This animation follows sunlight striking a leaf and traces the reactions inside: stomata opening and closing, chloroplasts trapping light with chlorophyll, and water and carbon dioxide combining to form glucose and oxygen. It also shows how made food travels through veins to be stored in roots, seeds, and stems. Explanations are given in Chichewa, making it useful for primary and secondary biology learners in Malawi studying plant nutrition.
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use this information to describe the process of photosynthesis. show animation of leaf receiving sunlight and animate the process inside the leaf what parts open and what closes and explain in Chchewa language. for the storage also show the seeds root etc and explain and animate that. photosynthesis photosynthesis Plant make their own food in leaves through photosynthesis. Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water. Photosynthesis in plants generally involves the green pigment, chlorophyll, and generates oxygen as a by-product. There are several reasons that enable leaves carry out the process of photosynthesis effectively and efficiently. Tip Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water. Explanation: Activity Describe adaptations of leaves for photosynthesis. Compare your answer with the following: i) Presence of chlorophyll- chlorophyll is found in chloroplast and helps to trap or capture sunlight. ii) Leaves are broad and flat- this helps leaves to have a large surface area for capturing more sunlight. iii) Leaves have a network of veins- veins have vascular bundles which transport water, mineral salts and manufactured food using their xylem and phloem. iv) Leaves have transparent cuticle- this allows light to enter and penetrate into the leaf cells. It also reduces water loss by evaporation due to the presence of wax v) Presence of stomata- the stomata are small pores on the surface of the leaf. The stomata allow air to enter or get out. vi) The spongy mesophyll cells are irregularly arranged- this arrangement leaves spaces that allow efficient exchange of gases. vii) Leaves have thin leaf blades- t his provides a short distance through which carbon dioxide can diffuse to the photosynthetic cells (mesophyll cells). viii) Arrangement of mesophyll cells- the palisade cells have large number of chloroplasts and are located on the upper part of the leaf. Spongy mesophyll cells have few chloroplasts are located on the lower part of the leaf however they provide spaces in between the cells for free circulation of gases. ix) Leaf arrangement along the stem- leaves are arranged in such a way that they do not overshadow or overlap hence each leaf gets enough sunlight. You call this mosaic arrangement. Gaseous exchange in leaves You remember that leaves have openings called stomata for gaseous exchange. Have you ever dropped a fresh leaf into hot water? What can you observe if you do so? You can see bubbles on both sides of the leaf. Which side gives more bubbles? You get more bubbles on the lower side of the leaf. However, this is true for mesophytes. Mesophytes are plants that grow in places that are not too dry nor too wet. During the day, plants make use of carbon dioxide in the process of photosynthesis. Carbon dioxide enters the plant through the process of diffusion. This means there is lower carbon dioxide concentration inside the leaf than outside. On the other hand, oxygen is more in the inside than outside since oxygen is released from the process of photosynthesis. At night, there is more oxygen outside the leaf than inside hence oxygen enters from the atmosphere to the leaf cells. Carbon dioxide comes from the atmosphere and enters the leaf. Plant cells In junior secondary, you learnt about cells. You discussed differences and similarities between plant and animal cells. In this section, you will focus on plant cells. What are some of the plants cells that you know? You can think of guard cells, palisade cells, spongy cells, epidermal cells, and many more. Not all plant cells make food. Green plants make food in mesophyll cells and guard cells. These cells contain chlorophyll. Most of the plant food is made in mesophyll cells. See figure 3.6 showing the structure of a guard cell. The structure of a guard cell Activity Describe mechanism of guard cells that leads to the closure and opening of the stoma. Compare your answer with the following guard cells: a) These open and close the stoma thereby regulating water loss from the leaf b) When guard cells get water from the surrounding cells, they become turgid hence look semi-circular. This is so because the cell wall of guard cells is thicker in the inner surface, therefore, it cannot stretch as much as the outer surface. This is due to having unequal distribution of cellulose in the cell wall. c) When this happens, the guard cell opens the stoma. d) For the guard cell to close the stoma, the guard cell loses water hence the inner surface of a guard cell flattens thereby closing the stoma. Mesophyll cells The following figure shows the structure of the mesophyll cell. Study the diagram ca Structur Audience: middle schooler