Book cover for Biology

Biology

Sylvia S. Mader, Michael Windelspecht

ISBN #9780078024269

12th Edition

687 Questions

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153,501 Students Helped

Homework Questions

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Summary
Learning Objectives
Key Concepts
Example Problems
Explanations
Common Mistakes

Summary

Chapter 23 explores the evolutionary journey of plants from freshwater green algae to a diverse array of land plants. It highlights the importance of critical innovations such as the protective cuticle, vascular tissue, and the alternation-of-generations cycle. These adaptations not only enabled the successful colonization of terrestrial habitats but also laid the foundation for the diversification of major plant groups, including Bryophytes, Lycophytes, Pteridophytes, and Seed Plants, significantly impacting natural ecosystems and agricultural practices.

Learning Objectives

1

Describe the evolutionary transition from freshwater green algae to terrestrial land plants.

2

Explain the critical innovations such as the protective cuticle, vascular tissue, and alternation-of-generations cycle.

3

Analyze the evolutionary development of major plant groups including Bryophytes, Lycophytes, Pteridophytes, and Seed Plants.

4

Evaluate the adaptive strategies that enabled plants to colonize and diversify in terrestrial habitats.

Key Concepts

CONCEPT

DEFINITION

Land Plants

Plants that have adapted to live on land with features such as protective cuticles and specialized tissues.

Protective Cuticle

A waxy, waterproof layer on the surface of plant tissues that reduces water loss and provides protection against pathogens.

Vascular Tissue

Specialized tissues (xylem and phloem) that transport water, nutrients, and sugars throughout the plant, enabling it to grow larger and more complex.

Alternation-of-Generations

A reproductive cycle in which plants alternate between a haploid (gametophyte) phase and a diploid (sporophyte) phase, enhancing genetic diversity and adaptability.

Bryophytes

Non-vascular plants, such as mosses, that represent some of the earliest land colonizers, characterized by a reliance on water for reproduction.

Lycophytes

An early group of vascular plants known for having small leaves (microphylls) and simple vascular systems.

Pteridophytes

Vascular plants that developed larger leaves (megaphylls) and more complex reproductive cycles, represented by ferns and their relatives.

Seed Plants

Plants that reproduce using seeds, which provide protection and nourishment to the developing embryo, marking a full adaptation to life on land.

Example Problems

Example 1

Which of these are characteristics of land plants? a. multicellular with specialized tissues and organs b. photosynthetic and contain chlorophylls a and b c. protect the developing embryo from desiccation d. have an alternation-of-generations life cycle e. All of these are correct.

Example 2

Label this diagram of alternation-of-generations life cycle.

Example 3

In the moss life cycle, the sporophyte a. consists of leafy, green shoots. b. is the heart-shaped prothallus. c. consists of a foot, a stalk, and a capsule. d. is the dominant generation. e. All of these are correct.

Example 4

In bryophytes, sperm usually move from the antheridium to the archegonium by a. swimming. b. flying. c. insect pollination. d. wind pollination. e. bird pollination.

Example 5

A small, upright plant that resembles a tiny, upright pine tree with club-shaped strobili and microphylls is a a. whisk fern. b. lycophyte. c. conifer. d. horsetail. e. fern.
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Step-by-Step Explanations

QUESTION

How does the development of a protective cuticle contribute to the successful colonization of land by plants?

STEP-BY-STEP ANSWER:

Step 1: Identify that the protective cuticle is a waxy, waterproof layer present on the surface of leaves and stems.
Step 2: Understand that this layer minimizes water loss by reducing evaporation, an essential feature for survival on dry land.
Step 3: Recognize that it also acts as a barrier against pathogens and environmental stressors.
Final Answer: The protective cuticle is a key adaptation that enabled plants to manage water loss and resist external threats, facilitating their successful colonization of terrestrial habitats.

Protective Cuticle

QUESTION

Describe the significance of vascular tissue in enhancing plant complexity and size.

STEP-BY-STEP ANSWER:

Step 1: Define vascular tissue as a network of specialized cells (xylem and phloem) that transport water, nutrients, and sugars.
Step 2: Explain that the development of vascular tissue allowed plants to efficiently distribute resources to all parts, supporting larger and more complex structures.
Step 3: Discuss how this adaptation enabled plants to colonize diverse and arid environments by ensuring internal water and nutrient balance.
Final Answer: Vascular tissue plays a crucial role in resource distribution within a plant, supporting increased size and complexity and allowing plants to adapt to a variety of terrestrial environments.

Vascular Tissue

QUESTION

How does the alternation-of-generations life cycle benefit plants in their evolutionary journey?

STEP-BY-STEP ANSWER:

Step 1: Define alternation-of-generations as a life cycle that alternates between a haploid (gametophyte) stage and a diploid (sporophyte) stage.
Step 2: Explain that this cycle allows for genetic diversity through sexual reproduction.
Step 3: Highlight how the two distinct phases enable plants to adapt to changing environments by optimizing both reproduction and survival strategies.
Final Answer: The alternation-of-generations cycle enhances genetic diversity and adaptability, providing plants with a robust mechanism to thrive across varying environments.

Alternation-of-Generations

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Common Mistakes

  • Confusing the non-vascular nature of Bryophytes with the vascular systems found in other plant groups.
  • Misunderstanding the alternation-of-generations cycle by assuming it only involves a single phase.
  • Overgeneralizing adaptive traits, such as assuming all land plants possess a protective cuticle or advanced vascular tissue.
  • Underestimating the importance of each evolutionary innovation in the context of plant diversification and adaptation.