Plant Biology: Germination and Growth Stages

Study Notes

Seeds contain an embryo, stored food, and a protective seed coat.
Germination requires specific environmental conditions, including adequate moisture, warmth, and oxygen.
Water triggers the metabolic processes within the seed, activating enzymes that break down stored food.
The radicle (embryonic root) emerges first, followed by the plumule (embryonic shoot).
Seedlings develop their own roots and leaves to begin photosynthesis and obtain nutrients.

This stage involves the development of leaves, stems, and roots.
Plants use photosynthesis to convert light energy into chemical energy in the form of sugars (food).
Growing shoots elongate, becoming taller and producing additional leaves through cell division and elongation.
Roots grow down into the soil, absorbing water and dissolved nutrients.
Lateral buds differentiate and develop into branches, increasing the plant's surface area for light interception.
The vascular system transports water and nutrients throughout the plant.

This stage leads to the production of flowers, fruits, and seeds for the next generation.
Flowers are reproductive structures housing male and/or female reproductive organs.
Pollination involves the transfer of pollen from the anther to the stigma.
Fertilization occurs when the pollen fuses with the ovule, forming a seed.
The ovary develops into a fruit containing the seeds.
Many factors, including environmental cues (photoperiod, temperature, etc.), trigger reproductive development in plants.

Flowers typically consist of sepals (protective outer layers), petals (for attracting pollinators), stamens (male parts including anther and filament), and carpels (female parts including stigma, style, and ovary).
Different flower structures and arrangements are crucial for specific pollination strategies.

Pollination can be carried out by wind, water, or animals.
Wind pollination is common in grasses and trees, relying on the wind to transfer pollen.
Water pollination is less common but occurs in some aquatic plants.
Animal pollination, including insects, birds, and bats, is highly specialized and often involves color, scent, and nectar rewards.

Fruits protect the seeds and aid in their dispersal.
Fruit development follows the fertilization process, with the ovary expanding into a fleshy or hard fruit.
Various dispersal mechanisms exist, such as wind, water, animal ingestion, and explosive mechanisms, which increase the plant's chances of colonizing new areas.

Many plants have a life cycle that involves distinct vegetative and reproductive phases, with the specific timings and processes varying among different species.
Some plants are annuals (complete their life cycle within one year), biennials (complete their life cycle within two years), or perennials (live for more than two years).
Specific factors determine the life cycle characteristics and patterns of growth and development of a plant.