Questions 19S 



46. Give a botanical description of the part, in each of the following 

 plants, which is commonly used as food: —the Potato, the Onion, the 

 Turnip, and the Carrot. (1887.) 



47. What are the essential differences between a node and an inter- 

 node ? Illustrate your answer by examples. (1884.) 



48. Describe a bud. To what structures do the outer coverings corre- 

 spond ? What is the origin and use of the resinous secretion with which 

 they are often covered ? (1877 and 1 88 1.) 



49. Why are some of our fruit-trees thorny in the wild state, but not 

 when cultivated ? (1879.) 



50. Mention, with examples, the different members of the plant which 

 may be modified into tendrils. 



51. Explain precisely how a tendril acts. (l88l.) 



52. Explain the process of grafting. (1876.) 



53. What is the structural difference between a prickle (as in the Rose, 

 and a spine (as in the Blackthorn). (1881.) 



54. What is a leaf? What is its use to the plant ? (1877.) 



55. Describe the general structure of a leaf. 



56. What are stomata? Where are they found in the plant and 

 what is their use ? (1880.) 



57. What is the general plan of arrangement of leaves on a stem ? 

 Why is it the most advantageous to the plant ? (1 88 1.) 



58. What components of the atmosphere are taken from it by plants, 

 and for what purpose ? (1881.) 



59. What is the cause of the green colour of plants ? What is its use ? 



(I87S-) 



60. State why absence of light is injurious to plants. (1881.) 



61. Plants are said to 'starve in the absence of light.' Explain this 

 statement. (1883.) 



62. Why will a plant grown in a dwelling-room be less vigorous than 

 one grown in the open air ? (1879.) 



63. What is meant by respiration ? Describe an experiment for show- 

 ing that plants respire. (1878.) 



64. What is meant by transpiration ? Under what circumstances do 

 plants transpire most ? ( 1 879. ) 



65. What are the conditions, external and structural, which regulate 

 the amount of evaporation from leaves ? 



66. Explain the action of the leaves of carnivorous plants. 



67. Give instances in which leaves are only imperfectly developed. 

 What useful purposes may they serve in such cases? (1882.) 



68. Excluding the leaves forming the flower, we have three kinds 

 occupying different positions on the stem in the higher plants. Briefly 

 describe these. 



69. What are bracts ? Give some o eir modifications. 



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