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Anonymous users2024-02-13Junior Biology Experiment: Observe the structure of leaves.
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Anonymous users2024-02-12The blade structure diagram is as follows:
1. a blade. The leaf is composed of three parts: epidermis, mesophyll and vein. The essence of photosynthesis is the process of green plants using light energy through chloroplasts, synthesizing carbon dioxide and water into organic matter, and releasing oxygen.
Respiration is the process by which plants absorb oxygen, break down organic matter into carbon dioxide and water, and release the energy needed for plant growth.
2. a blade. The leaf is composed of three parts: epidermis, mesophyll and vein. The essence of photosynthesis is the process of green plants using light energy through chloroplasts, synthesizing carbon dioxide and water into organic matter, and releasing oxygen.
Respiration is the process by which plants absorb oxygen, break down organic matter into carbon dioxide and water, and release the energy needed for plant growth.
3. Supporting leaves. The leaves are born at the junction of the petiole and the stem, respectively, on both sides, and its form and function have certain differences according to different plants, for example, the leaves of peas can carry out photosynthesis, while the leaves of jujube can become thorns, and the leaves of more plants will fall off in the process of growth.
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Anonymous users2024-02-111. Experimental preparation.
Ingredients: Fava bean leaves.
Supplies: Microscope, glass slides, coverslips, blades, tweezers, Petri dishes, water, 70 degrees of alcohol.
Second, the method and steps.
1) The internal structure of the broad bean leaf Take the broad bean leaf and slice it freehand If you don't use a gripper, you can operate it according to the following method:
Cut the broad bean leaves into small narrow strips, place the narrow strips on the glass slide, press the narrow strips of the leaves with the tip of the left index finger, pinch the blade with the thumb and index finger of the right hand, and pull down against the fingertips of the left index finger, so many cuts, and choose the thinner material to observe. Under low magnification, the outermost layers of the dorsal and ventral sides of the leaf are the upper and lower epidermis, and their cells are closely arranged, and the outer surface has a transparent cuticle (the cuticle of the upper epidermis is more obvious). Adjusting the focal length of the microscope, the stomata can be seen on both the upper and lower epidermis (a cross-section of the guard cells, whose cells are slightly smaller than the epidermis) can be seen, and there are more stomata on the lower epidermis than on the upper epidermis.
Its mesophyll has distinct palisade tissue and spongy tissue. The palisade tissue adjacent to the upper epidermis is composed of one or two layers of palisade-like, long-columnar cells. (Be sure to explain the essentials of slicing to students before the experiment, mainly with the nail of the left index finger facing downwards and perpendicular to the slide as much as possible, so that not only can you cut thinly, but also avoid cutting your fingers.)
When making the coverslip, care must be taken to keep the position of the leaf cross-section unchanged. In this way, after adjusting the focal length, the fence tissue and the sponge tissue can be distinguished. ）
Palisade tissues contain a large number of chloroplasts inside their cells. If the section is thick, it is possible to lose the outline of the cell. The slices can be placed in alcohol with a volume fraction of 70, soaked for a few minutes, part of the chlorophyll in the chloroplast can be dissolved, and the color of the mesophyll will be lightened.
The spongy tissue adjacent to the lower epidermis is composed of several irregular layers of cells with large intercellular spaces to facilitate ventilation. There are fewer chloroplasts inside the cells of the spongy tissue. Colorless vascular bundles (veins) can also be observed within the mesophyll.
If the longitudinal section of the catheter is observed (because the veins are reticulated, there are often both longitudinal and horizontal sections of the catheter in the section), the ornamentation on the catheter can be seen. The xylem in the leaf vein is located above the leaf vein, while the phloem is located below the leaf vein. Because the phloem is mainly composed of parenchyma cells, it is less pronounced than the ductal morphology.
After observation with a low magnification, a high magnification can be used to observe the cross-section of the guard cells around the stomata in the leaf epidermis. The lower epidermis of dicot leaves contains more stomata than the leaves.
2) Surface observation of the epidermis of broad bean leaves.
