"Green Plants and the Water Cycle of the Biosphere" PPT Courseware 2

Description

"Green Plants and the Water Cycle of the Biosphere" PPT Courseware 2

Water is an important component of plants.

When there is sufficient water in the plant, the plant can be stiff and maintain an upright posture; the leaves can stretch, which is conducive to photosynthesis.

Only when inorganic salts are dissolved in water can they be absorbed by the plant body and transported to various organs of the plant body.

Situation import

Information: Someone calculated that a corn plant consumes more than 200 kilograms of water during its lifetime from emergence to fruiting. Only about 2.2 kilograms of this water is used as a component of the corn plant and participates in various physiological processes. Where did the rest of the water go? What significance does this water have to the plants themselves and the natural world?

1. Plants’ absorption and transportation of water

As the saying goes, "the roots are deep and the leaves are flourishing." Where is the main part of the root that absorbs water? How is water transported to other parts of the plant after entering the root?

1. Root absorption of water

The main part of the root that absorbs water: the _______ at the root tip. There is a large amount of _____ growing there, which increases the ______ for the roots to absorb water.

2. Transport of moisture

(1) Experiment: Take a section of _____ stem, put it into water with a few drops of red ink, and irradiate it under ______ for 3 to 4 hours. You will see ______ turn red; cut the stem lengthwise If you turn it on, you will find that ______ turns red.

(2) Duct: It is composed of many ____________ cells. The _______ between the upper and lower cells has disappeared, forming a hollow tube. In addition to the stem, there are also ducts in the ______, which are connected through each other.

(3) Transportation of water and inorganic salts: After roots absorb ______ and _______, they are transported to various parts of the plant through ______ in roots, stems, and leaves.

(4) Pathways for plants to transport substances:

a) Catheter: carries _____ and _____ from bottom to top.

b) Sieve tube: transports _____ produced by photosynthesis of leaves from top to bottom.

Observe the structure of the leaves

What is the main organ through which plants lose water? What is its structure?

1. Practice slicing with your hands and make temporary slices of cross-sections of leaves.

(1)Put the fresh leaves ______ on the small wooden board.

(2) Pinch the side-by-side __________ with your right hand and quickly cut across the leaves.

(3) Every time you make a cut, dip the blade in water and put the cut ______ into the water.

(4) Use a brush to dip a piece of ______ into it to make __________.

2. Blade structure

epidermis

upper epidermis

lower epidermis

There are stomata (more stomata in the lower epidermis)

Mesophyll: vegetative tissue. There are chloroplasts in the mesophyll cells. Their main function is to carry out _______.

Leaf veins: have vessels and sieve tubes, belong to ________, and have transport and support functions.

Stomata is the "portal" through which plants lose water through transpiration and is also the "window" for gas exchange.

ANALYSE information

1. According to scientific calculations, the rainfall in a certain tropical rainforest is 1,950 mm/year, and the transpiration is 1,570 mm/year. Please calculate, what percentage of the rainfall does transpiration account for?

2. As the saying goes: "It's good to enjoy the shade under a big tree."

According to the survey, on a scorching summer day, the temperature in green areas is 0.8°C lower than that in non-green areas, and the temperature in the forest is 1.3°C to 3.2°C lower than the temperature in the courtyard.

What conclusion can you draw from these two pieces of information?

Plant transpiration not only promotes the absorption and upward transport of water and inorganic salts by plants, but also reduces the temperature of plants.

Transpiration can also increase atmospheric humidity, increase precipitation, and participate in the water cycle of the biosphere.

【Cooperation and exchange】

1. When transplanting saplings, flower seedlings and vegetables, why are there lumps of soil at the roots?

Protect root hairs and young roots and improve plant survival rate.

2. Are duct cells living cells? Why?

Ducts are tubes formed by many long, tubular cells with the cell walls disappearing between them. There is no cytoplasm or nucleus, so duct cells are dead cells.

3. Why do we need to cut the leaves into slices before we can observe their structure?

The material to be observed with a microscope must be thin and transparent. The leaves are opaque and cannot be observed. Thin and transparent slices must be made for observation.

4. Functionally speaking, what tissues do the ducts and sieve tubes in the epidermis, mesophyll and leaf veins belong to?

The epidermis is a protective tissue, the mesophyll is a nutritional tissue, and the ducts and sieve tubes in the leaf veins are conductive tissues.

5. In the leaves of land plants, do the upper epidermis and lower epidermis have the same number of stomata? Why?

The lower epidermis of land plants has many stomata, which can reduce water loss.

Keywords: Green Plants and the Biosphere's Water Cycle Teaching Courseware, People's Education Edition 7th Grade Biology PPT Courseware Download, Seventh Grade Biology Slide Courseware Download, Green Plants and the Biosphere's Water Cycle PPT Courseware Download, .PPT format;

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Update Time: 2024-11-13

This template belongs to biology courseware People's Education Edition seventh grade biology volume 1 industry PPT template

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