Junior high school biology

The biological world (Part 7, P3-P15)

1. Classification of living things

▲Classification according to morphological structure : Divided into animals, plants, bacteria, fungi, viruses and other organisms

2. Characteristics of living things: (1) Made of cells (except viruses) (2) Living things can grow and develop

(3) All living things have metabolism (4) All living things have reproduction, inheritance, and mutation phenomena

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(5) Organisms can respond to external stimuli (6) Organisms can adapt to a certain environment and can also affect the environment

▲In an experiment to explore the impact of light on the lives of rat women:

① The variable of the experiment is light, and other conditions should be the same.

② The reason why 10 rats were used in the experiment instead of 1 was to reduce the chance of the experiment and improve the reliability of the experiment.

▲The process of inquiry: 1. Ask questions → 2. Make assumptions → 3. Make plans and implement plans → 4. Draw conclusions → 5. Express and communicate

▲Contrast In the experiment, the control group and the experimental group should have the same conditions except for the experimental variables that need to be controlled. That is, the variable is unique.

Exploring life (Part 7, P17-P28)

1. Microscope:

▲The observed image is an inverted image that is opposite to the actual image. Note that the slide moves in the opposite direction to the object in the field of view.

▲Magnification = objective lens magnification × eyepiece magnification

▲Biological specimens observed under a microscope should be thin and transparent, allowing light to pass through so that they can be observed clearly. Therefore, it must be processed into glass slide specimens.

▲Use of microscope:

(1) Pick up and place the lens: Hold it with the left hand and hold it with the right hand

(2) Aiming the light: ①Choose a low-power objective lens Quasi-clear aperture (the objective lens is 2cm away from the stage)

②Select a larger aperture and align it with the clear aperture, and finally see a bright white field of view in the microscope

③Observe with the left eye, Record with the right eye and align the light reflected by the reflector with the light aperture

(3) Observation: When the objective lens drops significantly, your eyes should watch the lens drop from the side

(4) Organize

2. Preparation of temporary slide specimens:

▲The man known internationally as the "Father of Hybrid Rice" (Yuan Longping)

▲When observing the mounted slides with a microscope, it was found that there were If a stain does not move even when moving the objective lens or slide specimen, it means that the stain is in the (eyepiece)

▲When you find that the microscope lens is not clean, the correct way to remove the stain is (wipe it with lens cleaning paper) )

▲Write a small letter "d" on the slide and observe it with a microscope, you will see that the shape of the enlarged image is (p)

3. In order to explore "the impact of light on the life of rat women", Xiaodong conducted the following experiment: (5 points)

① Make a rectangular carton from cardboard (without a lid on the top), and put the carton Divide it into two parts of equal length, wrap one part in black paper to create a dark environment, and leave the other part untreated.

②Put the carton on the table and put the 10 captured rat women into the center of the carton.

③Observe the mouse woman’s movements after 10 minutes: How much should she move to the dark end? Or should it be moved to the brighter end?

Please analyze and answer the following questions:

(1) Xiaodong wrapped one end of the carton in black paper to create a dark environment, and left the other end untreated for __________.

(2) When Xiaodong was doing the experiment, Xiaoming was also there and suggested to Xiaodong that he should sprinkle some water on the dark end of the carton to make it moist, while the bright end should be kept dry. But Xiaodong did not adopt Xiaoming's suggestion. Do you think Xiaodong did the right thing? __________;Why? __________________________________________________.

(3) What should be done with the rat wife after the experiment? ____________________________.

Structural levels of organisms (Part 7, P30-P52)

1. Cell - the basic unit of life activities of organisms (except viruses)

▲ The basic structure of plant cells includes cell wall, cell membrane, cytoplasm and nucleus. In the cytoplasm there are vacuoles, chloroplasts and mitochondria.

▲The basic structure of animal (human) cells includes cell membrane, cytoplasm and nucleus.

