Question

nitrogen cycle

1. what percentage of the atmosphere is nitrogen?

a. 50%
b. 78%
c. 90%
d. 65%

1. what is the primary role of nitrogen in plant growth?

a. it helps with photosynthesis
b. its essential for protein formation
c. it increases soil acidity
d. it promotes flowering

1. which form of nitrogen is preferred by annual plants?

a. ammonium
b. nitrate
c. urea

Explanation:

Step1: Recall atmospheric composition

Nitrogen makes up about 78% of the Earth's atmosphere.

Step2: Know plant - nitrogen role

Nitrogen is a key component of amino - acids which are building blocks of proteins, crucial for plant growth.

Step3: Understand plant nitrogen preference

Annual plants generally prefer nitrate as a nitrogen source as it is more readily available and easily assimilated compared to ammonium and urea in most soil conditions.

Answer:

1. B. 78%
2. b. It's essential for protein formation
3. b. Nitrate