correct procedure to incorporate them without degradation?

Sterilization of heat-labile supplements Hard
A. Dissolve them in the medium and pasteurize at
B. Add them and autoclave at reduced pressure for 5 min
C. Add them to the medium before autoclaving at for 15 min
D. Filter-sterilize through a membrane and add to autoclaved medium cooled to

43 During autoclaving of tissue culture media, standard conditions are at for 15–20 min. If a larger volume vessel () is used instead of small flasks, what adjustment is MOST appropriate?

Autoclaving parameters and validation Hard
A. Increase the autoclave holding time to ensure the core reaches
B. Decrease the temperature to to protect nutrients
C. Increase pressure to while keeping time constant
D. Keep all parameters identical since sterilization depends only on pressure

44 A stock of a micronutrient is prepared. To make of final medium, what volume of this stock must be added?

Preparation of stock solutions Hard
A.
B.
C.
D.

45 In an MS medium, a high auxin-to-cytokinin ratio is applied to an explant. Which morphogenic response is MOST likely to be favored?

Auxin/cytokinin ratio and morphogenesis Hard
A. Shoot proliferation
B. Root initiation
C. Somatic embryo maturation exclusively
D. Callus with no differentiation only

46 The pH of plant tissue culture medium is typically adjusted to – before autoclaving. What commonly happens to the pH AFTER autoclaving?

pH adjustment and its effects Hard
A. It drops by approximately – units
B. It remains exactly unchanged
C. It becomes strongly alkaline ()
D. It rises by approximately unit

47 Sucrose is the preferred carbon source in plant tissue culture media. During autoclaving at acidic pH, sucrose partially hydrolyzes. What is the significance of this hydrolysis?

Carbon source selection Hard
A. It converts sucrose entirely into insoluble starch
B. It raises the osmotic potential to lethal levels
C. It completely destroys all available carbon
D. It yields glucose and fructose, which some cultures utilize more readily

48 A researcher replaces agar with Gelrite (gellan gum) at a lower concentration. What is the primary reason Gelrite is used at concentrations much lower than agar?

Gelling agent alternatives Hard
A. Gelrite is a protein that denatures to form a network
B. Gelrite gels effectively at due to strong cation-mediated gelation
C. Gelrite must be used at like agar for equivalent firmness
D. Gelrite requires no divalent cations and gels instantly at any temperature

49 Membrane filtration () is used to sterilize heat-labile additives. Which statement BEST explains why this pore size is chosen over ?

Filter sterilization mechanism Hard
A. filters allow faster flow rates than
B. removes viruses while does not
C. is only used for gases, never liquids
D. reliably retains most bacteria including small ones that pass

50 Increasing sucrose from to in a somatic embryogenesis protocol primarily influences the culture by:

Osmotic effects of media components Hard
A. Acting purely as a pH buffer with no osmotic role
B. Providing nitrogen for protein synthesis
C. Lowering the osmotic potential to zero
D. Raising osmotic stress that can promote embryo maturation

51 What is the correct sequence when preparing semi-solid MS medium?

Order of media preparation steps Hard
A. Add stocks and sucrose → make up volume → adjust pH → add agar → autoclave → dispense
B. Adjust pH → autoclave → add stocks and sucrose → dispense
C. Autoclave water → add all stocks and agar → adjust pH → dispense cold
D. Add agar → autoclave → adjust pH → add stocks → dispense

52 Activated charcoal (–) is sometimes added to media. A student finds that a growth regulator added at the usual concentration now gives no response. What is the MOST likely explanation?

Activated charcoal supplement Hard
A. Activated charcoal raises the pH above , denaturing the regulator
B. Activated charcoal adsorbs the growth regulator, reducing its effective concentration
C. Activated charcoal converts the regulator into agar
D. Activated charcoal chelates only micronutrients, not regulators

53 MS medium provides nitrogen as both nitrate () and ammonium (). If ammonium is supplied without any nitrate, a common consequence for many cultures is:

Nitrogen source balance in MS medium Hard
A. Culture toxicity and medium acidification as uptake releases H
B. Complete inhibition of sucrose uptake
C. No effect since only total nitrogen matters
D. Rapid alkalization to pH with enhanced growth

54 In MS medium iron is supplied as Fe-EDTA rather than as a simple ferric salt. What is the primary reason?

Iron source stability Hard
A. EDTA serves as the main carbon source for iron transport
B. EDTA chelation keeps iron soluble and available across the culture pH range
C. EDTA converts Fe to gaseous form for aeration
D. EDTA increases iron precipitation to control uptake

55 A cell suspension is grown in liquid MS medium on an orbital shaker. Compared to semi-solid culture, a key reason liquid media require agitation is:

Liquid media and aeration Hard
A. To physically break all cells into single protoplasts
B. To provide aeration and prevent cells from settling and becoming anoxic
C. To keep agar evenly suspended throughout the flask
D. To raise the medium temperature by friction

56 In many defined media, myo-inositol is added at , a much higher amount than typical vitamins (often ). This is because myo-inositol primarily functions as:

Vitamin supplementation Hard
A. The sole nitrogen source for the culture
B. A precursor for membrane phospholipids and cell wall components required in larger amounts
C. A gelling agent replacing agar
D. A trace catalytic cofactor needed in only nanogram quantities

57 A batch of autoclaved media shows fungal contamination only in flasks that were filled to near the top and tightly capped. The autoclave logged for 20 min. What is the MOST likely cause?

Contamination troubleshooting Hard
A. The pH was too low for sterilization to occur
B. Poor steam penetration into full, tightly sealed vessels prevented adequate sterilization
C. The agar concentration was too high to sterilize
D. Fungal spores are resistant to at all times

58 When preparing a combined macronutrient stock, calcium and phosphate/sulphate salts should NOT be mixed at very high concentration in the same stock because:

Concentrated stock preparation and precipitation Hard
A. The stock would gel like agar
B. Calcium destroys sucrose in the stock
C. Insoluble precipitates such as calcium phosphate/sulphate can form
D. They react to produce toxic gases

59 A medium contains a mixture where most components are heat-stable but one antibiotic used for Agrobacterium control is heat-labile. What is the correct combined strategy?

Autoclaving vs filtration decision Hard
A. Autoclave everything together since one heat-stable majority dominates
B. Autoclave the bulk medium, then filter-sterilize and add the antibiotic after cooling
C. Add the antibiotic before autoclaving and increase its dose to compensate
D. Filter-sterilize the entire medium including agar

60 The auxin IAA and cytokinins like BAP are often poorly soluble in water. What is the standard method to dissolve them before adding to media?

Growth regulator solubility Hard
A. Dissolve in a small volume of dilute NaOH or KOH (or ethanol/DMSO), then make up with water
B. Autoclave the solid regulator to melt it
C. Dissolve directly in cold water only
D. Dissolve in concentrated sucrose syrup
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