Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Autotrophic Nutrition: Green plants are called autotrophs because they prepare their own food from simple inorganic substances like carbon dioxide () and water ().
Photosynthesis: This is the process by which green plants synthesize food (glucose) in the presence of sunlight and chlorophyll. The raw materials required are , , sunlight, and chlorophyll.
Chlorophyll: It is the green pigment present in the leaves (specifically in chloroplasts) that captures the energy of sunlight to drive the process of photosynthesis.
Stomata: These are tiny pores present on the surface of leaves through which exchange of gases ( and ) takes place. They are surrounded by guard cells.
Transport of Water and Minerals: Water and minerals are absorbed by the roots and transported to the leaves through pipe-like vessels called the xylem.
Products of Photosynthesis: The primary product is a simple carbohydrate called glucose (), which is later converted and stored as starch. Oxygen () is released as a byproduct.
Heterotrophic Nutrition in Plants: Some plants lack chlorophyll and depend on others for food. These include: 1. Parasites (e.g., Cuscuta), 2. Insectivorous plants (e.g., Pitcher plant), 3. Saprotrophs (e.g., Fungi/Mushroom), and 4. Symbiotic plants (e.g., Lichens).
Nitrogen Fixation: Plants cannot absorb atmospheric nitrogen () directly. Bacteria like Rhizobium, living in the root nodules of leguminous plants, convert atmospheric nitrogen into soluble forms that plants can use.
📐Formulae
💡Examples
Problem 1:
Explain why the leaf of a plant turns blue-black when treated with iodine solution after being exposed to sunlight.
Solution:
The leaf turns blue-black because of the presence of starch.
Explanation:
During photosynthesis, plants produce glucose (), which is then stored in the leaves as starch. Iodine acts as an indicator for starch; when it comes into contact with starch, a chemical reaction occurs that results in a blue-black color.
Problem 2:
How does a Pitcher plant obtain nutrients even though it is green and can perform photosynthesis?
Solution:
The Pitcher plant traps and digests insects to fulfill its nitrogen requirements.
Explanation:
Pitcher plants usually grow in soil that is deficient in nitrogen. While they can produce carbohydrates through photosynthesis (as they have chlorophyll), they need to consume insects to obtain the essential nitrogen () required for the synthesis of proteins.
Problem 3:
In a Lichen, what is the nature of the relationship between the Alga and the Fungus?
Solution:
It is a Symbiotic relationship.
Explanation:
In Lichens, the fungus provides shelter, water, and minerals to the alga. In return, the alga (which contains chlorophyll) prepares food by photosynthesis and provides it to the fungus. Both organisms benefit from each other ( interaction).