WHAT ARE THE DIFFERENCES BETWEEN VASCULAR AND NON- VASCULAR PLANTS?

Transcription

1 WHAT ARE THE DIFFERENCES BETWEEN VASCULAR AND NON- VASCULAR PLANTS? Let s take a closer look. What makes them different on the outside and inside?

2 Learning Intentions To understand how vascular plant cells are specialized and organized for the intake, movement and loss of water from a plant Success Criteria I can explain how the root and shoot systems are effective in transporting water through a plant I can explain the structural and functional differences between xylem and phloem I know the difference between vascular and non-vascular plants

3 Take a close look. SEE IF YOU CAN OBSERVE THE DIFFERENCES BETWEEN THE TWO PLANTS

4 Vascular Non Vascular

5 Vascular Non Vascular

6 Vascular Non Vascular

7 Vascular Non Vascular

8 Vascular Non Vascular

9 WHAT ARE THE DIFFERENCES? Vascular Plants Has roots Has stems Has leaves Has vascular bundles Can transport water Larger in size Is better able to store water in cells Non Vascular Plants No roots No stems No leaves No vascular bundles Are unable to transport water Smaller in size Must live in damp conditions

10 Think about the largest tree you have ever seen. How do you think the tree moves water and food through that very tall trunk? A tree is an example of a vascular plant. They have a system of tissues within them that carry water and food throughout the plant. These tissues are found in the roots, stems, and leaves of the plant. Vascular tissue ensures that each organ the leaves, stems, roots, flowers and seeds receive what they need. The organs are grouped as systems. Plants have two systems: Shoot system: all parts of the plant found above ground responsible for transportation, absorption, reproduction and photosynthesis Root system: all parts of the plant found below ground responsible for absorbing water and nutrients from the soil

11

12 VASCULAR TISSUE The vascular tissues are divided into two types based on what they transport. The phloem are vessels on the outer layer of the stem that transport food materials such as sugars from the leaves, where they are produced, or from storage tissues, to the rest of the plant. If a tree is cut, you can often see sap seep out of the tree, and this is the contents of the phloem. If you have ever had maple syrup, it is the processed form of the sap that is found in the phloem of maple trees. The second type of vascular vessel is the xylem; these are the vessels that transport water throughout the plant. The xylem vessels carry water from the roots up the plant and to the leaves. Not only do vascular tissues help plants move water and food more efficiently throughout the plant, they also make it possible for the plant to grow larger. By having these vessels, plants can move necessary supplies farther and therefore grow larger. These vascular vessels are similar to the closed circulatory system of humans, because both systems transport nutrients and allow the organisms to grow larger due to the ability to transport farther.

13 XYLEM See figure 3.6 pg.72 Water enters the roots by the process of osmosis. Dissolved ions enter via diffusion and active transport. Xylem is made up of two types of cells: tracheids and vessel elements. Water exits the xylem vessels via stomata small holes on the surface of the leaves Water is evaporated off the surface of the leaves through the process transpiration (like perspiration), this drives the constant upward movement of water Water is continually being sucked from the roots and transported to the leaves this is called the transpiration stream. This process, where the water is pulled up vertically through the xylem, is called transpirational pull. Water particles are adhesive (stick to the xylem vessel) and cohesive (stick together) so if some move, they all move. This allows water to reach the leaves at the top of a very tall tree.

14

15 STOMATA The carbon dioxide that plants need to photosynthesise enters through the stomata (singular stoma). This is the site of gas exchange. It is also where water exits. Why are most stomata found on the lower surface of the leaves?

16 Stomata are surrounded by two guard cells. A stoma is open when guard cells are turgid and closes when these cells are flaccid Read page 73 and determine what causes stomata to close.

17 PHLOEM The movement of organic materials (sugars) around the plant is called translocation Not all cells are capable of photosynthesis as then do not all contain chloroplasts however all plant cells require glucose for cellular respiration The product of photosynthesis is glucose, however it is converted to sucrose for transport and starch for storage. Sucrose requires active transport from the phloem into cells. During the day a plant both photosynthesises and respires During the night they can only respire as they do not have access to sunlight to photosynthesise

18 a) Loss of water from xylem through transpiration and use in metabolism pulls water through xylem vessels b) Sugars are pushed down the phloem. Sugar moves from a region of high pressure near its site of production to regions of low pressure where sugars are used.

19 STRUCTURAL AND FUNCTIONAL DIFFERENCES BETWEEN XYLEM AND PHLOEM Xylem is a dead tissue (the cells have lost the nucleus, organelles and cytoplasm), while phloem is alive (some cells remain fully functional). Xylem transports water and dissolved minerals around the plant (from roots to leaves). Phloem conducts dissolved sugar around the plant from where it is made to where it is needed.

20

21

22 TEST YOUR KNOWLEDGE: 1. Which vessel is damaged in the process of ringbarking and why does this lead to the death of a plant? 2. How is water transported around a plant? 3. How are sugars transported around a plant? 4. How are the xylem and phloem arranged in plant roots? 5. Explain how a plant increases its surface area for water absorption. HOMEWORK: Plant tissues worksheet