Question

Which group of plants evolved during the Mesozoic Era and is dominant today? A) gymnosperms C) ginkgoes B) angiosperms D) algae

Short answer

B) Angiosperms.

Step-by-step solution

Understand the Mesozoic Era

The Mesozoic Era is known as the "Age of the Dinosaurs" and spans from about 252 to 66 million years ago. This era is significant in the history of plant evolution due to the initial appearance and diversification of major plant groups.

Identify Key Plant Groups from the Mesozoic Era

During the Mesozoic Era, several plant groups evolved including gymnosperms, angiosperms, and ginkgoes. Algae existed before this era and continued to thrive, but they did not dominate terrestrial ecosystems.

Analyze Dominance in Modern Times

In today's ecosystems, angiosperms (flowering plants) are the most diverse and ecologically dominant group of plants. They are widespread and contribute significantly to terrestrial ecosystems.

Conclusion Based on Evolutionary History

Angiosperms evolved during the late Mesozoic Era and have become the dominant plant group today due to their varied adaptations such as flowers and fruit.

Key concepts

Plant Evolution

The history of plants is a fascinating journey of adaptation and survival across millions of years. During the Mesozoic Era, a significant evolution of plant life occurred. This era, often termed as the "Age of the Dinosaurs," was a period of dynamic environmental changes, which created opportunities for the evolution of new plant groups. Some of the key plant groups that originated in the Mesozoic Era include gymnosperms and angiosperms.

Gymnosperms were one of the earliest seed plants to emerge during this time. They have naked seeds, which mean their seeds are not enclosed in fruits. This group includes conifers, cycads, and ginkgoes. However, while gymnosperms were dominant throughout the early phases of the Mesozoic Era, the eventual evolutionary triumph belonged to another group. Angiosperms, or flowering plants, started to appear in the later part of this era and rapidly became widespread.

The evolution of plants did not stop here. The emergence of angiosperms brought a revolutionary change in the plant landscape. They developed flowers, which were instrumental in reproduction, often involving insects and other animals in the pollination process. These innovations allowed angiosperms to thrive and diversify into every conceivable habitat on Earth.

Angiosperms

Angiosperms, also known as flowering plants, are a revolutionary plant group that transformed the Earth's flora. They first appeared during the late Mesozoic Era and quickly became prevalent due to their unique adaptations.

• Flowers: Unlike gymnosperms, angiosperms produce flowers, which are specialized structures for reproduction. The diversity in flower forms allows for efficient pollination by wind, water, or animals.
• Fruits: Angiosperms enclose their seeds within fruits, providing protection and aiding in seed dispersal.
• Growth Forms: They exhibit a wide range of growth forms, including trees, shrubs, and herbs, allowing them to occupy various ecological niches.

These characteristics enable angiosperms to dominate modern ecosystems. Today, they are the most diverse group of plants, with over 300,000 species. They account for a major portion of the world's plant biodiversity, significantly influencing the structure and function of most terrestrial ecosystems.

Dominant Plant Groups

In the context of plant evolution, dominance refers to the plant group's ability to occupy a vast array of environments and establish a significant presence in ecosystems. Plant groups that have become dominant over time have often introduced notable adaptations.

Historically, gymnosperms were among the first seed plants to dominate during the early Mesozoic Era, taking advantage of their seed-based reproduction and tough, resinous forms to survive various climates. However, gymnosperms began to decline as new plant groups evolved.

The emergence of angiosperms marked a turning point. With their diverse structures and reproductive strategies, they surpassed gymnosperms to become the most dominant group during the Cenozoic Era. This dominance is visible today as angiosperms cover much of the planet. Their diverse forms, ranging from grasses in savannahs to towering hardwoods in forests, illustrate their unparalleled success in the plant kingdom.