Test: Nutrition in Plants- 2 - UPSC MCQ

During the process of photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose (carbohydrate) and oxygen. The glucose produced is then stored in the form of starch. Therefore, during photosynthesis, oxygen is indeed released as a byproduct, and starch, which is a carbohydrate, is produced. The presence of starch in leaves indicates that photosynthesis has occurred.

The given equation represents the process of photosynthesis, in which plants use carbon dioxide and water in the presence of sunlight and chlorophyll to produce carbohydrates (glucose) and release oxygen. 

When an insect lands in a pitcher plant, the plant's lid closes, trapping the insect inside. The inner surface of the pitcher is lined with hair that further entangles the insect, preventing its escape. The plant then secretes digestive juices to break down the insect, and the nutrients from the insect are absorbed by the plant. This process is characteristic of insectivorous plants, which capture and digest insects to obtain essential nutrients. Thus, the correct answer is:
(C) The pitcher plant’s lid closes, trapping the insect, which is then digested by digestive juices and absorbed for nutrients.

Nitrogen in the soil is converted into a usable, soluble form by bacteria, such as Rhizobium, which helps plants utilize nitrogen for growth.

Guard cells surround the stomata and control their opening and closing, which regulates gas exchange and water loss in leaves.

Saprotrophs, such as fungi, absorb nutrients from dead and decaying matter, while parasites depend on living hosts for their nutrition.

Leaves are known as the food factory of plants because they contain chlorophyll and are the primary site of photosynthesis where food is synthesized.

In lichens, a chlorophyll-containing alga and a fungus live together, sharing shelter and nutrients. The alga prepares food through photosynthesis, while the fungus provides water and minerals. This mutually beneficial relationship, where both organisms share resources, is called a symbiotic relationship. Thus, the correct answer is:

Fertilizers are added to soil to provide essential nutrients like nitrogen, potassium, and phosphorus, which help in plant growth and soil fertility.

Nitrogen-fixing bacteria are crucial for plants because they convert atmospheric nitrogen into a form that plants can absorb and use. These bacteria, often found in the roots of legumes, provide plants with essential nitrogen that is needed for protein synthesis and overall growth, thus reducing the need for synthetic nitrogen fertilizers.