"The Growth of Plants" Life of Angiosperms PPT Courseware 6

"The Growth of Plants" Life of Angiosperms PPT Courseware 6

Think about it and discuss it (page 96)

A well-growing rye plant has about 14 million roots, and its total length is 600 kilometers. These roots have a total of 15 billion root hairs, with a total length of 10,000 kilometers. Accurate calculations show that the total area of ​​this rye plant is 130 times the area of ​​stems and leaves. What does this phenomenon mean for Rye's life?

Rye has a large number of roots and a large total area, which can effectively fix the plant body and absorb water and inorganic salts.

growth of young roots

The short section from the top of the root to the root hairs is called the root tip.

The root tip is the fastest growing part of the young root.

Experiment: Observe the structure of root hairs and root tips

1. First observe the young roots directly with the naked eye and find the white "fuzz" growing on the young roots. This is the root hair. Look closely at the root hairs through a magnifying glass.

2. Observe the permanent sections of the root tip through a microscope to see what are the characteristics of the cells in different parts of the root tip.

2. Branches develop from ______ (page 98)

Structure of leaf buds (lengthwise section)

1. What develops into stems is ______; what develops into leaves is ______; what develops into lateral buds is ______;

2. Because the leaf bud has such a structure, it can develop into ______ in the future.

Branches develop from buds, but do all buds develop into branches?

Classification of buds:

1. According to different locations, it can be divided into:

Terminal bud: The bud at the top of the main trunk or the top of a side branch

Lateral buds: buds on the side of the main trunk or side branches

2. According to different development results, it can be divided into:

Leaf buds: develop into leaves and stems

Flower bud: develops into flower

Mixed buds: can develop into leaves or flowers

3. Plant growth requires nutrients

Whether it is an increase in the number of cells or an increase in cell volume, nutrients need to be continuously replenished: water, inorganic salts and organic matter.

Nutrients needed for plant growth

Organic matter produced by leaf photosynthesis

Inorganic matter (water, inorganic salts) absorbed by roots from soil

The three inorganic salts most needed by plants: nitrogen, phosphorus, and potassium

You know I know

1. Different stages of plant growth require different amounts of inorganic salts.

2. In addition to nitrogen, phosphorus and potassium, plants also need many other types of inorganic salts. For example, if there is a lack of boron-containing inorganic salts, rapeseed will only bloom but not bear fruit.

3. Do not apply too much fertilizer at one time. Excessive application of chemical fertilizers will cause soil hardening, "seedling burning" and even plant death. In addition, pay attention to watering when fertilizing to facilitate the absorption and transportation of fertilizer.

4. Chemical fertilizers in farmland entering waters will cause nutrient enrichment!

Class exercises

1. The formation of a large number of root hairs at the root tip is beneficial to ( )

A. Root absorption B. Root stability

C. Root fixation D. Root support

2. The main part of the roots that absorbs water and inorganic salts is ( )

A, root cap B, elongation zone C, meristematic zone D, mature zone

3. Transplanted cucumber seedlings always have a lump of soil at their roots. The purpose is ( )

A. Protect young stems B. Protect root hairs

C. Prevent water evaporation D. Prevent wilting

4. The reason why perennial woody stems become thicker year by year is ( )

A. Phloem cells are constantly dividing. B. Xylem cells are constantly dividing.

C. Cambium cells continue to divide D. Xylem cells continue to grow

do you know

1. Have you ever seen animals given injections and infusions? Try to answer the following questions.

(1) What substances may be contained in the liquid injected into the plant? What effect can it have?

(2) Which type of tissue of the tree should the needle used for infusion be inserted into?

2. Nong Yan said: "The success or failure of harvest depends on water; the harvest of more or less depends on fertilizer." Does this statement conform to the principles of scientific farming? Why?

(Use the knowledge we have learned today to explain whether this sentence is scientific.)

3. A certain part of the stem of a roadside tree has been traumatized and has exposed xylem. Can the exposed xylem be thickened? Why?

4. Why can the stems of some plants continue to become thicker, while others cannot?

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For more information about the PPT courseware "The Growth of Plants in the Lifetime of Angiosperms", please click the "Growth of Plants in the Lifetime of Angiosperms" ppt tag.

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