"Plant Stems and Material Transport" PPT

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"Plant Stems and Material Transport" PPT

Part 1: The structure of the stem

1. Classification of stems

According to form:

①Erect stem

Features: The stem is relatively strong and can stand upright.

Camphor tree, sugar cane

②Twining the stem

Features: Use the stem itself to wrap around other objects and rise up

morning glory, ivy

③ stolons

Features

The stem is soft and lies flat on the ground.

Strawberries, sweet potatoes

④ Climbing stem

Features

Grow upward by means of abnormal structures (such as tendrils) on stems and leaves.

Grapes, cucumbers

Difference: According to the development of wood in the stem, the stem can be divided into herbaceous stem and woody stem. The woody part of the herbaceous stem accounts for very little and is relatively fragile. The stem becomes inverted after the plant dies. Plants with herbaceous stems are called herbs and are often called "grasses". Most monocots are herbs. Most of the woody stem is composed of xylem, which is very hard. The stem can still stand upright after the plant dies. Plants with woody stems are called woody plants and are often called "trees".

2. Stem structure

Outside: The cells are arranged __________, the intercellular spaces are relatively __, and play the role of __________,

Inner side: phloem

Bast fiber: supportive

Sieve tubes: transport organic matter

Xylem: located in the __________ of the stem, including:

①The larger cells are ____ and have the function of __________;

②The smaller cells are __________ (hard and have strong supporting force)

Plant stems and material transport PPT, part 2: annual rings

1. The formation of annual rings

Internal factors: caused by the intensity of cambium splitting activity.

External factors: cyclical changes in climate.

2. Determine tree age based on annual rings

3. Determine the climate environment at that time based on the growth rings

4. Determine the direction based on annual rings

The side with sparse lines faces south, and the side with dense lines faces north.

5. Determine the environmental pollution at that time based on the "spots" on the annual rings

Pollutants in the environment are sucked into and fixed in the growth rings of different years. By analyzing the growth rings through advanced technology, we can know the nature and extent of the pollution.

Plant stems and material transport PPT, part three: summary

1.Classification of stems

stem shape

Upright stem The stem is relatively strong and can stand upright.

Stolons lie flat on the ground and spread around with adventitious roots.

Wrap the stem, use the stem itself to wrap around and rise

Climbing stem Uses tendrils to climb something up

stem composition

woody stem

Herbaceous stem

2. Structural characteristics of dicotyledonous plant stems:

Structure of dicotyledonous plant stems

bark

Outer bark protection

inner bark

(The inside is the phloem)

Sieve tubes transport organic matter

Bast fiber

Cambium cells can divide and proliferate

xylem

Catheters carry water and inorganic salts

Wood fiber increases stem strength

Keywords: Zhejiang Education Edition eighth grade science PPT courseware for the second volume free download, plant stems and material transport PPT download, .PPT format;

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Update Time: 2024-09-30

This template belongs to science courseware Zhejiang Education Edition Eighth Grade Science Volume 2 industry PPT template

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