Unit 2: Micropropagation; Somatic Hybridization - Practice Quiz

1 Micropropagation refers to the in vitro propagation of plants using which technique?

2 Which of the following is the correct first stage of micropropagation?

3 The small piece of plant tissue used to start a micropropagation culture is called a(n):

4 The final stage of micropropagation, where plantlets are gradually adapted to external environmental conditions, is known as:

5 Somatic embryogenesis is the process of forming embryos from:

6 Embryos produced through somatic embryogenesis are commonly referred to as:

7 A key feature that distinguishes a somatic embryo from a shoot bud is that a somatic embryo is:

8 Embryo culture involves the aseptic isolation and in vitro growth of:

9 One common purpose of embryo culture is to:

10 Embryo rescue is mainly used to save embryos that would otherwise:

11 Embryo rescue is especially valuable in producing which type of plants?

12 A major application of micropropagation is the rapid production of:

13 Micropropagation is useful for producing plants that are free of which of the following?

14 A protoplast is a plant cell that lacks its:

15 Which enzymes are commonly used to remove the plant cell wall during protoplast isolation?

16 Which chemical agent is widely used to induce protoplast fusion?

17 The method of fusing protoplasts using an electric field is called:

18 After protoplast fusion, why is selection of hybrid cells necessary?

19 Which of the following can be used as a visual marker for selecting fused hybrid cells?

20 A symmetric hybrid produced by somatic hybridization contains:

21 A tissue culture lab observes that shoots multiplied in vitro fail to survive when directly transplanted to the field. Which stage of micropropagation was most likely inadequate?

22 During the multiplication stage of micropropagation, a high cytokinin-to-auxin ratio in the medium primarily promotes which response?

23 Which explant is generally preferred for establishing virus-free plants through micropropagation?

24 Which feature distinguishes a somatic embryo from an adventitious shoot arising in culture?

25 In carrot suspension cultures, transferring embryogenic cells to a medium with reduced auxin (2,4-D) typically triggers which event?

26 Somatic embryos are the biological basis of which agricultural product?

27 A breeder cultures immature embryos on nutrient medium to overcome seed dormancy and shorten the breeding cycle. This technique is best described as:

28 Why do very young (immature) excised embryos often require a more complex medium than mature embryos?

29 In a wide (interspecific) cross, fertilization succeeds but the hybrid embryo aborts due to endosperm failure. Which technique can recover a viable hybrid?

30 Embryo rescue is most valuable in plant breeding because it primarily helps overcome which barrier?

31 Which of the following is the single most important advantage of micropropagation over conventional propagation for the commercial ornamental industry?

32 The unexpected appearance of genetic variation among micropropagated plants, often associated with a prolonged callus phase, is called:

33 Which application relies on micropropagation to preserve endangered or elite germplasm for long periods?

34 Which enzyme combination is typically used to remove the plant cell wall and release protoplasts?

35 To prevent osmotic bursting of freshly isolated protoplasts, the medium must be:

36 Which agent is most commonly used as a chemical fusogen to induce protoplast fusion?

37 Two parental protoplasts, one resistant to antibiotic A and the other resistant to antibiotic B, are fused. Growing the mixture on medium containing both antibiotics selects for which cells?

38 Which method allows physical selection of fusion products based on differences such as colour of chloroplasts versus colourless (albino) protoplasts?

39 An asymmetric somatic hybrid differs from a symmetric hybrid mainly because:

40 To create an asymmetric hybrid, the donor protoplast's nuclear genome is usually fragmented before fusion by treating it with:

41 During Stage II (multiplication) of micropropagation, a culture that initially showed vigorous shoot proliferation begins producing shoots with translucent, water-soaked, thick appearance and poor rooting. The most likely biochemical basis for this disorder is:

42 A protocol yields a multiplication rate of 4 shoots per explant every 4-week subculture. Starting with 5 explants, approximately how many shoots are theoretically available after 20 weeks (5 subcultures), assuming no losses?

43 In carrot somatic embryogenesis, cells maintained in high 2,4-D form proembryogenic masses but fail to progress to globular embryos. The essential manipulation to trigger embryo development is:

44 Which feature most reliably distinguishes a true somatic embryo from an adventitious shoot arising via organogenesis?

45 Immature embryos cultured in vitro often require a more complex medium than mature embryos. The primary physiological reason is:

46 The phenomenon where an excised immature embryo germinates directly into a seedling without passing through normal maturation and dormancy is termed:

47 In a wide cross between two species, fertilization succeeds but the hybrid embryo aborts by day 12 due to endosperm breakdown. The optimal embryo rescue strategy is:

48 Ovule culture and ovary culture are chosen over direct embryo excision in some interspecific crosses primarily because:

49 Meristem-tip culture is preferred for producing virus-free plants because:

50 A commercial lab notices increasing phenotypic variation in a clonally micropropagated ornamental after many subcultures. To minimize this problem while maintaining clonal fidelity, the best practice is:

51 During enzymatic protoplast isolation, cellulase and macerozyme (pectinase) are used together. Their complementary roles are:

52 In PEG-mediated versus electrofusion of protoplasts, a key advantage of electrofusion is:

53 When two different protoplast populations are mixed and fused randomly, the fusion products include several types. The desired heterokaryon is:

54 In complementation-based selection, two parental lines each carry a non-allelic recessive mutation blocking growth on selective medium. Only fusion hybrids grow because:

55 A researcher fuses protoplasts where one parent is chlorophyll-deficient (albino, cannot photosynthesize) and the other is sensitive to a metabolic inhibitor. Hybrids are selected on inhibitor-containing medium under light. This dual/complementation scheme works because:

56 To transfer only a small segment of the donor genome (e.g., a disease-resistance gene) into a recipient while retaining the recipient's genome intact, one produces an asymmetric hybrid by:

57 A symmetric somatic hybrid between two distantly related species is often unstable and shows chromosome elimination. The main reason symmetric hybridization is limited for wide crosses is:

58 A cybrid is best defined as a cell/plant containing:

59 To generate a cybrid transferring cytoplasmic male sterility (CMS) into an elite line, the standard donor–recipient protocol involves:

60 Fluorescence-activated cell sorting (FACS) can isolate heterokaryons when the two parental protoplasts are pre-labelled with different fluorochromes. The principle enabling selection is: