Lesson 13 February 4th, 2011

Organs Working Together

Organs that function together form organ systems.

Each organ system consists of a group of organs that work together to carry out specific duties.

Plant Organ Systems A plant has two organ systems:

a shoot system and a root system.

The shoot system is everything that is above ground: the stem, leaves, buds, flowers, and fruits.

The root system is everything underground, as well as aerial roots.

The Shoot System

The functions of the shoot system include

Photosynthesis, Reproduction, Storage, Transport, Hormone production.

The Root System Two primary root system types: Taproot system - Single primary

root dominates over branch roots ( usually found in Gymnosperms and most Dicotyledons)

The Root System Two primary root system types: Fibrous root system – A network of

fine roots with no central dominant root. Fibrous root systems don't go as deep as taproots, but they spread laterally

Plant Organ Systems

Both systems need to work together in the movement of water in the plant

Water enters the root hairs and travels to the xylem. Water is moved against gravity by transpiration

Plant Organ Systems

Transpiration is the evaporation of water through the stomata in the leaves.

As each water molecule evaporates, it creates a transpiration pull on the adjacent water molecules, which pulls the water up the xylem to the leaves. Once the water reaches the leaf, the transpiration pull is enough to move the water from the xylem into the ground tissue.

Plant Organ Systems

http://www.youtube.com/watch?v=mc9gUm1mMzc&NR=1

Plant Organ Systems

The organs of a plant also work together to ensure that the plant survives changes in the environment.

Specialized cells record changes in the exposure to light. When the length of daylight increases, chemical messages are delivered to tissues to stimulate the production of a flower.

In times of drought and excessive heat, a plant may decrease its production of leaves

Questions – hand in for homework1. What are the two organ systems in a

plant?2. What are some of the main functions

of the shoot system in a plant?3. What are the similarities and

differences between the two types of root systems?

4. Explain how a plant is able to get water to the leaves.