Module_8_Lecture_Plant_Repro_and_Development_KEY

Plant Reproduction and Development

• Diversity in reproductive strategies reflects evolutionary divergence and adaptation.

A. Sexual Life Cycles

• Draw general sexual life cycles for animals, plants, fungi:

  • Key Terms: meiosis, fertilization, haploid, diploid, sporophyte, gametophyte, dikaryon, alternation of generations.

  • Animals: Begin as diploid zygotes, undergo meiosis to produce haploid gametes, fertilization restores diploid state.

  • Plants: Alternation of generations between gametophyte (haploid) and sporophyte (diploid) phases.

  • Fungi: May form dikaryons (n+n) before meiosis.

C. Reproductive Adaptations

• Examples of adaptations in plants and animals:

  • Spores: Protects genetic material and allows for survival in harsh conditions.

  • Pollen: Enables fertilization without water.

  • Seeds: Support growth in terrestrial environments, include nutrients and a protective coat.

  • Fruit: Aids in seed dispersal, provides protection.

  • Amniotic Eggs: Adaptation in reptiles for life away from water.

• Map adaptations onto phylogenetic tree to understand evolutionary history.

D. Flower Structure and Reproduction

• Relate flower parts to pollen, seed, and fruit production:

  • Pollen: Produced by stamens, essential for fertilization.

  • Seeds and Fruits: Develop post-fertilization, critical for dispersal.

• Discuss plant-animal interactions:

  • Pollinators crucial for reproductive success.

E. Development Patterns Compared

• Plants vs. Animals:

  • Plants exhibit indeterminate growth patterns, where they continuously grow and reproduce.

  • Animals typically follow a determinate growth model with fixed developmental stages.

Importance of Plants

• Supply oxygen and carbon compounds to atmosphere.

• Form basis of terrestrial food chains, numerous food sources derived from plants.

• Regulate biogeochemical cycles in ecosystems:

  • Control carbon exchange with the atmosphere.

  • Influence the hydrological cycle.

  • Affect climate significantly.

Energy Transformation in Plants

1. Electromagnetic to Chemical Energy

• Visible light energy converted to chemical bond energy in glucose:

  • Photosystems capture photons, initiating electron transport chains that generate ATP.

  • Carbon fixation leads to glucose production.

2. Water Movement

• Water uptake through roots, released through stomata.

3. Carbon Movement

• CO2 enters leaves, fixed as glucose and released during cellular respiration.

Alternation of Generations

Key Process Flow in Plants

• Sequence in flowering plants:

  • Correct Sequence: (B) sporophyte – meiosis – spores – mitosis – gametophyte – mitosis - gametes - fertilization – zygote.

Life Forms Classification

• Land Plants categorized by vascular tissue, seeds & flowers:

  • Non-Vascular Plants: Mosses, liverworts, hornworts.

  • Vascular Seedless Plants: Ferns.

  • Gymnosperms: Conifers, cycads, Ginkgo biloba.

  • Angiosperms: All flowering plants, including monocots and dicots.

Gametophyte and Sporophyte Comparison

• Mosses: Dominant gametophyte, reduced attached sporophyte.

• Ferns: Dominant sporophyte with free-living small gametophytes.

• Gymnosperms: Dominant sporophyte with dependent gametophytes.

• Angiosperms: Dominant sporophyte, reduced/dependent gametophyte.

Seed Plants Adaptations

• Pollen: Enables fertilization without water.

• Seeds: Embryo surrounded by nutrient-rich protective coat, key in adaptation to land.

• Pollen grain development through microsporangia, leading to motile gametophytes.

Flower Structure

Key Components:

• Sepals: Protect and enclose flower.

• Petals: Attract pollinators.

• Stamens: Produce pollen.

• Carpels: Produce ovules, site of fertilization.

Pollination and Fertilization

• Pollination: Pollen grain germinates on stigma, pollen tube reaches the ovule.

• Double Fertilization: One sperm fertilizes egg forming zygote (2n) and the other combines with central cell for endosperm (3n).

Fruit Development

• Post-fertilization:

  • Zygote becomes embryo, endosperm develops as food reserve, ovary wall forms fruit.

• Fruits adapted for seed dispersal by wind or animals.

Trivia and Concepts

• Question on Fruit Function: What is the key adaptive function of fruits? (C) Nutrition for animals that disperse seeds; (D) Attract animals for seed dispersal.

Plant Structural Overview

Angiosperm Life Cycle

• Anther, stigma, carpel, ovary, petal interaction in fertilization and seed development.

• Importance of flower structure in reproductive strategies.