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Introduction to the lesson
Stems, roots and leaves are obvious structures of plants. They are the organs of the plant--just the same way as your heart, liver, lungs and kidneys are organs. Thinking about them in this way helps us to remember that they each are composed different types of cells and tissues which work together to perform a specific function. In the next few lessons we will learn a bit more about the functions that these organs perform.
Structure of stems, roots and leaves
Read the section “Structure of stems, roots and leaves” on p.128-134 of your text book.
Learning Activity 1
Answer the following questions in your exercise book.
- What is the difference between organs, tissues and cells? Give an example of each.
- Explain why stems, roots and leaves are considered to be organs.
- Revise the definitions of these terms:
- angiosperms
- monocotyledonous
- dicotyledonous
- herbaceous
- Revise the characteristics of monocotyledonous and dicotyledonous plants.
Practical Investigation: Low-power plan diagrams
- Read the purple Box 7.1 Biological drawing on p.129. Biology has a lot of drawing as part of the study. Biological drawings are not the same as artistic drawing. There are definite rules about biological drawings. (Revise Biological drawings in the IG textbook as well). In Box 7.1, take careful note of the following:
- The guidelines for the quality of your drawing
- Low-power drawing
- High-power drawing
- Guidelines for the quality of labelling
- Study Fig. 7.2 and Fig. 7.3 on p.128. What is meant by a low-power plan?
- Make your own low-power plan from Fig. 7.2 and label your drawing
- Answer Question 7.1 on p.129.
- How does your plan compare?
- Study Fig. 7.5 and Fig. 7.6 on p.130. Make your own low-power plan from Figure 7.5. Label your plan. How does your plan compare to Fig. 7.6?
- Now study Fig. 7.7 and draw a low-power plan from Fig.7.7 and label your plan. Compare your plan with the plan drawn in Fig. 7.8 on p.131.
Practical Investigation: High power drawings
Re-read the section on high-power detail diagrams on p.131 as well as High-power drawing in Box 7.1 on p.129 in your text book.
Epidermis
- Re-read the section on epidermis on p.131
- Draw a high-power detail of a transverse section of leaf epidermis – see Fig. 7.9
- List the characteristics and function of epidermal cells.
Parenchyma
- Re-read the section on parenchyma on p.132.
- Draw a high-power detail of a transverse section of parenchyma- see Fig. 7.10
- List the characteristics and function of parenchyma cells.
Collenchyma
- Re-read the section on collenchyma on p.132.
- Draw a high-power detail of a transverse section of collenchyma from Fig. 7.7 (Draw three cells in total).
- List the characteristics and function of collenchyma cells.
Endodermis
- Re-read the section on endodermis on p.132.
- Draw a high-power detail of a transverse section of endodermis from Fig. 7.11 (Draw three cells in total).
- List the characteristics and function of endodermis cells.
Mesophyll
- Re-read the section on mesophyll on p.132.
- Draw a high-power detail of a transverse section of (a) palisade mesophyll and (b) spongy mesophyll) from Figure 7.12 (Draw three cells in total).
- List the characteristics and function of mesophyll cells
Pericycle
- Re-read the section on pericycle on p.132.
- List the characteristics and function of pericycle cells.
Vascular tissue
- Describe the structure and function of the different types of cells that make up xylem
- Describe the structure and function of the different types of cells that make up phloem
Definitions and review
Definitions
- Monocotyledons
- Dicotyledons
- Epidermis
- Cuticle
- Stomata
- Root hairs
- Parenchyma
- Collenchyma
- Spongy mesophyll
- Palisade mesophyll
- Pericycle
- Sclerenchyma
- Sieve tube elements
Mindmap
Add this section to your chapter seven mindmap.