The activity of `alpha`-amylase in the endosperm of a germinating seed of barley is induced by

Options

A. ethylene
B. cytokinin
C. IA A
D. gibberellin

Explanation

To answer the question regarding the induction of alpha-amylase activity in the endosperm of a germinating seed of barley, we can follow these steps:

### Step 1: Understand the Context
The question is about the germination of barley seeds and the role of specific enzymes during this process. During germination, seeds utilize stored nutrients to support growth.

**Hint:** Consider the role of hormones in plant growth and development, particularly during germination.

### Step 2: Identify the Key Enzyme
Alpha-amylase is a hydrolytic enzyme that breaks down starch into sugars, which are essential for the energy needs of the germinating seed.

**Hint:** Recall the function of alpha-amylase and its significance in seed germination.

### Step 3: Recognize the Role of Plant Hormones
Gibberellic acid (GA) is a plant hormone known to promote growth and is particularly important in the germination process. It induces the synthesis of hydrolytic enzymes, including alpha-amylase.

**Hint:** Think about how hormones can influence enzyme activity and synthesis in plants.

### Step 4: Connect the Dots
The synthesis of alpha-amylase occurs in the aleurone layer of the barley grain, which is stimulated by gibberellic acid. Once synthesized, these enzymes are transported to the endosperm where they perform their function.

**Hint:** Consider where in the seed the enzyme is produced and where it acts.

### Step 5: Conclude the Answer
Based on the information gathered, we conclude that the activity of alpha-amylase in the endosperm of a germinating seed of barley is induced by gibberellic acid.

**Final Answer:** The activity of alpha-amylase in the endosperm of a germinating seed of barley is induced by gibberellic acid.