Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Adaptation is the process where a plant or animal becomes better suited to its environment through structural or functional changes.
Hydrophytes are plants adapted to live in aquatic environments (). They have features like aerenchyma (air cavities) for buoyancy and a waxy coating to prevent decay.
Mesophytes are plants that grow in conditions with moderate supply. They have well-developed root systems and stomata usually located on the underside of the leaves.
Xerophytes are plants adapted to survive in habitats with very little , such as deserts. They exhibit modifications like thick cuticles, sunken stomata, and succulent stems to store water.
Transpiration is the loss of vapor from the aerial parts of the plant. Xerophytes minimize this to conserve moisture, while Hydrophytes have limited or no stomata on submerged parts.
In Xerophytes like Opuntia, the stem becomes flattened and green to perform photosynthesis, a condition known as phylloclade, while leaves are reduced to spines to prevent water loss.
📐Formulae
💡Examples
Problem 1:
Why do the leaves of the Lotus plant (a Hydrophyte) float on the surface of , and why is the upper surface waxy?
Solution:
The leaves contain large air spaces called aerenchyma for buoyancy, and the upper surface is coated with a waxy layer.
Explanation:
Aerenchyma allows the leaf to stay afloat to receive sunlight for photosynthesis. The waxy coating prevents from clogging the stomata (which are on the upper surface) and prevents the leaf from rotting.
Problem 2:
Identify the type of plant that has 'sunken stomata' and explain its advantage.
Solution:
Xerophytes (e.g., Pine, Nerium).
Explanation:
Sunken stomata are located deep in the leaf tissue, which creates a pocket of moist air, reducing the diffusion gradient and thereby significantly lowering the rate of transpiration to conserve .
Problem 3:
A plant has a taproot system that goes very deep into the soil. Which category does it likely belong to?
Solution:
Xerophyte.
Explanation:
Xerophytes develop long, extensive root systems to reach deep underground tables in arid regions where the topsoil is dry.