Unit 6: Recent Advancements in Plant Biotechnology; Molecular Markers - Practice Quiz

1 What does the abbreviation TCL stand for in plant biotechnology?

2 A transverse thin cell layer (tTCL) explant is cut in which orientation relative to the plant axis?

3 What is the main advantage of using thin cell layer technology in micropropagation?

4 Which nanoparticles are most commonly used as antimicrobial/sterilizing agents in plant tissue culture?

5 Nanoparticles added to culture media can act as a source of which type of nutrient?

6 One key property of nanoparticles that makes them effective in tissue culture is their:

7 Meta-topolin belongs to which class of plant growth regulators?

8 Meta-topolin is often preferred over BAP (6-benzylaminopurine) because it:

9 Melatonin in plants primarily functions as a:

10 Melatonin is known to help plants tolerate which of the following?

11 What does RFLP stand for?

12 RFLP analysis relies mainly on the use of which enzymes to cut DNA?

13 RAPD markers are generated using PCR with which type of primers?

14 A major limitation of RAPD markers is that they are:

15 SSR markers are also commonly known as:

16 What does the abbreviation ISSR stand for?

17 AFLP technique combines which two key steps?

18 SCAR markers are usually developed from which type of markers?

19 Molecular markers are widely used in tissue culture to detect:

20 In plant breeding, molecular markers are commonly used for:

21 A researcher excises a longitudinal strip from a tobacco stem containing only the epidermal and a few sub-epidermal cell layers. This preparation is most accurately described as which type of explant?

22 Why does thin cell layer (TCL) technology generally give higher morphogenic efficiency than conventional large explants?

23 In a TCL system, the developmental pathway (root, shoot, flower or callus) that the explant follows is primarily controlled by which factor?

24 Silver nanoparticles (AgNPs) are increasingly used as surface sterilants in plant tissue culture instead of mercuric chloride mainly because they:

25 The antimicrobial activity of silver nanoparticles is best attributed to which mechanism?

26 When added at low concentrations as media components, nanoparticles such as ZnO or TiO can enhance in vitro growth mainly by:

27 Meta-topolin is often preferred over the classical cytokinin BAP (6-benzylaminopurine) in micropropagation because it:

28 Chemically, meta-topolin belongs to which class of cytokinins?

29 Melatonin (N-acetyl-5-methoxytryptamine) added to culture media is valued mainly for which combined roles?

30 Melatonin is biosynthetically derived from which amino acid, sharing part of its pathway with auxin?

31 In an RFLP analysis, a point mutation abolishes a restriction site in one allele. What band pattern change is expected relative to the wild-type allele on a Southern blot?

32 Which feature makes RFLP markers co-dominant, allowing heterozygotes to be distinguished from homozygotes?

33 A key limitation of RAPD markers compared with most other PCR-based markers is that they are:

34 RAPD analysis differs fundamentally from targeted PCR because it uses:

35 Simple sequence repeats (SSRs) are highly informative markers largely because their polymorphism arises from:

36 How does ISSR primer design differ from SSR (microsatellite) primer design?

37 Arrange the core steps of AFLP in the correct order:

38 Why does AFLP achieve high multiplex ratios (many markers per reaction) with good reproducibility?

39 A SCAR marker is typically developed by:

40 Compared with the RAPD marker it is derived from, a SCAR marker generally shows:

41 A researcher isolates a transverse thin cell layer (tTCL) versus a longitudinal thin cell layer (lTCL) from the same tobacco floral stem. Which statement best explains why tTCL and lTCL frequently yield different morphogenic outcomes despite originating from the same explant?

42 Why does TCL technology often achieve higher regeneration frequencies and greater control over morphogenesis compared to conventional explants?

43 In tissue culture, silver nanoparticles (AgNPs) are used both as sterilants and as media additives. What is the primary mechanistic reason AgNPs can simultaneously reduce microbial contamination and, at low doses, enhance shoot proliferation?

44 A researcher observes that increasing AgNP concentration in the medium initially boosts callus growth but sharply inhibits it beyond a threshold. Which explanation best accounts for this biphasic (hormetic) response?

45 Meta-topolin (mT) is increasingly preferred over BAP (6-benzylaminopurine) for micropropagation of several species. Which combination of properties best explains mT's advantage in reducing physiological disorders during repeated subculture?

46 Melatonin (N-acetyl-5-methoxytryptamine) is used in plant tissue culture beyond a growth-regulatory role. Which dual functional property makes it particularly valuable for micropropagation under stress conditions?

47 A plant geneticist scores an RFLP locus and finds that a homozygote shows a single band while the heterozygote shows three bands. What is the most likely molecular explanation for the extra band in the heterozygote?

48 Compared with PCR-based markers, why is classical RFLP considered highly reproducible across laboratories yet impractical for high-throughput screening?

49 RAPD markers are dominant and often criticized for poor reproducibility. Which single change in reaction conditions is MOST likely to alter the RAPD banding pattern and why?

50 Two individuals share a RAPD band of identical size. Why is it risky to assume this shared band represents the same allele or locus (homology)?

51 SSR (microsatellite) markers are prized as codominant and highly polymorphic. What molecular mechanism primarily generates the length polymorphism (variable repeat number) at SSR loci?

52 ISSR and SSR markers both target microsatellites, yet ISSR does not require prior sequence knowledge whereas SSR does. Which statement correctly contrasts their primer design and dominance behavior?

53 In AFLP, selective amplification uses primers with selective nucleotides at their 3' ends. What is the functional purpose of adding these selective bases?

54 AFLP typically uses a rare cutter (e.g., ) combined with a frequent cutter (e.g., ). Why is this two-enzyme combination advantageous over using two rare cutters or two frequent cutters?

55 A RAPD band linked to a disease-resistance trait is converted into a SCAR marker. What is the principal benefit gained by this conversion?

56 A SCAR marker developed from a RAPD band amplifies a product in both resistant and susceptible plants of equal size, unlike the original RAPD which was present only in resistant plants. Which explanation best resolves this apparent loss of polymorphism?

57 To confirm the genetic fidelity (trueness-to-type) of micropropagated clones and detect somaclonal variation, which marker strategy provides the most robust genome-wide assessment, and why?

58 In marker-assisted selection (MAS) for introgressing a resistance gene, why are flanking codominant markers on both sides of the target gene preferred over a single dominant marker within the gene region?

59 A breeder wants to detect off-type contaminants and verify hybrid purity in a commercial seed lot. Which property of SSR markers makes them especially suited for this quality-control task?

60 When constructing a saturated linkage map for QTL analysis, why might a researcher favor AFLP markers in the early stage despite their dominant nature?