Question:

Differentiate between: (a) Hypocotyl and Epicotyl (b) Coleoptile and Coleorrhiza (c) Integument and Testa (d) Perisperm and Pericarp

Answer:

(a) Hypocotyl: The part of the stem of a germinating seedling between the radicle and the cotyledons.

Epicotyl: The part of the stem of a germinating seedling above the cotyledons.

(b) Coleoptile: The sheath that covers the embryonic shoot of a grass seedling.

Coleorrhiza: The sheath that covers the embryonic root of a grass seedling.

(c) Integument: The outermost layer of the seed coat, which encloses the embryo.

Testa: The innermost layer of the seed coat, which encloses the endosperm.

(d) Perisperm: The nutritive tissue of a seed, which is derived from the maternal tissue of the ovule.

Pericarp: The outer layer of the fruit wall, which encloses the seed.

Question:

With a neat, labelled diagram, describe the parts of a typical angiosperm ovule.

Answer:

Neatly Labelled Diagram of an Angiosperm Ovule:

1. Integument
2. Chalaza
3. Funiculus
4. Micropyle
5. Megasporangium (nucellus)
6. Embryo Sac
7. Polar Nuclei
8. Antipodal Cells
9. Egg Cell
10. Synergids

Question:

With a neat diagram explain the 7-celled, 8-nucleate nature of the female gametophyte.

Answer:

1. The female gametophyte is composed of a seven-celled, eight-nucleate structure.

2. The seven cells are arranged in a linear fashion with four cells on the top and three cells on the bottom.

3. Each cell has two nuclei, one from the egg and one from the central cell.

4. The egg cell is the largest and is located at the top of the structure, followed by the two synergid cells.

5. The three antipodal cells are located at the bottom of the structure.

6. The central cell is located in the middle of the structure and contains two nuclei.

7. The eight nuclei are distributed among the seven cells, with the egg cell containing four nuclei, the two synergid cells containing two nuclei each, the three antipodal cells containing one nucleus each, and the central cell containing two nuclei.

Diagram:

Egg Cell

Question:

If one can induce parthenocarpy through the application of growth substances, which fruits would you select to induce parthenocarpy and why?

Answer:

1. Parthenocarpy is the process of developing fruits without fertilization.

2. In order to induce parthenocarpy, growth substances such as gibberellic acid, auxins, and cytokinins can be applied.

3. Fruits that are most commonly used for parthenocarpy are bananas, pineapples, grapes, tomatoes, and cucumbers.

4. Bananas are a good choice for parthenocarpy because they are easy to grow, have a high yield, and have a high market value.

5. Pineapples are a good choice for parthenocarpy because they are easy to grow, have a high yield, and have a sweet flavor.

6. Grapes are a good choice for parthenocarpy because they are easy to grow, have a high yield, and have a sweet flavor.

7. Tomatoes are a good choice for parthenocarpy because they are easy to grow, have a high yield, and have a wide range of uses in cooking.

8. Cucumbers are a good choice for parthenocarpy because they are easy to grow, have a high yield, and have a mild flavor.

Question:

Name the parts of an angiospermic flower in which development of male and female gametophyte take place.

Answer:

1. Anther: The part of an angiospermic flower where male gametophyte development takes place.

2. Stigma: The part of an angiospermic flower where female gametophyte development takes place.

Question:

Arrange the following terms in the correct developmental sequence: Pollen grain, sporogenous tissue, microspore tetrad, pollen mother cell, male gametes.

Answer:

Pollen Mother Cell → Microspore Tetrad → Sporogenous Tissue → Pollen Grain → Male Gametes

Question:

Why is apple called a false fruit? Which part(s) of the flower forms the fruit?

Answer:

Answer:

1. Apple is called a false fruit because it is not formed from the ovary of a flower.
2. The parts of the flower that form a fruit are the ovary, the style and the stigma.

Question:

Explain the role of tapetum in the formation of pollen-grain wall.

Answer:

1. Tapetum is a layer of cells that lines the inner wall of the anther of a flower.

2. The tapetum plays an important role in the formation of pollen-grain wall.

3. The tapetum secretes special substances that act as a glue to bind the cells of the pollen grain wall together.

4. The tapetum also produces enzymes that break down the cell wall of the pollen grain, allowing for the formation of a new wall.

5. The tapetum also helps to provide nutrition to the developing pollen grain, which helps in the formation of a strong wall.

6. Finally, the tapetum helps to protect the developing pollen grain from environmental stresses, such as temperature, humidity, and UV radiation.

Question:

What are chasmogamous flowers? Can cross-pollination occur in cleistogamous flowers? Give reasons for your answer.

Answer:

Answer:

1. Chasmogamous flowers are flowers that open fully and have exposed reproductive organs, allowing for cross-pollination.

2. Cross-pollination cannot occur in cleistogamous flowers as they are self-pollinating, meaning they do not open and their reproductive organs are not exposed.

Question:

Mention two strategies evolved in flowers to prevent self-pollination in flowers.

Answer:

1. Physical Isolation: Many flowers have evolved a physical barrier to prevent self-pollination. This barrier may be in the form of a long floral tube, a short style or a thickened stigma. This prevents the pollen from the same flower from reaching the stigma.

2. Self-incompatibility: Many flowers have evolved a system of self-incompatibility in which the pollen from the same flower is not able to fertilize the ovules of the same flower. This is achieved by the presence of specific proteins or enzymes in the pollen and stigma which interact and prevent the formation of a fertilized egg.