"Plant Leaves and Transpiration" PPT courseware

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"Plant Leaves and Transpiration" PPT courseware

Part 1: Structure of leaves

Although the shapes of leaves are diverse, their basic structures are similar. A leaf is composed of petiole and blade, and blade is composed of epidermis, mesophyll and veins. The epidermis is divided into upper epidermis and lower epidermis. The epidermis is composed of a large number of colorless and transparent epidermal cells, which is conducive to the transmission of light and the protection of inner leaf structures.

discuss:

After the roots of the plant absorb water and inorganic salts from the soil, they are transported through the stems to the leaves, flowers, fruits and branches high above. It is estimated that one corn plant consumes four to five hundred kilograms of water from emergence to harvest. According to daily experience, the mass of a mature corn plant is far lower than four or five hundred pounds if all its substances are added up. Then do you know where the water it absorbs goes?

Plant leaves and transpiration PPT, part 2 content: Transpiration

1. The process in which water absorbed by plant roots is emitted from the plant body to the outside of the body in a gaseous state is called transpiration.

Note: About 99% of the water absorbed by the roots is emitted through transpiration.

2. The meaning of transpiration:

⑴ Effectively reduce leaf temperature, allowing plants to perform photosynthesis under strong light without being harmed.

⑵ It is the main driving force for roots to absorb water, which is beneficial to the absorption and transportation of water by plants, and also facilitates the transportation of inorganic salts dissolved in water within the plant body.

Plant leaves and transpiration PPT, part 3 content: thinking and discussion:

1. What will happen to the water column indoors? Why?

--The water column will drop.

--Because the plants will conduct transpiration at this time.

2. If placed indoors in a place exposed to sunlight, what will happen to the water column? Why?

--The water column drops faster.

--Because being in the sun opens the stomata and the temperature rises, the transpiration will be enhanced.

3. What will happen to the water column if it is placed in a dark and humid environment? Why?

--In a humid environment, the mercury column will drop, but very slowly and even unnoticeably.

--Because in a humid environment, the humidity is high, the stomata are not open to a large extent, and the transpiration effect is weak.

4. If you blow the blades with a hair dryer, what will happen to the water column? Why?

--The water column will drop rapidly.

--Because the hair dryer can create a microclimate around the pores

--Water dispersion is fast, the temperature is high, and transpiration will be enhanced.

5. What will happen to the water column when placed under the scorching sun? Why?

--Under the scorching sun in summer, the water column will not shorten.

--Because under the scorching sun in summer, the stomata will close and the transpiration basically stops.

Plant leaves and transpiration PPT, part 4 content: Summary:

1. Transpiration is the process by which plants emit water absorbed by their roots through their leaves into the atmosphere in the form of water vapor. The main organ of plant transpiration is the leaves. The water lost by leaves through transpiration accounts for 99% of the water absorbed by roots, and only 1% is used for various life activities of the plant.

2. The transpiration of plants is affected by factors such as temperature, humidity, light, and wind. As the temperature rises, transpiration is enhanced, but when the temperature is too high, transpiration will stop; when humidity is high, transpiration is weak; when the gas flow rate on the leaf surface is high, transpiration will be enhanced.

Plant leaves and transpiration PPT, Part 5: Apply what you learn:

Question 1: Why do people often say that “it’s good to enjoy the shade under a big tree”?

Because large and leafy trees can block sunlight, the temperature under the trees is relatively low. In addition, the transpiration and photosynthesis of large trees increase the humidity and oxygen content of the surrounding air respectively.

Question 2: When we transplant plants, how do you think we can improve the survival rate?

(1) Transplant with soil and water to enhance water absorption function

(2) Cut off some branches and leaves, shade them from the sun, and try to transplant them in the evening to reduce transpiration and prevent the plants from losing water and dying.

Think: Where on the leaves does water emanate from?

Experiment instructions:

1. Cobalt chloride blue filter paper: If cobalt chloride does not contain crystal water, it will appear blue; if it contains crystal water, it will appear red. Therefore, if you breathe into cobalt chloride blue filter paper, the water vapor will turn the filter paper red.

2. Before the experiment, use filter paper to dry the water on the upper and lower epidermis, otherwise the experimental results will be affected. The same blade was selected for comparison, because the size of the blade will affect the experimental structure.

Experimental phenomenon: Cobalt chloride blue filter paper attached to the surface of the leaf epidermis will turn red. The lower epidermis filter paper changes color first, and the color will be darker.

Experimental conclusion: Water is emitted from the upper and lower epidermis of the leaf, and the water emitted from the lower epidermis is more than the water emitted from the upper epidermis.

Plant leaves and transpiration PPT, Part 6 content: In-class exercises

1. In the leaf epidermis, the colorless and transparent cells are the ________ of the leaf, which play a _______ role in the leaf. Half-moon shaped cells are _______. The small holes between them are _______, which are the portals for gases to enter and exit the leaf.

2. The basic path for transport of water and inorganic salts in plants is ( ).

A. Sieve tubes in leaves → Sieve tubes in stems → Sieve tubes in roots

B. Sieve tubes in roots → Sieve tubes in stems → Sieve tubes in leaves

C. Vessels in the root→vessels in the stem→vessels in the leaves

D. Vessels in leaves→vessels in stems→vessels in roots

3. Please participate in the discussion and answer the question "The relationship between drought and crops"

(1) In the early stages of water shortage, the stomata of the leaves of crops will automatically close, which is beneficial to weakening the __________ function of crops.

(2) Drought-tolerant crops have a series of characteristics in their morphological structure that can adapt to drought. Table 4-7 Among the four plant leaves, the one most adapted to drought environment is ( ).

4. We often find that in urban green belts, garden workers will cut off some branches and leaves in the dark, tie transplanted plants with more soil at their roots with straw ropes, plant them in flower beds, water them enough, and cover them with black sunscreen nets.

Read the above passage and answer the following questions:

(1) Use short lines to draw the measures taken by gardeners in the short article to improve the survival rate of plants.

(2) Among the above measures, ____________________ is used to weaken the transpiration effect.

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

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"Plant Leaves and Transpiration" PPT:

"Plant Leaves and Transpiration" PPT Part One Content: Leaf Structure Leaf Structure Leaf Petiole: It is the channel through which the stem transports water and inorganic salts to the leaf. Leaf structure Upper and lower epidermis Epidermal cells: colorless and transparent, irregularly shaped Cells: in half-moon shape..

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Update Time: 2024-07-07

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

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