▲The structural differences between plant cells and animal (human) cells: Plant cells have more cell walls, vacuoles, and chloroplasts than animal cells.

▲The role of each cell structure: =

(1) The cell wall in the plant cell structure is located on the outer layer of the plant cell and has the function of protecting the internal structure of the cell and maintaining the cell shape (supporting ) function. It allows plant cells to absorb water without bursting.

(2) The cell membrane has the function of protecting the internal structure of the cell, and it can also control the entry and exit of substances inside and outside the cell (gatekeeper).

Not easy to see under a microscope.

(3) Cytoplasm is a transparent liquid with fluidity, which is conducive to the exchange of materials between cells and between cells and the external environment. It is an important place for life activities.

(4) The presence of mitochondria in the cell cytoplasm is related to cellular respiration (power workshop); the chloroplasts of plant cells are related to plant photosynthesis (production workshop); the vacuoles of plant cells are filled with cell fluid (outflow from cut melons and fruits) The juice is usually cellular fluid). Mitochondria and chloroplasts are both energy converters.

(5) The nucleus contains genetic material and transmits genetic information (management and regulation department).

▲There is a substance in the cell nucleus that is stained darkly with an alkaline dye called a chromosome. Its main components are deoxyribonucleic acid (DNA) and protein. Among them, deoxyribonucleic acid (DNA) is the main genetic material.

▲Identification of chromosome diagram:

▲Identification of cell diagram:

▲Observation experiment of cells:

(1) Observation When looking at onion epidermal cells, it was found that the most deeply stained part of the cells was the nucleus; the shape of onion epidermal cells was a long grid-like cuboid.

(2) When observing human oral epithelial cells, it was found that the most deeply stained part of the cells is the nucleus; the shape of oral epithelial cells is flat cells with neat edges. The site where epithelial cells are scraped is the inner wall of the oral cavity; the liquid dropped in the center of the slide is 0.9% normal saline, which is used to maintain the original shape of the cells.

2. Cell life

▲The result of cell division is an increase in the number of cells; the result of cell growth is an increase in cell volume. Organisms grow from small to large (growth) as a result of cell division and cell differentiation.

▲Cell division is usually the process of one cell dividing into two cells. First of all, the cell nucleus divides, and chromosomes appear inside it. The chromosomes are evenly divided into two parts in the center and move to both ends of the cell. Secondly, the cytoplasm is also divided into two parts equally. Finally, the cell membrane (wall) is formed. The chromosomes of the new cell produced by division are identical to those of the original cell.

▲Cell differentiation refers to the process in which cells after division change in shape, structure and function in different directions. The result of cell differentiation is the formation of tissues.

3. Tissue refers to a group of cells with similar morphology, structure and function.

(1) The main tissues of plants include: meristematic tissue, basic tissue, protective tissue and conductive tissue.

Tissue name, function, example

Meristematic tissue has the ability to divide and proliferate, such as: root tips, buds

Basic tissue, can produce and store organic nutrients, such as: pulp

Protective tissue, protective function, such as: plant epidermis

Conducting tissue, transporting water, inorganic salts, and organic nutrients, such as: vessels and sieve tubes in leaf veins

( 2) The main tissues of the human body include epithelial tissue, muscle tissue, connective tissue and nervous tissue.

Tissue name, function, part composition

Epithelial tissue, protective effect, outer surface of skin, inner surface of organs and intestines and stomach

Muscle tissue, contraction and relaxation, causing body movement, bones Muscle, cardiac muscle, smooth muscle

Connective tissue supports, nourishes, connects and protects blood, bone tissue, fat, tendon

Nervous tissue can produce excitement and conduct excitement when stimulated Brain and spinal cord

(3) The formation of tissue is the result of cell differentiation. Schematic diagram of tissue formation:

4. Organs refer to structures composed of several different tissues that perform certain functions in the organism.

▲A complete green flowering plant includes six organs: roots, stems, leaves, flowers, fruits and seeds. Among them, roots, stems, and leaves are vegetative organs, and flowers, fruits, and seeds are vegetative organs.

