Unit 3 Green Plants in the Biosphere

Chapter 1 What green plants are there in the biosphere?

There are more than half a million kinds of green plants in the biosphere. It can be divided into four groups: algae, mosses, ferns and seed plants.

I. Algae, bryophytes and ferns

1, algae plants

① Living environment: Most of them live in fresh water or seawater, and some of them live in wet land.

② Structural characteristics: Algae plants have no differentiation of roots, stems, leaves and other organs.

2. Bryophytes:

① Living environment: Bryophytes mostly live in humid land environment.

② Structural characteristics: Bryophytes are generally short and have differentiation similar to that of stems and leaves, but the stems have no ducts, the leaves have no veins and the roots are very simple, so they are called pseudoroots.

③ Function: Many bryophytes have only one layer of cells in their leaves, and toxic gases such as sulfur dioxide can invade cells from the back and abdomen, thus threatening their survival. People use this characteristic of bryophytes as indicator plants to monitor the degree of air pollution.

3.ferns

① Living environment: forests and humid places in Shan Ye.

② Structural features: differentiation of roots, stems and leaves. In these organs, there is a special channel for transporting substances-transport organization.

③ Reproduction: Ferns reproduce by spores, which are a kind of germ cells.

④ Function: After a long and complicated change, the remains of ancient pteridophytes gradually turned into coal.

Second, seed plants.

1, seed structure: The seed surface has a seed coat, which can protect the tender embryo inside. Embryo is the larva of a new plant, which consists of embryo, hypocotyl, radicle and cotyledon.

① Bean seeds (P8 1 Figure 3- 10): seed coat and embryo (embryo, hypocotyl, radicle, cotyledon [2 pieces]).

② Corn seeds (P8 1 Figure 3- 10): pericarp and seed coat, embryo (embryo, hypocotyl, radicle, cotyledon [1 piece]) and endosperm.

2. Seed plants: Plants that can bear seeds are called seed plants. Seed plants include two categories: gymnosperms and angiosperms.

(1) Offspring plants: The seeds of Pinus tabulaeformis, Platycladus orientalis and Cycas are exposed, which are called offsprings.

(2) Angiosperms: peas, lychees, and papaya can only see the seeds when the fruits are pulled open. Like this, plants whose skins are outside the seeds are called angiosperms. Angiosperms are the most widely distributed family of plants on land.

3. Seed plants are more adaptable to land life than mosses and ferns. One of the important reasons is that they can produce seeds.

4. Remember the common plants and angiosperms (pages 84-85).

Chapter II Life of Angiosperms

I. Germination of seeds

1, conditions of seed germination: environmental conditions: suitable temperature, certain moisture and sufficient air; Self-condition: There are complete and energetic embryos, and they have passed the dormancy period.

2. The process of seed germination: absorbing water → transporting nutrition → radicle developing into root → hypocotyl elongation → embryo developing into bud → bud developing into stem and leaf.

3. Sampling inspection: Sampling inspection refers to taking a small number of individuals from the inspection object as samples for inspection. A method to reflect the whole situation with the test results of samples.

Second, the growth of plants.

1. Root tip structure: root cap (protection), meristem (division and proliferation), elongation (fastest elongation), maturity (root hair outside, vessel inside).

2. On the one hand, the growth of young roots depends on the division of meristem cells to increase the number of cells; On the other hand, it depends on the increase of cell volume in the elongation zone.

3. Branches are developed from buds. The buds of plants can be divided into terminal buds and lateral buds. The young leaves in the bud develop into leaves, the bud axis develops into stems, and the bud primordium develops into buds.

4. Plants need nutrition: water, inorganic salts (inorganic salts containing nitrogen, phosphorus and potassium are the most needed) and organic matter.

Third, blossom and bear fruit.

1, flower structure: (P. 104)

2. The main structures of flowers are stamens and pistils. There are pollen in the stamen anther, sperm in the pollen, ovule in the lower ovary of pistil, and egg cells in the ovule.

3. Pollination: The process of pollen scattering from anthers and falling on pistil stigma is called pollination. There are usually two pollination methods: self-pollination and cross-pollination.

4. Fertilization: The process that the egg cells in the ovule combine with the sperm in the pollen tube to form a fertilized egg is called fertilization.

5. Formation of fruits and seeds: ovary → fruit; Ovary wall → pericarp; Ovule → seed; Fertilized egg → embryo

Chapter III Water Cycle of Green Plants and Biosphere

1. water absorption: plants mainly absorb water through the root system, and the main part of root system absorbs water is the mature area of root tip.