Peel off the lower epidermis of broad bean leaves and make slices for observation. Under a low-power microscope, the edges of adjacent cells in the lower epidermis can be seen as corrugated and mosaic with each other. After observing the epidermal cells, the stomata are found.
If you look closely at the stomata with a high-powered microscope, you can see that it is composed of two half-moon-shaped cells and a stomata of **. ）
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Anonymous users2024-02-10Junior Biology Experiment: Observe the structure of leaves.
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Anonymous users2024-02-09There are many stomata on the leaf epidermis, which are surrounded by pairs of guard cells; The opening and closing of the stomata is controlled by the guard cells, and the mesophyll cells close to the upper epidermis are cylindrical and neatly arranged, some like palisades, called palisade tissues, and there are more chloroplasts in the cells; The mesophyll cells near the lower epidermis are irregularly shaped and loosely arranged, some resemble sponges, called spongy tissue, and contain fewer chloroplasts.
Mesophyll cells are composed of sponge tissue and palisade tissue, and there are two kinds of channels in the leaf veins, in which the ducts can transport water and inorganic salts, and the sieve tubes can transport organic matter from top to bottom.
Photosynthesis and transpiration of leaves are mainly carried out through leaves. The whole shape of the leaf is called the leaf shape, the top is called the leaf end or the tip of the leaf, the base is called the leaf base, the periphery is called the leaf margin, and there are many leaf veins distributed in the leaf.
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Anonymous users2024-02-08The structure of the leaf includes: epidermis, mesophyll cells, veins.
The epidermis is divided into upper epidermis and lower epidermis and is generally composed of a layer of cells. The epidermis is characterized by stomata - which are composed of two kidney-shaped guard cells. Mesophyll is the most developed and important tissue of the leaf, composed of parenchyma cells containing many chloroplasts, and in the two-sided leaves with dorsal ventral division, the mesophyll tissue is divided into barrier tissue and sponge tissue.
The veins are composed of vascular bundles and mechanical tissue. Among them, the leaf structure of monocotyledonous grasses is basically the same as that of general angiosperms. However, the epidermis has two types of cells, rectangular and square, and the guard cells of the stomata are dumbbell-shaped, and there are paraguard cells on the outside of the guard cells.
In terms of mesophyll, there is no obvious distinction between palisade tissue and sponge tissue, and it is an equifacial leaf. Only mesophyll cells have chloroplasts, no, like the inner epidermal cells of onion scale leaves, there are no chloroplasts. Epidermal cells generally do not contain chloroplasts, but have large vacuoles.
No, chloroplasts contain chlorophyll Chlorophyll is the site of photosynthesis It's also green, so it's called chlorophyll, but it also ages and dies So in the autumn the leaves turn yellow, that's when lutein increases and chlorophyll decreases.
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Anonymous users2024-02-07The structure of the leaf simply includes: blade, petiole and leaf.
We often say that leaves include epidermis, mesophyll, and veins.
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Anonymous users2024-02-06The structure of the observed blades is as follows:
The structure of the leaf is the epidermis, mesophyll, and veins. The leaf is the main component of the leaf and is generally green and flat. Leaf epidermal cells generally do not contain chloroplasts.
The mesophyll is composed of parenchyma cells containing chloroplasts between the upper and lower epidermis, and is the main site for photosynthesis of green plants. The leaf veins are mainly vascular bundles in the leaf, and the structure of the main veins and the lateral veins at all levels is not exactly the same.
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Anonymous users2024-02-051. The leaf veins are different.
The veins of grasses (monocots) are often parallel, while the dicots have reticular veins.
2. Epidermal cells are different from each other.
The epidermal cells of grass leaves are rectangular in regular arrangement, and the epidermal cells of dicot leaves are irregular in shape.
Poaceous leaves have epidermal hairs, while dicot leaves do not have epidermal hairs.
Among them, sweet potato leaves belong to grasses and tobacco leaves belong to dicots.
3. The pores are different.
The guard cells of grass leaves are dumbbell type with paraguard cells, and the guard cells of dicot leaves are kidney-type and have no guard cells.
4. The mesophyll is different.
Geminid leaves have palisade tissue and sponge tissue, while gramineous leaves do not.
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