▲The chest cavity of the human body contains organs such as the heart and lungs, and the abdominal cavity contains organs such as the stomach, intestines, and liver. A bone or muscle is an organ.

5. System refers to the further orderly connection of some organs to complete one or several biological activities at the same time, forming a system. The major systems of the human body mainly complete various life activities simultaneously under the regulation of the nervous system and endocrine system.

6. The composition of living organisms

▲The structural hierarchy of multicellular plants is: cells → tissues → organs → plants.

▲The structural hierarchy of multicellular animal bodies is: cells → tissues → organs → → systems → animal bodies.

▲Characteristics of morphological structure and life activities of single-cell organisms: (1) The body is composed of only one cell. (2) Ability to independently complete nutrition, respiration, excretion, exercise, reproduction and other life activities.

▲Single-celled organisms: (1) All bacteria (2) Plants - Chlamydomonas, diatoms (3) Animals - Paramecium, Amoeba (4) Fungi - Yeast

7. Paramecium

▲Shape: Like an inverted straw sole.

▲Structure: surface membrane, cytoplasm and nucleus, food vacuole, telescopic vacuole.

▲Life activities: movement - cilia swing; nutrition - food is bacteria, single-cell algae, digested and absorbed in food bubbles; excretion - telescopic vesicles, surface membrane; respiration - surface membrane; Reproduction - cell division.

▲Why is it said that Paramecia can purify sewage? Answer: Consume the organic matter in the water and swallow the bacteria.

▲Compared with plant cells, Paramecium has no cell wall, chloroplasts and vacuoles. There are no chloroplasts in the cells and cannot produce organic matter by itself.

▲Put two drops of Paramecium culture fluid on the glass slide, connect them in the middle, and add salt to one side. All Paramecium will swim to the side without salt, because Paramecium can escape harmful stimuli. ; If you add beef soup on one side, all the paramecium will be concentrated in the beef soup, because the paramecium can tend to be beneficial stimulation.

▲Paramecium memory chart

8. The general process of inquiry experiments: raising inquiry questions; making hypotheses; designing inquiry experiments; analyzing experimental phenomena and drawing conclusions; expressing and communicating.

▲Case: Explore "Where do the maggots in carrion in summer come from?"

(1) Ask the question: Where do the maggots in carrion in summer come from?

(2) Make a hypothesis: Maggots are (or are not) transformed from rotten meat.

(3) Design and implement an exploratory experiment: Place two pieces of fresh meat of the same size in two wide-mouth bottles A and B respectively. Among them, A's wide-mouth bottle is not sealed, while B's is sealed with multiple layers of gauze.

(4) Analyze the experimental phenomena and draw conclusions:

▲Experimental phenomena: After a few days, the meat in bottles A and B rotted; maggots were found on the rotten meat in bottle A ( fly larvae), there were no maggots in bottle B sealed with gauze.

▲The explanation for the appearance of maggots on the carrion of bottle A is: the jar was not sealed, and flies from the outside came into contact with the carrion.

▲The conclusion you draw from this experiment is that maggots do not come from rotting meat.

In a controlled experiment, the experimental group and the control group should have the same experimental conditions except for setting a certain variable.

Seeds (Part 7, P55-P58)

1. Structure of seeds

We commonly see many seeds, such as corn. Seeds of wheat, peanuts, soybeans, beans, etc. The size and shape of seeds vary widely, but their basic structure is the same, which is composed of seed coat and embryo. The embryo is actually a young living body, that is, the larvae of a new plant body, and is the main part of the seed. It includes Cotyledons, embryo, hypocotyl and radicle. Some seeds also have endosperm.

