November 10, 2017

Biology: The Characteristics of Seed Plants

They have vascular tissue and use seeds to reproduce. They have leaves, stems, and roots.
They have complex life cycles include the sporophyte and gametophyte.

Vascular Tissue

Source: SCQ
Most seed plants live on land. The thick walls of the cells in the vascular tissue help support the plants. In addition, water, food, and nutrients are transported throughout the plants in vascular tissue.

Two types of vascular tissue, phloem through which food moves. Water and nutrients travel in the vascular tissue called xylem. The plant's roots absorb water and nutrients from the soil.


Seeds are structures that contain a young plant inside a protective covering. Seed plants do not need water in the environment to reproduce. This is because the sperm cells are delivered directly to the regions near the eggs. After sperm cells fertilize the eggs, seeds develop and protect the young plant from drying out.

Source: Wikipedia
A seed has three important parts - and embryo, stored food, and a seed coat.
The young plant that develops from the zygote, or fertilized egg, is called the embryo. The embryo already has the beginnings of roots, stems, and leaves.

Food is stored inside one or two seed leaves, cotyledons.

Outer covering of a seed is called the seed coat.

Seed Dispersal

To develop into a new plant, a seed needs light, water, and nutrients.

The scattering of seeds is called seed dispersal.


Source: The k8 school
Germination is the early growth stage of the embryo. It begins when the seed absorbs water from the environment.

First, the embryo's roots grow downward, then its leaves and stem grow upward.


Source: Britannica
Leaves capture the sun's energy and carry out the food-making process of photosynthesis.

The Structure of a Leaf

Source: Wikipedia
The leaf's top and bottom surface layers protect the cells inside. Between the layers of cells inside the leaf are veins that contain xylem and phloem. The underside of the leaf has small openings, or pores, called stomata.

The stomata open and close to control when gases enter and leave the leaf.

The Leaf and Photosynthesis

Source: Wikipedia
The photosynthesis occurs in the chloroplasts of plant cells. The cells that contain the most chloroplasts are located near the leaf's upper surface, where they are exposed to the sun.

Carbon dioxide enters the leaf through open stomata. Water, which is absorbed by the plant's roots, travels up the stem to the leaf through the xylem. During photosynthesis, sugar and oxygen are produced from the carbon dioxide and water.
The sugar enters the phloem and then travels throughout the plant.

Controlling Water loss

Source: Wikipedia
The process by which water evaporates from a plant's leaves is called transpiration.


Source: Wikipedia
The stem carries substances between the plant's roots and leaves. The stem also provides support for the plant and holds up the leaves so they are exposed to the sun. In addition, some stems, such as those of asparagus, also store food.

The Structure of a Stem

Source: Wikibooks
Herbaceous stems are soft. Woody stems are hard and rigid.

Herbaceous and woody stems consist of phloem and xylem tissue as well as many other supporting cells.

Woody stems have bark, which helps protect the cells inside it, and inner layers of heartwood for additional support. Inside the outer bark layer is the phloem. Inside the phloem is a layer of cells called the cambium. Cambium divide to produce new phloem and xylem.

In the center of the stem is material called the pith. Pith stores food and water.

Annual Rings

Source: Picky Wallpaper
Annual rings are made of xylem. Xylem cells that form in the spring are large and have thin walls because they grow rapidly. They produce a wide, light brown ring. Xylem cells that form in summer grow slowly and, therefore, are small and have thick walls. They produce a thin, dark ring. One pair of light and dark rings represents one year's growth.


Source: LMC lambark
Roots anchor a plant in the ground and absorb water and nutrients from the soil.

Types of Roots

Source: The Visual Dictionary 
Two types of root systems: taproot and fibrous.

Taproot is a long, thick main root.

Fibrous root systems consist of several main roots that branch repeatedly to form a tangled mass of roots and soil.

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