Plant Structure and Life Cycle

Study Notes

Plant Structures and Functions

Chloroplasts contain chlorophyll and are responsible for photosynthesis
Cell walls are made of cellulose and provide structural support
Specialized reproductive organs include flowers and cones
Vascular tissues (xylem and phloem) facilitate water and nutrient transport

Alternation of Generations in Plants

Involves a cycle between a haploid gametophyte generation (producing gametes) and a diploid sporophyte generation (producing spores)
Allows for both sexual and asexual reproduction

Transition from Water to Land in Plants

Major adaptations include:
- Development of a cuticle to prevent water loss
- Roots for anchorage and absorption of water and nutrients
- Vascular tissues for internal transport

Leaf and Plant Structures

Cuticle: reduces water loss
Stomata: regulate gas exchange
Chloroplasts: contain chlorophyll for photosynthesis
Cell walls: provide structural support
Grana: sites of photosynthesis
Stroma: involved in the synthesis of organic molecules

Evolution of Plant Structures

Order of appearance: cuticle, stomata, roots, seeds, and finally flowers

Sporophyte and Gametophyte Generations

In bryophytes, the gametophyte is dominant
In ferns and gymnosperms, the sporophyte is dominant
In angiosperms, the gametophyte generation is greatly reduced

Characteristics Unique to Animals

Multicellularity
Heterotrophy
Locomotion
Nervous system
Sexual reproduction

Cladogram and Phyla

A cladogram can be used to recognize which phyla possess a given characteristic

Transition from Water to Land in Animals

Key adaptations include:
- Development of limbs for movement
- Lungs for respiration
- Skin adaptations to prevent desiccation

Symmetry in Animals

Bilateral symmetry offers better mobility, efficient hunting, and directional movement compared to spiral symmetry
Bilateral symmetry is associated with triploblastic animals (three germ layers: ectoderm, endoderm, and mesoderm)
Radial symmetry is associated with diploblastic animals (two germ layers: ectoderm and endoderm)

Protostomes and Deuterostomes

Protostomes: blastopore develops into the mouth, and the anus forms later (e.g., mollusks, annelids, and arthropods)
Deuterostomes: blastopore develops into the anus, and the mouth forms later (e.g., echinoderms and chordates, including vertebrates)

Asexual Reproduction

Animals: budding (e.g., Hydra), fragmentation (e.g., starfish), and parthenogenesis (e.g., some lizards)
Plants: vegetative propagation (e.g., runners in strawberries), fragmentation (e.g., spider plants), and budding (e.g., yeast)

Sexual Reproduction

Advantages: genetic diversity, elimination of deleterious mutations through recombination
Disadvantages: energy and time required to find a mate and produce offspring, risk of producing unfit offspring, and potential for genetic variability

Description

Learn about the unique structures of plants, including chloroplasts, cell walls, and vascular tissues, as well as the alternation of generations in their life cycle. Understand the role of gametophyte and sporophyte generations in plant reproduction. Test your knowledge of plant biology!