2. Water transport: The water transport structure in the stem is the conduit. In addition to stems, there are also conduits in roots and veins, which are connected with each other to form a water pipe network.

3. Function of the catheter: The catheter can transport both water and inorganic salts.

4. The concept of transpiration: The process of water loss from the surface of living plants to the atmosphere in the form of water vapor is called transpiration. Transpiration is mainly carried out through leaves.

5. Leaf structure: Leaves are composed of epidermis (upper epidermis and lower epidermis), mesophyll and veins.

6. Stomata are the "gateway" of plant transpiration and the "window" of gas exchange. It is a cavity surrounded by a pair of half-moon cells-guard cells. Air holes can be opened and closed.

7. The significance of transpiration: ① Stimulate the transport of water and inorganic salts in the body; (2) It can reduce the surface temperature of the leaves and prevent the plants from being burned due to excessive temperature; ③ Increase atmospheric humidity and precipitation.

Chapter IV Green plants are producers of organic matter in the biosphere.

1, experiment of green leaves making organic matter under light (P. 1 17)

2. Starch is the product of photosynthesis. Light is an indispensable condition for green plants to produce organic matter.

3. Chloroplast is not only a "workshop" for producing organic matter, but also an "energy converter" for converting light energy into chemical energy.

Except water and a small amount of inorganic salts, the composition of plants is mainly organic matter. Organic matter provides energy for plant cells, and participates in the construction of plant cells, and then constitutes various tissues and organs, until the whole plant.

Green plants not only provide materials for other living things to build themselves, but also provide energy for other living things.

Chapter V Carbon and Oxygen Balance between Green Plants and Biosphere

Photosynthesis absorbs carbon dioxide and releases oxygen.

1, the process of photosynthesis:

2. The concept of photosynthesis: Photosynthesis is essentially a process in which green plants use light energy to convert carbon dioxide and water into energy-storing organic matter (such as starch) and release oxygen.

3. The application of photosynthesis principle in agricultural production: ① Conditions to ensure effective photosynthesis of crops, especially illumination. (2) Reasonable close planting, so that the leaves of crops can fully receive light.

Second, the breathing of green plants.

1, the process of breathing:

2. The concept of respiration: cells use oxygen to decompose organic matter into carbon dioxide and water, and release energy stored in organic matter to meet the needs of life activities. This process is called breathing.

3. Application of the principle of respiration in production and life: ① Loosening the soil in time in farmland and draining it in time in case of waterlogging can make the roots of plants get enough oxygen to ensure the normal respiration. (2) When storing grain, keep it dry and low temperature; When storing fruits and vegetables, lowering the temperature or oxygen concentration can inhibit respiration and prolong the storage time of food.

4. Breathing is a common feature of living things, and its essence is the decomposition of organic matter and the release of energy. Any living cell is constantly breathing, and once breathing stops, it means the end of life.

5. The role of green plants in maintaining the balance of carbon and oxygen in the biosphere: Through photosynthesis, green plants can continuously consume carbon dioxide in the atmosphere and discharge oxygen into the atmosphere, which plays an important role in maintaining the relative balance of carbon dioxide and oxygen in the biosphere.

Summary of biological knowledge points in the first volume of the seventh grade of junior high school

1, adjust the object image

Microscope use process (methods that should be paid attention to in each process)

① Take and place the mirror: hold the mirror arm with one hand and the mirror base with the other hand, and place the microscope at a distance of 10cm from the edge of the test bench.

(2) aiming: rotate the converter so that the low-power objective lens faces the light hole. Use a flat mirror when the light is strong, and use a concave mirror when the light is weak.

(3) Placement and loading: Place the glass slide specimen on the objective table, and press it with a tabletting clamp to make the specimen face the center of the light hole.

④ Adjust the focal length: turn the coarse focusing screw to make the lens barrel slowly descend until it approaches the specimen of the glass slide, and be careful that the objective lens does not touch the specimen (be sure to look at the objective lens at this time). The left eye looks at the objective lens, and at the same time, the coarse focusing screw is rotated reversely, so that the lens barrel rises slowly until the object image is seen clearly. Turn the fine focus screw slightly to make the image of the object clearer.

2. Structure and function of animal and plant cells

Vacuole, nucleus, mitochondria, cytoplasm, cell membrane, cell wall, chloroplast (marked ※ is unique to plants).

Cell nucleus: contains genetic material and can transmit genetic information.