2. Comparison of the structure of kidney bean seeds and corn seeds: ▲The structure of kidney bean seeds

▲The structure diagram of kidney bean seeds▲The structure diagram of corn seeds

▲Corn seeds Structure

▲Similarities and differences between the structures of bean seeds and corn seeds

Similarities Differences

Bean seeds have seed coat and embryo but no endosperm. Nutrients are stored in the cotyledons, which have two cotyledons

Corn seeds have a seed coat and an embryo, and have an endosperm. Nutrients are stored in the endosperm, and there are one cotyledon.

All seeds have two embryos. Leaves are called dicotyledonous plants, such as beans, peanuts, watermelons, peach trees, etc.

Any seed whose embryo has one cotyledon is called a monocot, such as corn, wheat, sorghum, rice, etc.

3． Germination of seeds

▲External environmental conditions for seed germination: suitable temperature, certain moisture, and sufficient air

Internal conditions: embryos with complete and vitality have passed through dormant period.

▲The process of seed germination: water absorption - nutrient transport - radicle develops into root - embryonic axis develops into stem and leaves. The first thing to break through the seed coat is the radicle. The fat, white part of edible bean sprouts develops from the hypocotyl.

▲Cooked seeds do not germinate because the embryo has no vitality; rice sown in the field does not germinate because the embryo is incomplete; dry seeds do not germinate because there is not enough moisture; seeds that are completely immersed in water do not germinate. Germination occurs because there is insufficient air; farmers cover the ground with plastic film in early spring to allow early emergence because it provides a suitable temperature for seed germination.

▲ To determine the germination rate of a bag of seeds, the method that should be used is sampling testing. Only when the germination rate exceeds 90℅ can the seeds be given to farmers.

▲ The flour we eat comes from the endosperm of wheat seeds; peanut oil comes from the cotyledons of peanut seeds. So the nutrients of seeds are stored in the cotyledons or endosperm.

Root (Part 7, P60-P67)

1. The structure of the root tip

▲ The main function of the root is to absorb water and inorganic salts from the soil. The structure of the root tip includes root cap, meristematic zone, elongation zone, and mature zone in order from the tip upward.

▲ Structural diagram of the root tip: ▲ Characteristics of each structure of the root tip:

▲ The most critical part of root growth is the meristematic zone; the fastest part of root growth is elongation area; when transplanting seedlings, soil should be used to protect the young roots and root hairs.

2． Functions of roots

▲ Water absorption by roots:

(1) The main part of roots that absorb water is the mature area of ??the root tip. Observe this area with the naked eye and find that there are a large number of white "fuzz", which are root hairs. The significance of the large number of root hairs appearing in the mature area is to increase the absorption area.

(2) Plants need water for their lives because: ① Water is the main component of plant cells; ② Water can maintain the posture of plants, such as plants being stiff and leaves stretching; ③ Water is involved in many aspects of plant life Activities such as photosynthesis, respiration.

(3) The condition for roots to absorb water is that the concentration of cell fluid in root cells is greater than the concentration of soil solution. Applying too much fertilizer at one time will cause "seedling burning" because the concentration of the soil solution is greater than the concentration of the root cell solution. When tomatoes are mixed with sugar, the cells will lose water; when wilted vegetables are placed in clear water, the vegetables will absorb water and become stiff; plants on saline-alkali soil do not grow well because the soil solution concentration is greater than the root cell solution concentration, and the roots cannot absorb water.

(4) There are barren lands and oases in the desert, which shows that water can affect the distribution of plants.

▲Pictures of plant cells "absorbing water" and "losing water":

▲The picture on the right is a set of experiments designed by a classmate: dig out one of two radishes of similar size each For equal holes, pour equal amounts of clean water and concentrated salt water into the holes of radish A and B respectively, plug the holes with a rubber stopper with a glass tube in each, and record the height of the liquid level in the glass tube (as shown in the picture). Leave it for a period of time and analyze the changes that will occur:

(1) The change in the height of the liquid level in the glass tube is that the level of liquid A drops; the level of liquid B rises_.

(2) The feeling of pinching a radish with your hands: A is hard; B is soft.

