Plants:

1. Major Plant Groups and How They Reproduce

a) Angiosperms (Flowering Plants)

Features: Have flowers, fruits, and seeds enclosed inside fruit. Have roots, stems, and leaves.

Reproduction:

Flowers contain male (stamen) and female (carpel) parts.

Pollination: transfer of pollen from stamen to stigma (by wind, insects, etc.).

Fertilisation: sperm in pollen fuses with egg in ovary.

The ovule becomes the seed, and the ovary becomes the fruit.

Examples: Roses, sunflowers, peas, apples.

b) Conifers (Gymnosperms)

Features: Produce cones, not flowers. Have needle-like leaves to reduce water loss.

Reproduction:

Male cones make pollen; female cones contain ovules.

Wind carries pollen to female cones.

Fertilisation occurs → seeds form on cone scales (not enclosed in fruit).

Examples: Pine, fir, spruce trees.

c) Ferns

Features: Have roots, stems, and leaves but no seeds. Reproduce with spores on the underside of fronds (leaves).

Reproduction:

Spores fall to the ground → grow into a small gametophyte.

Sperm swims to egg in water → fertilisation → new fern grows.

Examples: Bracken, maidenhair fern.

d) Mosses

Features: Small, soft plants that grow in damp places. No true roots (have rhizoids).

Reproduction:

Use spores.

Need water so sperm can swim to the egg.

Examples: Cushion moss, peat moss.

e) Liverworts

Features: Flat, leaf-like plants found in wet, shady areas.

Reproduction:

Use spores.

Can also reproduce asexually by fragments breaking off and growing into new plants.

Examples: Marchantia.

2. Main Plant Organs and Their Functions

Organ Main Function(s) Extra Details

Roots Anchor plant; absorb water and minerals from soil; sometimes store food. Root hairs increase surface area for absorption.

Stems Support the plant; hold up leaves, flowers, and fruits; transport water, nutrients, and sugars. Xylem carries water up; phloem carries food down/up.

Leaves Photosynthesis (make food); gas exchange; water loss (transpiration). Have chloroplasts containing chlorophyll to capture sunlight.

Flowers Reproduction; produce seeds. Contain male (stamen) and female (carpel) parts; attract pollinators with color and scent.

3. Root Systems: Taproot vs Fibrous

Taproot System

Structure / Features:

One main thick root growing deep into the soil (primary root).

Smaller lateral roots branch off the main root.

Found mostly in dicot plants (two seed leaves).

Functions:

Anchorage: Holds large plants firmly in the ground.

Absorption: Reaches deep water and minerals.

Storage: Stores starch and nutrients (used during drought or growth).

Advantages:

Reaches deep water during dry conditions.

Very strong support for tall plants.

Stores food for later use (helps in survival).

Limitations:

Cannot absorb surface water quickly after rain.

Hard to transplant — root can break.

Struggles in hard, shallow soils.

Examples:

Carrot, beetroot, dandelion, rose, mango, radish.

Fibrous Root System

Structure / Features:

Many thin, branching roots spread out near the surface.

No single main root.

Found mostly in monocot plants (one seed leaf).

Functions:

Anchorage: Forms a dense network that grips the soil.

Absorption: Quickly takes up water and nutrients near the surface.

Prevents erosion: Roots hold soil together.

Advantages:

Excellent at absorbing rainwater quickly.

Prevents soil erosion.

Easy to transplant.

Grows quickly and spreads wide.

Limitations:

Cannot reach deep underground water.

Weaker anchorage for tall plants.

Stores very little food.

Examples:

Grass, rice, wheat, maize (corn), onion, palm.

Comparison Table

Feature Taproot Fibrous Root

Main root One main root Many thin roots

Depth Deep Shallow

Storage Yes (food stored) Little or none

Water access Deep soil water Surface water

Anchorage Strong Moderate

Soil erosion control Weak Strong

Found in Dicots Monocots

Examples Carrot, rose, beetroot Grass, rice, maize

4. Seed Germination

Steps in Germination:

Water absorption (imbibition): Seed takes in water and swells.

Enzymes activate: Stored food in the seed is broken down for energy.

Radicle (young root) emerges first to anchor and absorb water.

Shoot grows upward toward light.

First leaves open and begin photosynthesis.

Conditions Required:

Water – to soften the seed coat and activate enzymes.

Oxygen – for respiration to release energy.

Warmth – enzymes work best at certain temperatures.

(Some seeds also need light or darkness depending on species.)

Examples:

Beans, peas, and grasses all germinate when given water, warmth, and air.

5. Photosynthesis

Word Equation:

Carbon dioxide + Water → Glucose + Oxygen

(with light energy and chlorophyll)

Chemical Equation (optional for high level):

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

Where it Happens:

In the chloroplasts of leaf cells.

Chlorophyll, the green pigment, captures light energy from the Sun.

How Plants Capture Light:

The broad surface of leaves helps capture more sunlight.

Chlorophyll absorbs mainly red and blue light, converting light energy into chemical energy.

This energy is used to join carbon dioxide (from air) and water (from roots) into glucose — the plant’s food.

Oxygen is released as a waste gas through small openings called stomata.

Why Photosynthesis Is Important:

Provides food (glucose) for the plant.

Produces oxygen for animals and humans.

Forms the base of all food chains.