This lesson is only available to users who have subscribed to the Biology course. Please log in, or click here if you would like to gain access to the full course.
Introduction to the lesson
Water is not the only substance that the plant needs in order to survive. There are many different mineral ions which are necessary in the processes of the plant. These are transported by phloem tissue. As in the last lesson, try to relate the function of phloem with its structure.
Transport of mineral ions
Read the section “Transport of mineral ions” on p.146 of your text book.
Learning Activity 1
Answer the following questions in your exercise book.
- List mineral ions that plants need to complete their nutrition
- Describe how mineral ions are transported in plants
Translocation
Read the section "Translocation" in your text book (p.146).
Learning Activity 2
Answer the following questions in your exercise book.
- Answer Question 7.10 (p.146).
Sieve tubes and sieve elements
Read the section "sieve tubes and sieve elements" (p.147).
Learning Activity 3
Answer the following questions in your exercise book.
- Study Fig. 7.30 and Fig. 7.31 (p.147-148).
- Using the text and the diagram in Figure 7.30, describe a phloem sieve element
- What is the function of the phloem sieve element?
Companion cells
Read the section "Companion cells" in your text book (p.147).
Learning Activity 4
Answer the following questions in your exercise book.
- Using the text and the diagram in Fig. 7.30, describe a phloem companion cell
- What is the function of the companion cell?
- Draw and label a diagram of a sieve element and companion cell
The contents of phloem sieve tubes
Read the section "The contents of phloem sieve tubes" (p.148-149).
Learning Activity 5
Answer the following questions in your exercise book.
- Study Table 7.3 on p.149.
- Copy this table into your exercise book but add another column in which you give the origin of the substance
- Answer Question 7.11 on p.149.
- Describe “clotting” in plants.
- Describe how aphids are used to collect phloem sap (See Fig. 7.32)
- Study Fig. 7.33 to see how sugar maple is collected. You may want to research this method further via the internet.
How translocation occurs
Read the section "How translocation occurs" in your text book (p.149-151).
Learning Activity 6
Answer the following questions in your exercise book.
- Study Fig. 7.34 on p.150.
- Notice the terms source and sink, also notice the processes marked in purple
- Answer Question 7.12 on p.150.
- Study Fig. 7.35 on p.151.
- Describe how sucrose is loaded into phloem
- Describe how sucrose is unloaded from the phloem
Differences between sieve tubes and xylem vessels
Read the section “Differences between sieve tubes and xylem vessels” on p.151-152 of your text book.
Learning Activity 7
Answer the following questions in your exercise book.
- Construct a table comparing xylem vessels and sieve tubes. Try to make it as detailed as possible. Include diagrams and annotations. (cf. Question 7.13 on p.152).
Definitions and review
Definitions
- Translocation
- Assimilates
- Sieve elements
- Companion cells
- Sieve plate
- Phloem sap
- Source
- Sink
Mindmap
Add this section to your chapter seven mindmap