(3) Conclusion Plant cells can absorb or lose water.

(4) The water absorption or loss of plant cells mainly depends on the concentration of the cell fluid and the concentration of the external solution.

(5) This can explain: why you cannot apply too much fertilizer to crops at one time

The concentration of the soil solution will be greater than the concentration of the root cell solution, and the plant will not be able to absorb water and die.

▲ Absorption of inorganic salts by roots:

(1) The three inorganic salts that plants require the most for growth are nitrogen, phosphorus, and potassium.

(2) Table of effects of three inorganic salts:

Stem (Part 7, P68-P71)

1. Bud

▲A bud is an unexpanded branch or flower. The buds that will develop into flowers in the future are called flower buds;

The buds that will develop into branches in the future are called branch buds. Branches (branches) are composed of stems, leaves, and buds.

▲Branch and bud diagram:

2. Stem structure:

▲The stem of woody plants consists of bark, cambium, There are four parts: xylem and pith.

▲ There is no cambium layer in the stems of herbaceous plants, so the stems cannot become thicker year by year.

▲ Wood is mainly made from the xylem of woody plant stems; hemp fiber used for weaving clothes is mainly made from the phloem of woody plant stems.

3. The functions of stems:

Flowers and fruits (Part 7, P73-P75)

1. Flower structure:

▲Flower structure diagram

▲ The opening of flowers is affected by many factors, such as light, temperature, humidity, etc. "The beauty of the world ends in April, and the peach blossoms in the mountain temple begin to bloom." (Temperature)

▲ The main parts of a flower are stamens and pistils, because they are related to the formation of fruits and seeds.

2． Fruit structure:

▲ Fruit consists of two parts: peel and seeds.

▲ A peanut is a fruit; "Peanut rice" is the seed of peanut; "Ma Wuwu" refers to the peel of peanut; "Red Tent" refers to the seed coat of peanut; "White Fatty" refers to peanut seeds of embryo.

▲ Common fruits include wheat kernels, corn kernels, watermelon, grapes, and cucumbers. Common seeds include broad beans, mung beans, watermelon seeds, almonds, and sesame seeds.

▲ After flowering, pollination, and fertilization of green flowering plants, the flower petals, pistil stigmas, styles, and stamens also slowly wither. Only the ovary

grows gradually, and the ovules in the ovary also develop slowly. Final:

Photosynthesis and respiration (Part 7, P77-P96)

1. Photosynthesis

▲ The concept of photosynthesis: the process in which green plants use light energy through chloroplasts to convert carbon dioxide and water into organic matter that stores energy and releases oxygen.

▲ The formula of photosynthesis:

2

▲ The main organ of photosynthesis is the leaf; the place of photosynthesis is the chloroplast; the condition of photosynthesis is light (Why does photosynthesis require light? Light provides energy or power for photosynthesis.)

▲ The raw materials of photosynthesis are carbon dioxide and water; the products of photosynthesis are organic matter and oxygen.

▲The essence of photosynthesis: synthesis of organic matter (carbon dioxide and water converted into organic matter)

Storage of energy (conversion of light energy into chemical energy that can be stored, such as petroleum and coal)

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▲ The significance of photosynthesis: ① Provides a source of food (organic matter) for almost all organisms; ② Provides a source of oxygen for almost all organisms, balancing the contents of oxygen and carbon dioxide; ③ Provides a source of food (organic matter) for almost all organisms source of energy.

▲ Application of photosynthesis: Factors that affect the efficiency of photosynthesis include light, temperature, humidity, carbon dioxide concentration, etc.

Methods to increase yield: ① When the concentration of carbon dioxide in the air is increased to 0.5℅~0.6℅, the photosynthesis of crops will be significantly enhanced. Carbon dioxide is the main raw material for photosynthesis and is also known as "aerial fertilizer." ② Increase the temperature appropriately. For example, use greenhouses to produce off-season vegetables. ③The reason for pruning fruit trees to increase production is to concentrate organic matter into strong fruits. ④Plant reasonably densely. ⑤ Increase the lighting time and intensity appropriately.

