"Green Plants and the Water Cycle of the Biosphere" PPT Courseware 5

Description

"Green Plants and the Water Cycle of the Biosphere" PPT Courseware 5

learning target :

Describe the basic structure of green plant leaves

Explain the opening and closing mechanism of stomata

Explain the role of green plants in the water cycle of the biosphere

Plants absorb and transport water

There are white "fuzz" --- root hairs on the young roots. What is the significance of a large number of root hairs for water absorption?

Increase the surface area for roots to absorb water and improve the efficiency of roots in absorbing water.

Where does the water absorbed by the plants go?

A sunflower consumes about 30 kilograms of water in its lifetime; an acre of rice field consumes about 300,000 kilograms of water during the entire growth period; and a corn plant consumes about 250 kilograms of water from emergence to harvest.

Take a guess

Why do plants need so much water?

Where does about 99% of the water absorbed go? Where does the water escape from?

plant transpiration

What is the process of transpiration and where does it occur? (Describe the process by which transpiration occurs)

What is the significance of transpiration?

The concept of transpiration

Transpiration is the process by which water is lost from the surface of living plants (mainly leaves) to the atmosphere in the form of water vapor.

Observe the structure of the leaves

Purpose requirements:

1. Practice slicing with your bare hands.

2. Understand the structure of blades.

3. Draw the epidermal cells and guard cells of the leaves.

Materials and tools: slightly.

Method steps:

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

2. Observe the structure of the leaves.

3. Observe the upper and lower epidermis of the leaves.

Guard cells are half-moon-shaped, with thicker walls on the side closer to the stomata and thinner walls on the side farther from the stomata. When the guard cells absorb water and expand, the stomata open; when the guard cells lose water and shrink, the stomata close.

When the sun rises and the temperature rises, the stomata open and the plant's transpiration increases, lowering the temperature of the leaf surface and preventing the leaves from being burned by the sun. At the same time, with the loss of water, the power of upward transport of water increases, which promotes plant roots to absorb water, allowing plants to carry out vigorous life activities. When night falls, the temperature drops, photosynthesis, transpiration, etc. gradually weaken or even stop. At this time, most stomata are also closed.

The meaning of transpiration:

It can promote the transportation of water and inorganic salts in the body and ensure the needs of various tissues and organs for water and inorganic salts.

In hot summer, transpiration can reduce the temperature of the leaf surface and prevent plants from being burned due to excessive temperatures.

Discussion: 1. What role do green plants play in the water cycle?

Green plants absorb water from the soil through their roots, and most of the water is lost through transpiration, promoting the water cycle in the biosphere.

Discussion: 2. If there were no green plants on the earth, would the water cycle proceed?

Without green plants, the water cycle can still take place. Water vapor evaporated from oceans and lakes enters the atmosphere and forms clouds, which then form rain and snow, and then return to the ocean or land. But without green plants, the water cycle in the biosphere will be affected to a certain extent. For example, rainfall on land will decrease; surface runoff caused by rainfall will increase and speed up, etc.

practise

1. Determine whether the following statements are correct. Mark “√” if they are correct and “×” if they are incorrect.

(1) Plants lose a lot of water through transpiration, which is a waste. ( )

(2) The stomata of plants are very small, so the water lost through the stomata is very small. ( )

(3) In plants, water flows to higher places, which is mainly driven by transpiration. ( )

test you!

1. The structure of a leaf is composed of ___________ and ___________.

2. Stomata are the "____________" for plants to lose water through transpiration, and also the "____________" for gas exchange. The morphological changes of _________ can control the opening and closing of stomata.

3. Plants participate in the water cycle of the biosphere through ________.

4. Stomata are the gateway for plants to lose water through transpiration and are also windows for gas exchange.

7. Blade structure

(1). The structure of leaves includes: epidermis, mesophyll, and veins.

(2). The window for gas exchange between leaves and the outside world is: ____. Its closing is controlled by ________. The characteristics of this cell structure are:

The cell wall thickness is uneven, with the outer wall of the stomatal cavity being thicker and the inner wall of the dorsal stomatal cavity being thinner.

(3) The protective organization in the picture is: ________.

The nutrient tissue is ____________.

Belonging to the transmission organization is:___________.

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;

For more information about the "Water Cycle of Green Plants and Biosphere" PPT courseware, please click the "Water Cycle of Green Plants and Biosphere" ppt tag.

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Update Time: 2024-07-24

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

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