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Principles of Plant Genetics and Breeding

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198 CHAPTER 11<br />

Part A<br />

Please answer the following questions true or false:<br />

Outcomes assessment<br />

1 MS medium was developed by Morris <strong>and</strong> Stevenson.<br />

2 Agar is used as a gelling agent in tissue culture.<br />

3 A protoplast is all the cellular component <strong>of</strong> a cell plus the cell wall.<br />

4 An auxin : cytokinin ratio in favor <strong>of</strong> auxin promotes rooting.<br />

5 Propagation by cuttings is a form <strong>of</strong> clonal propagation.<br />

6 Diplospory is the most common mechanism <strong>of</strong> apomixis in higher plants.<br />

7 Facultative apomicts reproduce exclusively by apomixis.<br />

8 Pathogenesis is equivalent to haploidy.<br />

Part B<br />

Please answer the following questions:<br />

1 The part <strong>of</strong> the plant used to start tissue culture is called the ……………………..<br />

2 The MS tissue culture medium is named after ……………… <strong>and</strong> ……………….<br />

3 A mass <strong>of</strong> undifferentiated cells such as meristematic cells is called …………….........<br />

4 What is clonal propagation?<br />

5 What is apomixis?<br />

6 Distinguish between apospory <strong>and</strong> displospory as mechanisms <strong>of</strong> apomixis.<br />

7 Species that reproduce exclusively (or nearly so) by apomixis are described as …………………………..<br />

8 Give a specific advantage <strong>of</strong> clonal propagation.<br />

Part C<br />

Please write a brief essay on each <strong>of</strong> the following topics:<br />

1 Why is it possible (at least theoretically) to raise a full plant, or for that matter any organism, from just one <strong>of</strong> its own cells?<br />

2 All cells are not totipotent. Explain.<br />

3 What is the importance <strong>of</strong> a callus phase in plant tissue culture research?<br />

4 Discuss the rationale for the composition <strong>of</strong> a tissue culture medium.<br />

5 Describe the in vitro production <strong>of</strong> hybrids.<br />

6 Discuss practical applications <strong>of</strong> tissue culture in plant breeding.<br />

7 Discuss the key breeding implications <strong>of</strong> clonal propagation.<br />

8 Discuss the benefits <strong>of</strong> apomictic cultivars in crop production.<br />

9 Apomixis can be a two-edged sword in plant breeding. Explain.<br />

10 Discuss the occurrence <strong>of</strong> apomixis in nature.

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