Quiz: Plant Tissue Culture — 27 questions

1. Where should the alcohol treatment, chemical sterilization, and sterile-water rinsing of explants be performed?

A. Inside a laminar-air-flow cabinet or pre-sterilized inoculation chamber

B. In a dark culture room without airflow control

C. Inside a greenhouse beside the culture containers

D. On an open laboratory bench after detergent washing

Answer: (A)

Explanation

Initial detergent washing may occur in the general laboratory, but subsequent alcohol, sterilant, and sterile-water steps require an aseptic laminar-air-flow area or pre-sterilized chamber.

2. A laboratory needs to prepare one litre of MS medium from stored nutrient stocks. Which procedure is appropriate?

A. Store the stocks at room temperature and use equal volumes of every stock

B. Add the stock solutions without dilution because they are already at working strength

C. Use only the 20X stock because 200X stocks are less concentrated

D. Mix the required amounts of 20X or 200X stocks stored at 4°C

Answer: (D)

Explanation

MS salts and vitamins are commonly stored as 20X or 200X stocks at 4°C and mixed in the required amounts to prepare one litre of medium. A 200X stock is more concentrated than a 20X stock.

3. Why are concentrated stock solutions used when preparing plant tissue culture media?

A. They make the final medium more concentrated than the stock solution

B. They reduce inaccurate weighing of small quantities during each preparation

C. They prevent all nutrients from dissolving before sterilization

D. They replace the need to adjust the final medium to working concentrations

Answer: (B)

Explanation

Stock solutions allow small quantities of constituents to be measured accurately and quickly. They are concentrated preparations that are diluted to working concentrations in the final medium.

4. Which historical achievement occurred in 1952?

A. Skoog and Miller demonstrated the effects of auxin and kinetin on organ formation

B. Morel and Martin produced the first virus-free plant through Dahlia shoot-tip culture

C. Murashige and Skoog developed the MS medium for tobacco tissue culture

D. Haberlandt introduced the concept of totipotency

Answer: (B)

Explanation

In 1952, Morel and Martin produced the first virus-free plant through shoot-tip culture of Dahlia. The other events occurred in different years.

5. Which agar content correctly distinguishes solid, semisolid, and liquid culture media?

A. Solid has 6–8% agar, semisolid has less agar, and liquid has none

B. Solid and semisolid media both have 6–8% agar, while liquid has none

C. Solid has no agar, semisolid has 6–8% agar, and liquid has less agar

D. Solid has less agar, semisolid has no agar, and liquid has 6–8% agar

Answer: (A)

Explanation

Solid media contain 6–8% agar, semisolid media contain a lower agar concentration, and liquid media contain no agar.

6. What does aseptic inoculation involve?

A. Immersing seeds in nutrient solution before exposing them to air

B. Transferring regenerated plants directly from culture vessels into the field

C. Growing untreated field material in soil under greenhouse conditions

D. Placing sterilized plant material onto culture medium under sterile conditions

Answer: (D)

Explanation

Aseptic inoculation is the placement of sterilized plant material on culture medium under sterile conditions to prevent microbial contamination.

7. Why must explants be rinsed thoroughly with autoclaved distilled water after chemical sterilization?

A. To increase the concentration of sterilant on the explant surface

B. To replace the sterilant with a stronger antimicrobial solution

C. To provide nutrients needed for immediate explant growth

D. To remove toxic sterilants that could damage plant tissues

Answer: (D)

Explanation

Sterilants are toxic chemicals, so thorough rinsing removes residual sterilant and helps prevent damage to plant tissues.

8. Which description best defines plant tissue culture?

A. Growing plant material on nutrient media under sterile conditions

B. Propagating whole plants outdoors through controlled pollination

C. Storing harvested plant organs under refrigerated conditions

D. Growing only plant seeds in soil enriched with nutrients

Answer: (A)

Explanation

Plant tissue culture involves culturing seeds, organs, explants, tissues, cells, or protoplasts on nutrient media under sterile conditions. It is not limited to whole organs.

9. Which statement best distinguishes plant tissue culture from micropropagation?

A. Plant tissue culture occurs in soil, whereas micropropagation occurs on artificial media

B. Plant tissue culture applies only to roots, whereas micropropagation applies only to shoots

C. Plant tissue culture uses sexual reproduction, whereas micropropagation uses only seed formation

D. Plant tissue culture includes many types of plant material, whereas micropropagation emphasizes large-scale clonal propagation

Answer: (D)

Explanation

Plant tissue culture is a broad term for culturing various plant materials under controlled aseptic conditions. Micropropagation specifically emphasizes large-scale clonal propagation.

10. How should prepared culture medium be contained during autoclave sterilization?

A. Seal it with tightly closed screw caps to prevent any gas exchange

B. Place it in open beakers so steam can contact the medium directly

C. Place it in flasks or tubes closed with non-adsorbent cotton plugs covered with paper or foil

D. Wrap the medium in dry paper without placing it in a flask or tube

Answer: (C)

Explanation

Prepared medium is placed in conical flasks or tubes and closed with non-adsorbent cotton plugs covered by paper or foil before autoclaving at 121°C and 15 lb/in² for 15–20 minutes.

11. Why can explants from aseptic seedlings generally be cultured without further surface sterilization?

A. The seeds were surface sterilized before germinating into aseptic seedlings

B. The seedlings develop naturally without any microbial exposure in all environments

C. The seed coats continue sterilizing every explant after removal

D. The culture medium chemically sterilizes explants after they are excised

Answer: (A)

Explanation

Seeds are surface sterilized and germinated on a basal nutrient medium, producing aseptic seedlings whose explants do not require another surface-sterilization step under this principle.

12. What did Haberlandt propose in 1902?

A. Using MS medium to culture tobacco tissues

B. Using high auxin levels to promote shoot formation

C. Producing the first virus-free Dahlia through shoot-tip culture

D. Culturing isolated plant cells in vitro on an artificial medium and the concept of totipotency

Answer: (D)

Explanation

In 1902, Haberlandt proposed culturing isolated plant cells in vitro on artificial media and introduced the concept of totipotency. MS medium was developed later, in 1962.

13. What temperature should generally be maintained for most plant tissue culture conditions?

A. Approximately 10 ± 2°C

B. Approximately 35 ± 2°C

C. Approximately 25 ± 2°C

D. Approximately 45 ± 2°C

Answer: (C)

Explanation

Most culture conditions require temperature control near 25 ± 2°C, providing a suitable range for tissue growth.

14. What is the primary purpose of surface sterilizing an explant before culture?

A. To increase the explant’s water absorption

B. To stimulate cell division inside the explant

C. To remove microorganisms from the explant surface

D. To eliminate microorganisms from internal tissues

Answer: (C)

Explanation

Surface sterilization is intended to remove microorganisms present on the explant surface. It is not described as a method for sterilizing internal tissues.

15. Why is plant tissue culture useful to commercial growers seeking many genetically matching plants?

A. It produces plants exclusively through natural seed dispersal

B. It replaces nutrient media with field soil during propagation

C. It increases genetic variation through repeated sexual reproduction

D. It enables asexual propagation and produces large quantities of clones

Answer: (D)

Explanation

Plant tissue culture is an asexual propagation method used to produce large quantities of clones of a particular plant. Clonal propagation generates genetically matching material rather than sexually produced variation.

16. Which combination correctly describes pH adjustment and hormone dissolution for MS medium?

A. Adjust pH to 5.8 with 0.1 N NaOH or HCl, dissolve auxins in absolute ethyl alcohol, and cytokinins in 1 N HCl

B. Adjust pH to 6.5 with 0.1 N NaOH only, dissolving both hormones in absolute ethyl alcohol

C. Adjust pH to 5.8 with concentrated sulfuric acid, dissolve both hormones in water

D. Adjust pH to 7.0 with distilled water, dissolve auxins in 1 N HCl, and cytokinins in absolute ethyl alcohol

Answer: (A)

Explanation

MS medium is adjusted to pH 5.8 using 0.1 N NaOH or 0.1 N HCl. Auxins are dissolved in absolute ethyl alcohol, whereas cytokinins are dissolved in 1 N HCl.

17. Which set of environmental factors must be controlled for successful plant tissue culture?

A. Root depth, fertilizer type, fruit color, canopy width, and pruning time

B. Seed size, soil texture, rainfall, wind speed, and field spacing

C. Temperature, illumination, photoperiod, humidity, and air circulation

D. Plant age, flower number, soil pH, pollinator activity, and harvest date

Answer: (C)

Explanation

Plant tissue cultures require control of temperature, illumination, photoperiod, humidity, and air circulation. These factors regulate the culture environment.

18. What does totipotency mean in plant tissue culture?

A. The capacity of separated plant material to regenerate into a complete plant

B. The formation of an undifferentiated cell mass that cannot regenerate

C. The ability of a culture medium to supply inorganic salts and vitamins

D. The production of roots by applying a high concentration of kinetin

Answer: (A)

Explanation

Totipotency is the capacity of separated plant organs, tissues, or cells to be manipulated in vitro and grown back into complete plants. Callus formation instead refers to an undifferentiated cell mass.

