Photosynthesis+Experiment+Buffet+(Practical)

__Photosynthesis Experiment Buffet (Practical)__

**Station 1: Is sunlight necessary for photosynthesis?**


 * 1) The leaf with iodine that has turned dark blue was exposed to sunlight and the other (remains browinsh yellow) was not. The dark blue leaf shows presence of starch, which indicates that the plant has produced glucose during the process of photosynthesis and it has been stored as starch in the starch granules.
 * 2) To find out if there is a presence of starch which will indicate if glucose has been stored as starch in the lead after photosynthesis has taken place.
 * 3) Sunlight is needed for photosynthesis.

**Station 2: Is chlorophyll necessary for starch formation during photosynthesis?**


 * 1) Starch can only be formed when there is presence of chlorophyll.

**Station 3: Factors affecting photosynthesis.**


 * 1) The set-up with the higher light intensity will have a higher rate of photosynthesis.
 * 2) The air bubbles formed contain oxygen gas. Oxygen gas does not extinguish a burning splint.
 * 3) The aim of this experiment is to find out how different light intensities affect the rate of photosynthesis in water plants such as the Hydrilla.

**Station 4: Stomata Count.**

2 and 3. More stomata are found on the lower epidermis of the plant than when compared to the upper epidermis. This helps to shield the stomata from being exposed to the sunlight and high temperature and helps to prevent water loss through transpiration so that more water is available for photosynthesis.
 * 1) The underside of the leaf contains more stomata.

**Station 5: Cross Section of a Leaf.**


 * 1) The upper epidermis, the palisade mesophyll, the spongy mesophyll, the lower epidermis
 * 2) The upper epidermis (together with the waxy cuticle) acts like a convex lens and focuses sunlight onto the leaves. They prevent water loss through evaporation and protects the leaf from mechanical damage. The palisade mesophyll layer is packed with chloroplasts to ensure maximum absorption of sunlight and the chloroplasts orientate vertically so that they are better exposed to the sunlight.The spongy mesophyll has a loose arrangement of irregular shaped cells with large extracellular spaces and this allow efficient diffusion of carbon dioxide needed for photosynthesis.

**Station 6: Cross Section of Root.**


 * 1) The root contains a vascular bundle with xylem and phloem tubes that help to transport water and nutrients to the leaves of the plant respectively. These materials are transported by the roots due to the high pressure that is created at the top of the water chain due to transpiration. Also, the root is able to take in soil water due to capillary action which creates further pressure for it to be transported upwards.
 * 2) The thickness of the root is optimum to ensure maximum absorption of water and mineral salts through capillary action.

**Station 7: Capillary Action for Water Transport.**


 * 1) The thinnest tube has the highest water level.
 * 2) This is because the thinner tube has a smaller volume so the liquid level is higher.

**Station 8**

Also, as water molecules evaporate out of the leaves through transpiration, other water molecules replace them from the xylem of the leaf veins. Cohesion of water molecules to one another and adhesion to xylem wall by hydrogen bonds creates a “water chain”. As the top of the “water chain” is pulled up by the evaporation, the rest of the chain, all the way down to the roots, come along as well. As the molecules of the water chain retreat up the xylem in the roots, the decreased water pressure within the root xylem and the surrounding extracellular space causes water to enter from the soil water, thus steadily replenishing the bottom of the chain.
 * 1) When the plant transpires, it produces water vapour that is produced into the surrounding through the stomata on the leaves.
 * 2) Transpiration.
 * 3) This process is necessary for osmoregulation for the plant. When there is excess water in the plant, the water potential of the leaves decrease and therefore, the plants start giving out excess water in the leaves in the form of water vapour.

**Station 10: Photosynthetic Plants**

2. The plant that grows in shady areas has a greater composition of photosynthetic pigments so that it can maximize the absorption of sunlight.