IGCSE Biology 0610 - 1.3 Features of Organisms

Objective: Classify organisms using the features identified for the plant kingdom.

Introduction

Plants are a diverse group of organisms with a wide range of adaptations that allow them to survive in various environments. Understanding these features is crucial for classifying plants into different groups.

Key Features of Plants

Plants share several fundamental features that distinguish them from other organisms. These features are key to their classification.

• Cell walls: Plant cells have rigid cell walls made of cellulose, providing support and structure.
• Chloroplasts: These organelles contain chlorophyll, which is essential for photosynthesis.
• Photosynthesis: Plants use photosynthesis to convert light energy into chemical energy in the form of glucose.
• Reproduction: Plants can reproduce both sexually (through seeds) and asexually (through runners, bulbs, etc.).
• Growth: Plants exhibit continuous growth throughout their lifetime, particularly in length and width.
• Transport systems: Vascular tissues (xylem and phloem) transport water and nutrients throughout the plant.
• Adaptations: Plants have evolved various adaptations to suit different environments, such as different leaf shapes, root systems, and stem structures.

Plant Classification Based on Features

Plants can be classified based on various features, including the presence or absence of seeds, the number of cotyledons in the embryo, and the type of vascular tissue.

Non-vascular Plants (Bryophytes)

These plants lack vascular tissues (xylem and phloem). They are typically small and grow in moist environments.

Feature	Presence	Example
Vascular Tissue	Absent	Mosses, Liverworts, Hornworts
Seeds	Absent
Dominant Generation	Gametophyte

Seedless Vascular Plants

These plants have vascular tissues but do not produce seeds. They are typically larger than non-vascular plants.

Feature	Presence	Example
Vascular Tissue	Present	Ferns, Horsetails, Club Mosses
Seeds	Absent
Dominant Generation	Sporophyte

Seed Plants

These plants produce seeds, which protect the embryo and provide nourishment.

Feature	Presence	Example
Vascular Tissue	Present	Gymnosperms, Angiosperms
Seeds	Present
Dominant Generation	Sporophyte

Gymnosperms

These plants have "naked seeds" – seeds that are not enclosed within an ovary. They are typically cone-bearing.

Feature	Presence	Example
Seeds	Present (naked)	Conifers (pines, firs), Cycads, Ginkgo
Flowers/Cones	Cones

Angiosperms

These plants have seeds enclosed within an ovary, which develops into a fruit. They are the most diverse group of plants.

Feature	Presence	Example
Seeds	Present (enclosed in fruit)	Flowering plants (trees, shrubs, herbs)
Flowers/Fruits	Flowers and fruits

Conclusion

By understanding the key features of plants, we can effectively classify them into different groups based on their reproductive strategies and structural adaptations. This knowledge is fundamental to understanding plant diversity and evolution.