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.