Question

Example of positive geotropism is
A) Closing of flowers
B) Upward growth of stem
C) Downward growth of root
D) Lateral growth of the root

Answer 1

Hint: The plant consists of many plant growth hormones that are responsible for their growth in length. Auxin and cytokinins are the primary hormones. The auxin shows phototropism but the cytokinin is hormones shows geotropism.

Complete Answer:
- Most of the plants grow continuously throughout their lives, the same as the other multicellular organisms. The plant grows through a combination of cell division and cell growth.
- The cell growth means the increase in the size of the plant and the cell division means the increase in the number of plant cells. As the plant grows in size the cell of the plant becomes specialized into different cell types because of cellular differentiation.
- Meristem is the key to continuous repairing and growth of the plants. It is a type of tissue that is composed of undifferentiated cells that can continue to differentiate and divide. The apical meristem is present in the tip or the apex of the bud and the root that allows the growth of stem and root in length and flowers and leaves to differentiate.
- But do you ever think why the stem moves upward and the root grows in down direction, this is because of the geotropism.
- Now, geotropism is the response of the plant towards gravity. Further it is divided into negative geotropism and positive geotropism.
- The negative geotropism means the movement of plants against gravity and the positive geotropism means the movement of plant parts towards gravity.
- For example; root shows positive geotropism but the primary stem shows negative geotropism. Therefore, from the given option the closing of the flower shows positive geotropism as it is in downward direction.

Thus, the correct answer is ‘A’ Closing of flowers.

Note: The increase in length is considered as the primary growth of a plant but the increase in diameter is considered as the secondary growth of the plant and it does not depend on geotropism or phototropism phenomenon. Else, it depends on the addition of xylem and phloem tissue in the vascular cambium.