Cytoplasm: it is not static, but constantly flowing, and its flow can accelerate the material exchange between cells and the external environment.

Chloroplast: It can synthesize inorganic substances into organic substances and realize the transformation of substances.

Cell wall: It has the function of protecting and supporting cells.

Cell membrane: it can control the entry and exit of substances, so that useful substances can not seep out of cells at will, and harmful substances can not easily enter cells.

Mitochondria: It can provide energy for the life activities of cells.

3. Functions of six organs of plants

Root: It has the functions of fixation, support, storage and reproduction, and the most important thing is to absorb water and inorganic salts.

Stem: support, storage, nutrition, reproduction, water and inorganic salts and organic matter.

Leaves: accept sunlight for photosynthesis to make organic matter.

Flowers: pollination and fertilization, fruitful development.

Fruit: Protect seeds and store nutrients.

Seed: It is a tool for plants to pass on their generations and develop into new plant larvae.

Summary of biological knowledge points in the first volume of the seventh grade of junior high school

What are the green plants in the biosphere?

1. The green plants in the biosphere include algae, bryophytes, ferns and seed plants, among which the first three plants will produce a germ cell called spore when they grow to a certain period. Because it is propagated by spores, it is also called spore plants (seedless plants).

2. Most algae plants live in water (such as fresh water: Spirogyra, Chlamydomonas seawater: laver, kelp).

(1) Morphological structure: Roots, stems and leaves are undifferentiated.

(2) Nutritional mode: All algae cells contain chlorophyll for photosynthesis, and the nutritional mode is autotrophic.

(3) Breeding mode: Breeding with spores.

3. The role of algae in the biosphere:

(1) An important source of oxygen in the biosphere.

(2) Food sources of aquatic organisms. (e.g. bait)

3 for food. (such as kelp and seaweed)

(4) medicinal.

4. Most bryophytes live in humid land environment (Cucurbitaceae, liverworts, trunk moss).

(1) Morphological structure: generally short, with differentiation similar to stem and leaf, but the stem has no vessel and the leaves have no veins. Roots are very simple, called false roots (only used to fix plants).

(2) Nutrition: Bryophyte cells all contain chlorophyll, which can be used for photosynthesis.

(3) Reproduction mode: Spores (germ cells) are used for reproduction. Bryophytes are indicator plants for monitoring the degree of air pollution.

5. Most ferns live in humid environment (such as Li Bai, Guanzhong and Manjianghong).

Morphological structure of (1): there are differentiation of roots, stems and leaves, and there are special channels for transporting substances-transport tissues in these organs.

(2) Nutritional mode: Pteridophyte cells all contain chlorophyll for photosynthesis, and the nutritional mode is autotrophic.

(3) Reproduction mode: Spores (germ cells) are used for reproduction.

The relationship between pteridophyte and human and its role in biosphere;

(1) Edible, such as bracken.

(2) It can be used as medicine, such as Selaginella and Osmunda japonica.

(3) As green manure and feed, such as Manjianghong.

(4) The source of coal.

6. Classification of seed plants: According to the number of cotyledons:

(1) Dicotyledonous plant: A plant with two cotyledons (vein network) in its embryo, in which nutrients are stored. Such as broad beans, soybeans and peanuts.

(2) Monocotyledon: A plant that has a cotyledon (with curved veins) in its embryo, and most nutrients are stored in the endosperm. Such as rice, wheat and sorghum.

7, the structure of the seed:

(1) Seed coat: protective effect.

(2) Embryo (including embryo, hypocotyl, radicle and cotyledon) is the larva of new plants, which can develop into plants in the future.

(3) Only monocotyledons have endosperm. Nutrients stored in cotyledons and endosperm are the source of nutrients when embryos develop into seedlings.

8. Comparison between seeds and spores: Seeds are rich in nutrition and have structural characteristics that adapt to the environment. If the environment is too dry or cold, you can sleep. Spore is just a cell, which can germinate only if it is dispersed in a warm and humid environment.

9. Classification of seed plants: According to the fruitless bags outside the seeds, it can be divided into ① progeny plants (such as pine, ginkgo, cycad, yew, Metasequoia glyptostroboides, Sabina vulgaris and Platycladus orientalis) and ② angiosperms.

10, angiosperms become the most widely distributed plants on the earth: angiosperms generally have very developed transport organizations, thus ensuring efficient transport of water and nutrients in the body; They can generally blossom and bear fruit, and fruits can protect the seeds inside, and many fruits can also help the seeds spread.