▲ Photosynthesis experiment:

(1) Verification: Green leaves produce starch under light

① Dark treatment: Put the geranium in a dark place for a day and night. Purpose: Let geraniums transport and consume all the starch in their leaves in the dark.

② Control experiment: Cover the upper and lower sides of half of a leaf with black paper. Purpose: To conduct a control experiment to see whether the part is illuminated or not

(2) Verification : Green leaves produce oxygen under light

① Take hornwort and put it in a beaker filled with water, and then turn back a funnel. A test tube filled with clean water is fastened to the neck of the funnel.

② Move the device to the sun, and soon you will see that the hornwort is constantly releasing small bubbles.

③ After some gas is collected in the test tube, press the mouth of the test tube and take out the test tube.

④ Loosen the mouth of the test tube and quickly insert the thin wooden strips with sparks into the test tube. What you will see is that the thin wooden strips with sparks re-ignite.

Conclusion: Oxygen can support combustion. Green leaves produce oxygen when exposed to light.

(3) Verification: Green leaves absorb carbon dioxide under light

2. Respiration

▲The concept of respiration: cells use oxygen to decompose organic matter into Carbon dioxide and water, and release the energy stored in organic matter to supply the processes required for life activities.

▲The formula of respiration:

▲The essence of respiration: decompose organic matter; release energy.

▲ The significance of respiration: providing energy for various life activities of plants. Such as (cell division, absorption of inorganic salts, transportation of organic matter)

▲ Application of respiration:

(1) Promote respiration: ① loosen soil for crop roots; ② after flooding Drain water in time.

(2) Methods to inhibit respiration: ① lower the temperature; ② reduce the oxygen supply; ③ reduce the water content of plant cells (drying).

(3) Why are Xinjiang Turpan melon fruits so sweet? Because the temperature in this place is high during the day, photosynthesis is strong, and a lot of organic matter is produced; the temperature is low at night, respiration is weak, and organic matter is decomposed. Therefore, the fruits are very sweet.

(4) How to extend the storage time of seeds, fruits and vegetables? . Low temperature and dryness reduce oxygen and inhibit respiration.

(5) Why do radishes become hollow after being stored for a long time? Will fruit become lighter and taste worse if kept for a long time? Because respiration breaks down organic matter.

▲Experiments on respiration:

(1) Verification: Respiration produces carbon dioxide

(2) Verification: Respiration absorbs oxygen

(1) Difference:

Photosynthesis Respiration

Place Cells containing chloroplasts All living cells

Conditions: Light, all the time (day and night)

Products: organic matter and oxygen, carbon dioxide and water

Raw materials: carbon dioxide and water, organic matter and oxygen

Essence Synthesize organic matter; store energy; decompose organic matter; release energy

(2) Connection: interdependence. Because the organic matter decomposed by respiration is produced by photosynthesis, the energy released by respiration is stored by photosynthesis; and the energy required for photosynthesis is released by respiration.

▲ Is it better to put plants in the bedroom during the day or at night? daytime. Because photosynthesis of plants is stronger than respiration during the day, it will add oxygen to the bedroom; while at night, plants will compete with people for oxygen due to respiration.

Leaves (Part 7, P82-P84)

(1) The structure of the leaves: generally includes three parts: epidermis, mesophyll, and veins. The main reason why leaves are green is that the chloroplasts contain green chlorophyll.

▲Structure diagram of leaves

▲Experiment: Observation of the structure of leaves

(2) Function of leaves: They are the main ones for photosynthesis and transpiration organ. The condition for the formation of chlorophyll is light. For example: leek, cabbage heart

▲Why are the leaves darker on the front and lighter on the back? Because it is close to the palisade layer of the upper epidermis, the cells are tightly arranged and contain many chloroplast particles. In the sponge layer near the lower epidermis, the cells are loosely arranged and contain few chloroplast particles. So the front is dark and the back is light.

