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D3.1.12—Seed dispersal and germination

Seed dispersal moves offspring away from parents, while germination requires water, oxygen and suitable temperature to mobilize stored food reserves.

Syllabus
First assessment 2025
Objective
D3.1.12
Level
HL

Exam analysis

Chance of appearing12%of analysed past papers
Latest appearanceMay 2024
Most common paperPaper1
Typical marks1–3

Common command terms

  • Identify
  • Outline

Scoring notes

Common mistake
Listing water, oxygen and temperature without explaining their biological roles.

Recent exam appearances

May 2024Paper2 ["HL"] · TZ13(c)(ii)[ 2 ]D3.1.12—Seed dispersal and germination
May 2024Paper2 ["HL"] · TZ13(c)(i)[ 1 ]D3.1.12—Seed dispersal and germination
May 2023Paper1 ["HL"] · TZ132[ 1 ]D3.1.12—Seed dispersal and germination
May 2022Paper1 ["HL"] · TZ234[ 1 ]D3.1.12—Seed dispersal and germination
November 2021Paper1 ["HL"] · TZ034[ 1 ]D3.1.12—Seed dispersal and germination

Coverage 2013–2024 · Updated 16 Jul 2026

A Fertilized Ovule Becomes a Dispersal-Ready Seed

Flower structure Mature product
zygote embryo root, shoot and cotyledon or cotyledons
fertilized ovule seed containing embryo and food reserve
ovule wall protective seed coat or testa
ovary fruit surrounding or carrying seeds

Wind, water, animals or explosive fruit mechanisms carry seeds away from the parent. Separation reduces competition for light, water, minerals and space and can colonize new sites.

Pollination moves pollen before fertilization. Seed dispersal moves a fertilized, developing offspring after seed formation.

Seeds move away from a parent plant and later take up water, mobilize food reserves and emerge as seedlings.

Dormancy Must End before Germination Conditions Can Act

Dormancy is an internal block to growth in a viable seed; germination is the resumed growth of the embryo using stored food.

Dormancy may persist because the embryo is immature, inhibitory abscisic acid remains, the testa is impermeable, or a species-specific chilling period has not occurred.

External condition Why germination needs it
water rehydrates cells, softens testa and enables metabolic reactions
oxygen supports aerobic respiration and ATP production
suitable temperature permits enzyme-catalysed reserve mobilization and growth

Light is required for germination in some species but not all. Water, oxygen and a suitable temperature are the general conditions emphasized here.

Gibberellin Mobilizes Stored Food for the Growing Embryo

water uptake activates embryo → embryo releases gibberellin → signal reaches food-storage tissue → hydrolytic enzymes such as amylase are produced → starch becomes maltose and then glucose; proteins become amino acids → soluble products move to growing root and shoot

Mobilized product Immediate use
glucose respiration for ATP and carbon skeletons for biosynthesis
amino acids synthesis of enzymes and structural proteins

The seedling depends on stored reserves until leaves expand and photosynthesis supplies enough organic material for independent growth.

Flowering-Plant Reproduction Links Transfer, Recognition and Establishment

pollen production → transfer to stigma → compatibility check → pollen-tube delivery → gamete fusion in ovule → seed and fruit formation → dispersal → dormancy release → germination and reserve mobilization

Transition problem Adaptation
pollen must reach a conspecific stigma pollinator attraction, wind transfer and flower geometry
selfing can reduce variation timing, spatial separation, separate sexes and self-incompatibility
offspring compete with parent seed dispersal
growth begins in poor conditions dormancy and environmental germination requirements

Pollination is gamete delivery, fertilization is nuclear fusion, and dispersal moves the resulting seed. Keep those transitions separate while explaining how each supports successful outcrossing and establishment.

Seed dispersal and germination

[ 6 ]

Outline the metabolic processes that occur in starchy seeds during germination.

Concept essentials

  • Water uptake is the first step that reactivates metabolism in a dry seed.
  • Gibberellin stimulates amylase production during germination of starchy seeds.
  • Cotyledons store reserves used for embryo growth during germination.