19. Which autoclave cycle is specified for sterilizing washed and wrapped glassware and equipment?

A. 15 lb/in² at 60°C for 3–4 hours

B. 15 lb/in² at 121°C for 15–20 minutes

C. 150°C in a dry oven for 15–20 minutes

D. 121°C in a dry oven for 3–4 hours

Answer: (B)

Explanation

After cleaning, rinsing, drying, and wrapping, glassware and equipment are autoclaved at 15 lb/in² and 121°C for 15–20 minutes. Autoclaving uses moist heat, unlike oven sterilization.

20. Why must the most suitable culture medium often be determined experimentally for a particular plant tissue?

A. Plant tissues grow equally well on all available media

B. The medium must contain agar before any tissue can grow

C. No single medium provides optimum growth for every plant tissue

D. Only chemically undefined media support plant tissue growth

Answer: (C)

Explanation

Different plant tissues have different nutritional and hormonal requirements, so the medium must be selected and modified through trial and error for the specific plant material.

21. What distinguishes a chemically defined culture medium from a chemically undefined medium?

A. The undefined medium contains measured concentrations of every constituent

B. Both media have identical compositions but different physical forms

C. The defined medium contains natural products with variable composition

D. Every constituent and its concentration are known in the defined medium

Answer: (D)

Explanation

A chemically defined medium has a known composition and concentration for every constituent. An undefined medium contains natural products whose exact composition and concentration are not known.

22. Which set contains the major components generally found in a plant culture medium?

A. Soil particles, pesticides, pollen, cellulose fibers, and field microorganisms

B. Inorganic salts, iron, vitamins, amino acids, growth substances, and carbohydrates

C. Water only, together with light, temperature, and atmospheric carbon dioxide

D. Proteins, lipids, starch granules, and intact plant organs

Answer: (B)

Explanation

A general culture medium contains inorganic salts, an iron source, vitamins, amino acids, growth substances, and a carbohydrate supply. These components support growth under in vitro conditions.

23. A culture experiment uses a high kinetin level and observes abundant shoot formation. Which principle does this result illustrate?

A. High kinetin promotes shoot formation, whereas high auxin promotes root formation

B. High kinetin promotes root formation, whereas high auxin promotes shoot formation

C. Neither kinetin nor auxin concentration influences organ formation

D. Both high kinetin and high auxin specifically promote callus formation

Answer: (A)

Explanation

Skoog and Miller showed in 1957 that a high kinetin level promotes shoot formation, while a high auxin level promotes root formation.

24. What is the main role of a greenhouse in plant tissue culture production?

A. To maintain regenerated plants permanently under fully controlled conditions

B. To provide the sterile chamber where explants receive chemical treatments

C. To replace the nutrient medium used for plant regeneration

D. To help regenerated plants transition from culture containers to field conditions

Answer: (D)

Explanation

Greenhouses provide an intermediate environment in which regenerated plants harden and develop root and leaf systems capable of tolerating field conditions.

25. What distinguishes macronutrients from micronutrients in a culture medium?

A. Macronutrients promote shoots, whereas micronutrients promote roots

B. Macronutrients are organic compounds, whereas micronutrients are living cells

C. Macronutrients are supplied as vitamins, whereas micronutrients are supplied as carbohydrates

D. Macronutrients are required in higher amounts, whereas micronutrients are required in smaller amounts

Answer: (D)

Explanation

Macronutrients are inorganic salts needed in higher amounts, while micronutrients are essential inorganic salts needed in smaller amounts.

26. What is a culture medium in plant tissue culture?

A. A controlled room that regulates temperature and light around cultures

B. A sterilization chamber used to remove microorganisms from explants

C. A soil mixture used to acclimatize plants after transplantation

D. An artificially prepared nutrient medium on which excised plant tissues and organs grow in vitro

Answer: (D)

Explanation

A culture medium is an artificially prepared nutrient medium that supports the in vitro growth of excised plant tissues and organs. Environmental control is provided by the culture room, not the medium.

27. Which pairing correctly identifies common plant growth regulators used in culture media?

A. Auxins include glycine and thiamine, while cytokinins include meso-inositol and pyridoxine

B. Auxins include IAA and NAA, while cytokinins include kinetin and BAP

C. Auxins include kinetin and zeatin, while cytokinins include IAA and IBA

D. Auxins include Fe-EDTA and calcium, while cytokinins include nitrogen and potassium

Answer: (B)

Explanation

Common auxins include IAA, 2,4-D, NAA, and IBA. Common cytokinins include kinetin, BAP, and zeatin.