Question

Activities happening during seed germination are listed below. Select the group having the correct order of activities-
(A). Initiation of embryo growth
(B). Resumption of metabolic activity in the rehydrated seed
(C). Rupture of seed coat and the emergence of seedling
(D). Absorption of water by the dry seed
Choose the correct answer from the options given below:

• A. (B), (D), (A), (C).
• B. (D), (B), (C), (A).
• C. (D), (B), (A), (C).
• D. (C), (B), (D), (A).

Hint:

Remember the three phases of germination water uptake:
Phase I: Imbibition (D - water absorption).
Phase II: Lag phase (B - metabolic activation).
Phase III: Radicle growth and emergence (A and C - visible growth and rupture).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Seed germination is a complex physiological and biochemical process that transforms a dormant, dehydrated embryo into an actively growing seedling.
This process follows three distinct physiological phases, characterized by changes in water uptake and metabolic activity.

Step 2: Detailed Explanation:
Let us organize the steps of seed germination in chronological order:
1.

Step 1: Imbibition (D): Germination begins with the physical absorption of water by the dry seed (imbibition, Phase I of water uptake).
This is a passive process driven by the highly negative water potential of the dry seed, which causes the seed to swell and softens the seed coat.
2. Resumption of Metabolic Activity (B): Upon rehydration (Phase II, the lag phase), the seed resumes its metabolic activity.
Hydration activates pre-existing enzymes and stimulates the synthesis of new proteins and plant hormones (like gibberellins).
Respiration rates increase, and food reserves (starch, lipids, or proteins) are hydrolyzed into soluble, transportable sugars and amino acids to nourish the embryo.
3.

Step 2: Initiation of Embryo Growth (A): During Phase III, cellular division and elongation begin within the embryo.
The embryonic cells enlarge, and the radicle begins to elongate toward the basal end of the seed.
4.

Step 3: Seed Coat Rupture and Emergence (C): The elongating radicle exerts pressure on the surrounding seed coat, eventually rupturing it.
The radicle emerges first to establish root contact with the soil, followed by the elongation of the hypocotyl or epicotyl to push the shoot upward, completing visible germination.
Thus, the correct sequence of events is (D) \( \rightarrow \) (B) \( \rightarrow \) (A) \( \rightarrow \) (C).

Step 3: Final Answer:
The correct physiological order of germination events is (D), (B), (A), (C), corresponding to option (C).