Observe the structure of the blade, what is the experimental procedure

1. 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 **. ）

Junior Biology Experiment: Observe the structure of leaves.

1. Extraction and separation of pigments in chloroplasts.

2. The use of high-power microscope and observation of chloroplasts.

3. Chloroplasts are found in the cytoplasmic matrix and are generally green, flattened ellipsoidal or spherical. Its morphology and distribution can be observed with a high-powered microscope. The above is the experimental principle of observing the leaves of plants.

The 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.

1. 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.

Summary. Hello, it's a pleasure to answer for you. It is better to use the part of the leaf that contains chloroplasts. Because the site of photosynthesis in the same plant is in the chloroplast of the cell, the variable should be the presence or absence of chloroplasts when designing a control experiment, and all other conditions are the same

Hello, I'm honored to answer for you. It is better to use the part of the leaf that contains chloroplasts. Because in the same plant body, the place of photosynthesis is in the chloroplast of the cell, so when designing the liquid head control experiment, the variable should be the presence or absence of chloroplasts, and other conditions are the same

Hello! We will be happy to answer your question again, so please be patient.

Well. Morphology and distribution characteristics of mitochondria.

Okay, please be patient for a few minutes.

Hello! Let's solve the last problem first: mitochondrial shape, distribution characteristics shape:

The shape and size of mitochondria often vary greatly with different cell types and physiological conditions, and are very small balls, rods, or filaments under the light microscope, and rod-shaped ones are the majority. Under the electron microscope, in addition to the common rod shape, round shape, sometimes ring, dumbbell shape, or other simple travel shapes can be seen. The diameter of the mitochondria is within the circumference of microns, and the length is 2 3 micrometers, and the longest can be 10 microns.

Distribution characteristics: Mitochondria have about 15 50 proteins distributed in the matrix and intermembrane cavity, and the rest are bound to the membrane.

With the increase of leaf area index, crop yield will also increase. However, when the index increases to a certain limit, it will lead to the closure of the crop growth environment, the lack of light in the lower leaves, the photosynthetic efficiency will be affected, and even the fruit color will be affected, and the yield will be reduced. It can be seen that the practical significance of grasping the optimal leaf area index in greenhouse production should not be underestimated.

The QT-2012 portable leaf area meter can be used to quickly measure most common plant leaves in vitro and non-ex vivo, and obtain parameters such as leaf area, circumference, length, and width. It can be widely used in the teaching and research of plant physiology and ecology; Cultivation and breeding of crops, trees, flowers, fruit trees and vegetables. It is suitable for the application of laboratories in colleges and universities and agricultural and forestry research departments.