Botany U208-100 Survey of Botany (2007)

BotanyU208-100 Surveyof Botany (2007)

Part1 (True/False Questions) and Part 2: Multiple-Choice Questions

  1. T

  2. T

  3. F

  4. F

  5. T

  6. T

  7. T

  8. T

  9. F

  10. F

  11. T

  12. T

  13. F

  14. T

  15. T

  16. F

  17. F

  18. T

  19. F

  20. F

  21. D

  22. C

  23. C

  24. D

  25. E

  26. C

  27. A

  28. B

  29. E

  30. A

  31. C

  32. D

  33. E

  34. B

  35. C

  36. A

  37. D

  38. D

  39. B

  40. B

  41. E

  42. D

  43. A

  44. A

  45. D

  46. A

  47. A

  48. C

  49. D

  50. B

  51. A

  52. E

  53. D

  54. A

  55. D

  56. B

  57. E

  58. B

  59. C

  60. A

Part 3: Essay Section

Q1. Describe how a molecule of water is transported from the soil to the top of a giant redwood tree.

Water is an essential element to the growth of any plant. This is in regardless of the plant size or height. For this reason, plants have a significant system to absorb, store, transport, and utilize water. A tall tree like a giant redwood tree has the ability to transport water molecule from the soil all the way to its branches and leaves. To understand the process, one needs to understand the plumbing of the plant. Every plant consists of networks of conduits that comprises of phloem and xylem tissues. Both the phloem and xylem tissues spread throughout the plant from the roots, to the stem, branches, and leaves. Xylem is responsible for transporting water to all parts of the tree that is, from the soil, to the roots, stem, and leaves. They start in the roots, transect up through the trucks as they branch off into branches, and into the leaves. Indeed, water transportation in plants is a complex phenomenon. The primary driving force of water transportation in the plant is the transpiration of water from its leaves. This is the process where the water evaporates from the plants through specialised openings commonly found in leaves. The process creates a negative water vapour, and pulling the water from the vascular tissue and the xylem into the leaves replacing the water that had previously transpired from the leaves. The process then spread all through the xylem of the leaf and to the rest of the xylem columns of the plant. Similarly, the process extends to the xylem of the roots through the xylem tubing due to the cohesive forces. Eventually, the negative water pressure occurs in the roots resulting to an increase of water uptake from the soil to the roots, braches, and leaves.

Q3. Describe a dichotomous key and tell how it is used to identify organisms

Dichotomous key is a device used to identify anonymous organism to a certain level of classification for instance, genus, order, family, or species. It helps the scientists to identify an unknown organism by answering questions that have two answers.

A dichotomous key consists of series of two statements that characterises an organism. In each step, the user makes a choice between two options. As the user selects one option about the characteristics of the organism, the option leads to a new branch of the key. Every key comprises of several couplets. A couplet is a set of mutually exclusive statement in a dichotomous key. The first statement in a couplets leads to the second subsequent couplet, and the process continues until the identification of the specimen. The user follows a particular path of the key. First, the path begins with a question. The answer is either “yes” or “no” or “true” or “false,” and it leads to the next step. The user keeps answering the questions until he or she identifies the organism.

Q5. Explain how knots in a piece of lumber are formed.

Knots are the most regular defects in lumber. A knot is an imperfection in a piece of a wood that causes lumps and holes in a tree. In most cases, knots are due to natural growth of the tree or due to fungal infections. Though at sometime they signify beauty, knots affect the technical characteristics of the wood. In a longitudinal view, a knot appears like a roughly circular piece of wood. A knot can only occur when a tree is still in the growth process. It occurs in a dormant bud or on a base of a side branch. There are different of knots due to different causes. As a tree grows, its truck circumference increases. As a result, growing truck overtakes the growing branches on it. Consequently, knots emerge around these branches and forms truck materials. In most cases, as branches continue to grow, they form solid and tight knots, which consist of living wood. The knot is normally tougher than the other part of the wood, and form a bulge from its centre.

Additionally, a knot is formed if a branch is injured, or dies while still joined to the growing tree. In this case, a loose knot emerges as the truck circumference increases. Unlike the tight knot, the loose knot consists of a black plug of decaying or dead material. Since the material in the centre of the knot is loose, it is easy to remove it. This leaves an empty hole surrounded by tough truck.

Besides, excessive pruning is also another source of knot formation. In the case where many branches are cut down during pruning, a tree may forms sprouts such as epicormic sprouts and bole sprouts at the base of the branches. The tree truck overgrows the sprouts forming knots. Several epicormic sprouts results to multiple knots in the pruned areas. Moreover, a fungus infection such as black knot disease is also another cause of knot formation. Elongated dark knots in the woody portions identify the disease, and it commonly occurs on the twigs and smaller branches. Nevertheless, the disease can spread to other bigger branches and trucks if left untreated hence, knot formation.

6. Explain why plants look green.

Plants are green due the chlorophyll pigment that absorbs red and deep-blue light, and the reflected sunlight spectrum causes the plant to appear green. Furthermore, the chlorophyll pigment inside chloroplasts in plants is green hence, the plants are green. Chloroplasts are the tiny organelles that are responsible for photosynthesis. The chlorophyll pigment main function is to absorb light and convert it into water and oxygen through photosynthesis process. It absorbs blue and red color, and reflects green. Although plant consists of other pigments such as carotenoids&nbsp(orange, yellow, and red) and xanthophylls (yellow), the chlorophyll pigment is more prominent. Therefore, the plants are green.