Question

Which are the external conditions required for seed germination?
A. Oxygen, carbon dioxide and suitable temperature
B. Oxygen, light and suitable temperature
C. Light, moisture and suitable temperature
D. Oxygen, moisture and suitable temperature

Answer 1

After fertilization in an angiosperm plant, ovary becomes fruit and fertilized ovule becomes seed. A seed contains an embryo and the food. The seed germination grows into a new plant.

Complete answer:
Seed germination is the resuming growth of the embryo resulting in the rupture of the seed coat and the emergence of the young plant under favourable conditions. Seed germination depends on a number of several external and internal factors. In nature, seed must wait for the combination of these factors for its germination. Seed germination occurs only when there is a combination of favourable conditions.
There are two types of germination, hypogeal and epigeal germination.
In hypogeal germination, the cotyledons do not come out above the soil surface, only plumule emerges above the ground. For example paddy, onion, wheat and pea seeds.
In epigeal germination, the cotyledon comes out above the soil surface. Examples are most of the dicots and pine seeds.
Following are the external conditions required for the seed germination are:
Oxygen, moisture and suitable temperature.
Oxygen:
Oxygen is necessary for the germination because respiration increases sharply during seed germination. Since respiration is essentially for oxidation of food to produce energy. Thus, an adequate supply of oxygen is a must for the germination.
Moisture:
Moisture or Water is a basic requirement for germination. It is essential for enzyme activation, breakdown, translocation and use of reserve storage materials.
Suitable temperature:
Seed germination involves many enzymatic reactions. Enzyme actions need optimum temperature. The optimum temperature for most of the seeds is between 15 to 30 °C. Soil factor: Soil structure, soil texture and soil temperature influences seed germination.

So, the correct answer is option D.

Note: In the process of seed germination, the seed’s role is that of the reproductive unit. It contains life and ensures the continuity of all plant species. Since the seed role stands, seed germination remains a key to modern agriculture.