Unit 8: Protoplast fusion - Practice Quiz

1 What does the abbreviation PEG stand for in protoplast fusion?

2 A protoplast is a plant cell that lacks which structure?

3 PEG acts as which type of agent in protoplast fusion?

4 The fusion of two protoplasts from different species produces a cell called a:

5 Which enzyme is commonly used to remove the cell wall and isolate protoplasts?

6 Protoplast fusion is an example of which type of hybridization?

7 In the PEG method, PEG promotes fusion mainly by inducing:

8 The main advantage of protoplast fusion over conventional breeding is that it overcomes:

9 A hybrid cell containing the nucleus of one parent and the cytoplasm mixed from both is called a:

10 Which of the following is a chemical method of protoplast fusion?

11 During PEG treatment, protoplasts are usually kept in a medium that is:

12 After fusion, protoplasts regenerate a new cell wall and then divide to form a:

13 Which solution is often added after PEG treatment to help wash away PEG and improve fusion?

14 Fusion of two protoplasts from the same species is called:

15 The first step in a protoplast fusion experiment is:

16 PEG used for protoplast fusion typically has a molecular weight in the range of:

17 Which of the following enzymes helps degrade the middle lamella between plant cells during protoplast isolation?

18 A somatic hybrid produced by protoplast fusion contains genetic material from:

19 One disadvantage of the PEG fusion method is that PEG can be:

20 Protoplast fusion technology is mainly applied to produce improved:

21 In PEG-mediated protoplast fusion, what is the primary role of polyethylene glycol (PEG)?

22 Why is a high pH (--) high- solution often used together with PEG during fusion?

23 A product formed by the fusion of two protoplasts from different species, containing nuclei of both parents, is called a:

24 A cybrid produced through protoplast fusion is characterized by:

25 Before PEG-mediated fusion, protoplasts must first be isolated. Which treatment achieves this?

26 Which concentration range of PEG is typically effective for inducing protoplast fusion?

27 One major advantage of the PEG method over electrofusion for protoplast fusion is that it:

28 During PEG fusion, protoplasts must be maintained in an osmotically balanced medium mainly to prevent:

29 A researcher fuses protoplasts of two plants where one is resistant to a herbicide and the other to an antibiotic. Fused hybrids are selected on medium containing both agents. This selection strategy relies on:

30 The sequence of events in PEG-mediated fusion is best represented as:

31 Why is protoplast fusion particularly useful for producing hybrids between sexually incompatible plant species?

32 In PEG fusion, dimethyl sulfoxide (DMSO) is sometimes added to the PEG solution to:

33 A product of fusion between two protoplasts of the SAME species/parent is termed a:

34 Prolonged exposure to high concentrations of PEG during fusion mainly causes:

35 The intermediate cell containing two or more distinct nuclei immediately after membrane fusion but before nuclear fusion is a:

36 In a somatic hybridization experiment, if PEG treatment gives many fusion products but very few true hybrids survive on selection medium, the most likely explanation is:

37 Which of the following is a limitation of the PEG method of protoplast fusion?

38 After successful fusion and washing, the fusion products are cultured on nutrient medium primarily to allow:

39 Somatic hybridization by PEG fusion is especially valuable for transferring which trait, often controlled by cytoplasmic genes?

40 The main reason a high-, high-pH wash follows PEG addition rather than being applied first is that:

41 During PEG-mediated protoplast fusion, PEG promotes agglutination and membrane contact primarily because it acts as a molecular dehydrating agent. What is the direct physicochemical consequence of this dehydration at the membrane interface that permits fusion?

42 A researcher fuses protoplasts of species A () and species B (). Assuming a symmetric somatic hybrid retains both complete genomes without chromosome loss, what would be the chromosome number of the hybrid cell?

43 Adding a high concentration of at an alkaline pH (around pH 9–10) to the PEG fusion protocol enhances fusion frequency. Which mechanism best explains this synergistic effect?

44 In a PEG fusion experiment, when two protoplasts fuse but their nuclei do NOT fuse and remain separate within a common cytoplasm, the resulting product is called a:

45 Why is PEG of molecular weight around 1500–6000 Da typically preferred over very low molecular weight PEG (e.g., 200 Da) for protoplast fusion?

46 The stepwise dilution (gradual elution) of PEG with a fusion medium is a critical step. What is the primary rationale for diluting PEG slowly rather than washing it off abruptly?

47 A major limitation of PEG-mediated fusion compared to electrofusion is its non-selectivity and low reproducibility. Which downstream requirement does this limitation make absolutely essential for recovering true hybrids?

48 In somatic hybridization, if a protoplast fusion produces a cell containing the nucleus of one parent but organelles (chloroplasts/mitochondria) from both parents, the product is termed a:

49 Which combination of factors, if all present, would MOST likely reduce viable hybrid recovery in a PEG fusion protocol?

50 The classic Carlson somatic hybrid of two Nicotiana species was recovered by exploiting hormone-autotrophy of the hybrid. What principle of hybrid selection does this exemplify?

51 Suppose in a fusion mixture, the probability that any given protoplast is from species A is and from species B is , and pairwise fusions occur randomly. What fraction of all two-protoplast fusion events would be true A–B heterofusions?

52 Why must protoplasts be maintained in an osmotically balanced (isotonic/slightly hypertonic) medium throughout the PEG fusion procedure?

53 When distantly related (sexually incompatible) species are fused by PEG, hybrid cells frequently undergo progressive elimination of chromosomes of one parent during subsequent divisions. What is the most direct consequence for the resulting regenerated plant?

54 A common strategy uses irradiated 'donor' protoplasts and iodoacetate-treated 'recipient' protoplasts in PEG fusion (donor–recipient method). What is the combined logic of these two treatments?

55 If the PEG solution used for fusion is prepared without any divalent cations and at neutral pH, and no cations are supplied during elution, the expected outcome is:

56 Which statement correctly contrasts a key advantage of PEG fusion despite its drawbacks of toxicity and randomness?

57 A student obtains only of colonies as verified hybrids after PEG fusion despite good agglutination. Which analytical conclusion is most justified?

58 In the fusion product, mitochondrial and chloroplast genomes from both parents initially coexist but often segregate or recombine over cell generations. This phenomenon is significant because it can generate:

59 Consider a fusion protocol where exposure time to PEG is systematically varied: 5 min, 15 min, and 45 min. Fusion frequency rises then falls, peaking near 15 min. Which interpretation best explains this dose–response curve?

60 To confirm that a regenerated plant is a genuine somatic hybrid rather than a parental escape, which combination of evidence is MOST rigorous?