"Photosynthesis absorbs carbon dioxide and releases oxygen" Carbon-oxygen balance in green plants and biosphere PPT courseware 7

Description

"Photosynthesis absorbs carbon dioxide and releases oxygen" Carbon-oxygen balance in green plants and biosphere PPT courseware 7

learning target

1. Knowledge and skills:

1. What are the raw materials and products of photosynthesis?

2. What is the concept of photosynthesis?

3. How is the principle of photosynthesis applied to agricultural production?

2. Teaching focus:

The formula of photosynthesis: what are the raw materials, conditions, and products.

3. Teaching difficulties: the process of exploring experiments.

1. Priestley’s classic experiment in 1773

1. Photosynthesis uses carbon dioxide as raw material P122

Priestley concluded that plants could renew the air that had become polluted by the burning of candles or the respiration of animals.

Scientific experiments have proven that: candle burning and animal respiration will emit carbon dioxide and consume oxygen, while photosynthesis of plants can release oxygen and consume carbon dioxide. In addition to water, carbon dioxide is the raw material for photosynthesis of green plants.

Is carbon dioxide a necessary raw material for photosynthesis?

Ask the question: Is carbon dioxide a raw material for photosynthesis?

Make a hypothesis: Carbon dioxide is the raw material for photosynthesis.

Make a plan: Materials and tools:

Two glass dishes, two jars, two beakers, two branches with leaves, sodium hydroxide solution, water

Experimental tip: Sodium hydroxide solution has the effect of absorbing carbon dioxide in the air. (You can use a little 25% sodium hydroxide solution to absorb the carbon dioxide in the air) Note: Sodium hydroxide solution is corrosive, so do not let your skin come into contact with it.

group discussion:

①What should be chosen as the variable for this experiment?

②In addition to this variable, what should be the other conditions?

③How to design a control group?

Implementation Plan:

1. Fill Petri dish A with clean water and Petri dish B with sodium hydroxide solution.

2. Place them in a dark place at the same time for a day and night, and then move them to the light together.

3. After a few hours, take a leaf from each device A and B, number it A and B respectively, then put it in alcohol and heat it over water to remove the chlorophyll, and then wash it with clean water.

4. Put two drops of iodine solution on each leaf of A and B and observe.

2. Photosynthesis can also produce oxygen

Pay attention and observe

1. Did the hornwort in the experimental device release bubbles?

2. Will the sanitary incense that is about to go out in the experimental device re-ignite after being put into the mouth of the pipe?

The sanitary incense that was about to go out burned again when it encountered the gas produced by hornwort, indicating that the gas released was oxygen.

Experimental conclusion: Photosynthesis also produces oxygen

3. The process of photosynthesis

1. Concept: Green plants use light energy through chloroplasts to convert carbon dioxide and water into organic matter that stores energy (such as starch) and release oxygen.

2. The expression of photosynthesis:

Carbon dioxide + water--organic matter + oxygen

3. The essence of photosynthesis:

①. Material transformation: convert carbon dioxide and water into organic matter and oxygen

②. Energy conversion: convert light energy into chemical energy

4. Application of photosynthesis in agricultural production

Compare the three planting methods to see the differences in their growth conditions and analyze the reasons (from the perspective of photosynthesis utilization).

Planting too thinly: not making full use of light and causing waste;

Reasonable dense planting: make full use of light and increase yields

Planting too densely: The leaves block each other and affect the photosynthesis of the plant.

The method of applying carbon dioxide to crops in fields and greenhouses to increase crop yields is called air fertilizer, and carbon dioxide is called "aerial fertilizer."

Specific operation methods

1. Directly spray carbon dioxide stored in the cylinder

2. Light the briquette stove.

practice

1. During photosynthesis, the external conditions that plants do not need are ( )

A.Carbon dioxide B. water

C. High temperature D. Light

2. The essence of plant photosynthesis is ( )

A. Synthesize organic matter and release energy B. Synthesize organic matter and store energy

C. Decompose organic matter and store energy D. Decompose organic matter and release energy

3. The raw materials for photosynthesis are ( )

A.Light and water B.Water and carbon dioxide

C.Chloroplasts and light D.Oxygen and water

Textbook exercises

1. Judgment

(1) The raw materials for photosynthesis are water and carbon dioxide. ( )

(2) Every cell in a plant can perform photosynthesis. ( )

(3) The essence of photosynthesis is to create organic matter, release oxygen, and release all the energy in the organic matter. ( )

(4) Reasonable and dense planting can ensure that the leaves of the crops can fully receive light without blocking each other. ( )

2. Please summarize the raw materials, conditions, locations and products of photosynthesis in an appropriate form.

Raw materials: water, carbon dioxide; conditions: light energy; location: chloroplasts;

Products: oxygen, organic matter.

3. The picture on textbook P126 shows an instrument used to increase carbon dioxide concentration in a greenhouse on a farm. What is the purpose of installing this instrument in the greenhouse? What's the principle?

Purpose: Increase carbon dioxide concentration, promote photosynthesis, and increase crop yields.

Principle: Increase reactants, promote photosynthesis of green plants, and increase products.

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For more information about the PPT courseware "Carbon-Oxygen Balance in Green Plants and the Biosphere, Photosynthesis Absorbs Carbon Dioxide and Releases Oxygen", please click the Carbon-Oxygen Balance in Green Plants and the Biosphere PPT Photosynthesis Absorbs Carbon Dioxide and Releases Oxygen PPT tag.

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Update Time: 2024-07-08

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

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