Archaeplastida and Land Plant Adaptations

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Questions and Answers

What is the primary role of sporopollenin in charophytes?

It allows for water absorption.

It provides structural support.

It prevents zygotes from drying out. (correct)

It aids in photosynthesis.

Which characteristic is shared between land plants and charophytes?

Production of multicellular gametangia. (correct)

Presence of true roots.

Production of seeds.

Presence of vascular tissue.

What is the process of alternation of generations in land plants characterized by?

Successive multicellular haploid and diploid stages. (correct)

Haploid gametes produced via meiosis.

A single diploid phase.

Three distinct life stages.

Which of the following is NOT one of the four key traits that distinguish land plants from charophytes?

Presence of chlorophylls a and b. (D) Signup and view all the answers

What role did symbiotic associations with fungi play in the life of early land plants?

They enabled nutrient absorption without roots. (B) Signup and view all the answers

Which statement best describes the gametophyte in the plant life cycle?

It alternates with the sporophyte generation. (D) Signup and view all the answers

Why are land plants referred to as embryophytes?

Due to the dependency of the embryo on the parent plant. (C) Signup and view all the answers

Which of the following statements is true regarding charophytes and land plants?

Charophytes and land plants share a common ancestor. (A) Signup and view all the answers

Which of these groups contains glaucocystophytes or glaucocystoids?

Archaeplastida (C) Signup and view all the answers

What is the primary reason why land plants are referred to as embryophytes?

Their embryos are dependent on the parent plant for nutrients. (A) Signup and view all the answers

Which of these is NOT a key trait that distinguishes land plants from their charophyte ancestors?

Presence of chloroplasts (A) Signup and view all the answers

What is the role of sporopollenin in charophytes and land plants?

To prevent the zygote from drying out (C) Signup and view all the answers

Which of the following provides the most compelling evidence for the evolutionary relationship between charophytes and land plants?

The similarity in the structure of their flagellated sperm (C) Signup and view all the answers

Which of these is a challenge faced by plants moving to land?

Exposure to herbivores and pathogens (A) Signup and view all the answers

What is the significance of the apical meristems in land plants?

To allow for continuous growth and development of the plant (C) Signup and view all the answers

Study Notes

Archaeplastida

Archaeplastida contains descendants from endosymbiotic cyanobacteria with chloroplasts
Glaucophytes, also known as glaucocystophytes/glaucocystids, are a small group of unicellular algae found in freshwater and moist terrestrial environments
These were present during the Proterozoic era but have decreased in abundance compared to other eras
Glaucophytes are also known for their unique chloroplast structure preserving some ancient cyanobacteria traits.

Adaptations Enabling the Move to Land.

Charophytes have a durable polymer called sporopollenin that prevents zygotes from drying out
Moving onto land offered charophyte ancestors more sunlight, more CO2, nutrient-rich soil, and fewer herbivores/pathogens.
Land presented challenges, including water scarcity and a lack of structural support.

Morphological and Molecular Evidence

Many land plant characteristics also appear in various algal clades, mostly algae
Land plants share several traits with charophytes, which include:
- Chlorophylls a and b
- Cellulose
- Structure of flagellated sperm
- Formation of sporopollenin

Land Plants Evolved from Green Algae.

Green algae/Glaucophyta relatives called Charophytes seem to be the closest relatives of land plants.
290,000 living species of plants
Comparisons of both nuclear and chloroplast genes demonstrate that charophytes are possibly the closest living relatives of land plants
Note that land plants did not necessarily evolve from modern charophytes but share a common ancestor with modern charophytes.

Four Key Traits in Land Plants (Absent in Charophytes)

Alternation of generations (with multicellular, dependent embryos)
Walled spores produced in sporangia
Multicellular gametangia
Apical meristems
Symbiotic relationships between fungi and the initial land plants aided in the obtaining of nutrients for plants not having true roots.

Alternation of Generations and Multicellular, Dependent Embryos.

Plants alternate between two multicellular stages during a reproductive cycle called alternation of generations.
The gametophyte is haploid and creates haploid gametes by mitosis.
Fusion of the gametes results in the diploid sporophyte, which creates haploid spores by meiosis
Land plants are called embryophytes due to the embryo's dependence on the parent.

Two Types of Gametophytes

The diploid generation is called the sporophyte
The haploid generation is called the gametophyte
As plants evolved, the sporophyte tissue became dominant. This can be witnessed in examples such as mosses and vascular plants. The gametophyte is dominant in some primitive plants .

Derived Traits of Plants

Accumulated derived traits aided in the survival of plants on land and potentially opened the way for plant colonization
Protection from dehydration (cuticle)
Protection from predators (secondary compounds)
Eventually, water, mineral, and nutrient transport (xylem/tracheids and phloem/plumbing). Vascular tissue allowed enhanced internal transport.

Viridiplantae

Viridiplantae includes the largest amount of genetic diversity among plant-like organisms
Includes green algae, ancestors to land plants. Green algae includes Glaucocystophytes and diverse lineages.

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Description

Explore the fascinating world of Archaeplastida and their significant adaptations for life on land. This quiz delves into the traits shared between land plants and their algal ancestors, highlighting the importance of morphological and molecular evidence. Understand how these early life forms transitioned from aquatic to terrestrial environments and the challenges they faced.