The role of green plants in the biosphere (Part 7, P98-P111)

1. The role of green plants in the biosphere: ① Provide food for various organisms;

② Promote the oxygen cycle and maintain a relative balance between oxygen and carbon dioxide in the biosphere;

③ Promote and stabilize the water cycle.

2. The biosphere is the general term for the living things on the earth and their living environment.

3. Green plants affect the oxygen cycle through photosynthesis. Plants absorb carbon dioxide and release oxygen, keeping oxygen and carbon dioxide in relative balance in the biosphere. The volume fraction of oxygen in the biosphere is 21% and carbon dioxide is 0.03%

4. Green plants convert light energy into chemical energy through photosynthesis and store it in the organic matter of the plant body. These organic matter not only provide life for the plant itself Activities provide energy and also provide energy for the life activities of animals and humans.

5. Green plants participate in the water cycle of the biosphere through transpiration. The driving force of the water cycle is mainly light energy, which causes water to enter the atmosphere through evaporation. The plant canopy, litter, herbs, bryophytes, etc. are beneficial to soil and water conservation.

6. The top three major food crops in the world in terms of output are wheat, corn, and rice.

7. The energy we obtain from drinking milk comes directly from respiration; indirectly from photosynthesis; and finally from the sun.

▲ Transpiration

(1) Concept of transpiration: The process in which water is emitted from the plant body to the outside of the plant in a gaseous state is called transpiration. Mainly on the leaves.

(2) The significance of transpiration:

① It can lower the temperature of the plant so that the plant will not be burned

② Promote the roots to absorb water; promote water Transported within the body. Transpiration is the main driving force for plants to absorb water.

③ It can promote the transportation of inorganic salts dissolved in water in the body.

④ It can increase atmospheric humidity, lower ambient temperature, and increase precipitation. Promote and stabilize the biosphere water cycle. (Note on the external environment

▲ A very small part (1%) of the water in the mesophyll cells participates in various life activities in the plant, and the vast majority (99%) turns into water vapor and is emitted to the atmosphere through the stomata. . The opening and closing of stomata can regulate transpiration, so that the plant body always maintains appropriate moisture.

▲The parts that people eat: sweet potatoes, radish roots, cabbage, spinach, celery, leeks, etc. They are leaves, cauliflower and day lilies are flowers, lotus roots, potatoes, water chestnuts, sugar cane, etc. are stems, and cucumbers, kidney beans, apples, etc. are fruits.

▲The role of forests: providing abundant resources for humans; Participates in the oxygen cycle and water cycle through photosynthesis and transpiration; absorbs toxic gases, reduces the harm of noise and strong light to the human body, and promotes physical and mental health; it is a paradise for animals to live in.

▲my country’s forest resources: forests. The coverage rate is 18.21%, which is 61.3% of the world. March 12 is my country’s Arbor Day, and the Forest Law of the People’s Republic of China was promulgated in 1984.

▲ Common environmental protection effects. The main tree species include plane trees, pittosporum, ligustrum, locust, etc. Commonly used lawn plants include tall fescue, wood sorrel, bermudagrass, etc.

▲The following are two designs designed by students in the interest group. Both experimental devices are used to observe the transpiration of plants. Please analyze and solve the problem according to the schematic diagram:

(1) Of the two experimental devices, A and B are more reasonable and scientific.

(2) After a period of time, water droplets will appear on the plastic film

(3) In order to make the experimental phenomenon obvious, the two experimental devices should be placed in the sun.

▲ Transplanting. When growing plants, some branches and leaves are often removed to reduce water transpiration.

▲ People feel cooler in the shade of trees than in the shade of houses. The reason is ( )

A. Transpiration B. Respiration C. Photosynthesis D. Shading Sunlight

▲ The main part of a plant that performs transpiration is ( )

A. Stem B. Leaf C. Petiole D. Various parts of the plant body