1. Why should we add more plants to our surroundings? 2. Describe the structure of a chloroplast with a suitable diagram. 3. Describe the structure of a stoma with a diagram. 4. Describe an experiment to prove that starch is formed in leaves during photosynthesis. 5. How would you prove that oxygen is formed during photosynthesis? 6. What is the significance of photosynthesis? 7. How would you prove that light is essential for photosynthesis? 8. Place a variegated garden croton in sunlight for a day. Test one of its leaves with iodine solution. Explain what happens. 9. Compare how photosynthesis and respiration occur in plants.
Answers
Answer:
1.ans- Trees improve air quality by absorbing toxic chemicals from the atmosphere. Pollutant gases and odors such as ammonia, ozone, nitrogen oxides and sulfur dioxide are all absorbed by the leaves of trees. Trees also filter particulates from the air, thus making it clean and free of toxic materials.
2.ans-Structure of Chloroplasts
Chloroplasts are oval-shaped and have two membranes: an outer membrane and an inner membrane. Between the outer and inner membrane is the intermembrane space approximately 10-20 nm wide. The space within the inner membrane is the stroma, the dense fluid within the chloroplast.
3ans- Stomata are small pores present in the epidermis of leaves. They regulate the process of transpiration and gaseous exchange. The stomatal pore is enclosed between two bean-shaped guard cells. ... The pores, the guard cells, and the subsidiary cells together constitute the stomatal apparatus.
4.ans-When you put iodine on the leaves, one of them will turn blue-black and the other will be a reddish-brown. Iodine is an indicator that turns blue-black in the presence of starch. The leaf that was in the light turns blue-black, which demonstrates that the leaf has been performing photosynthesis and producing starch.
5.ans- Experiment to show that oxygen is produced during photosynthesis. Place water plant in a beaker containing pond water. Cover the plant with short stemmed funnel. ... A glowing splinter bursts into the flame shows the presence of oxygen.
6ans- It provides food for all living beings but the process occurs in the leaves of green plants. - It fixes and balances the amount of carbon dioxide and oxygen in the atmosphere by plants exhaling oxygen and animals and humans exhaling carbon dioxide.
7.ans-The leaf which turned blue-black is a leaf which is placed in sunlight, and photosynthesis occurred and starch was produced. - So starch is produced only in the leaves which are exposed to sunlight, and this proves that sunlight is very essential for plants to do photosynthesis.
8.Step 1: Take a potted plant with variegated leaves – like a money plant or croton. In the experiment, a variegated leaf is used because some part of the leaf is green in color, while some part is non-green. Owing to the presence of chlorophyll, the green part of the leaf is green and can perform photosynthesis. The non-green component has no chlorophyll and thus does not conduct photosynthesis.
-Step 2: Hold the plant for three days in a dark space, so that all the starch is used up.
The plant is then kept in the dark for 2-3 days so that all the food processed is used up in the form of starch.
In the absence of light, there is no photosynthesis and, thus, no more food production takes place.
-Step 3: Now keep the plant for about six hours in sunlight.
The plant is then placed for 6 hours in sunlight to allow for photosynthesis. Carbohydrate formation occurs only in the green parts of the plants, due to photosynthesis.
-Step 4: Pluck out a plant leaf. Label and trace the green areas within it on a sheet of paper.
The starch-containing leaf is plucked and labeled for green areas which will help us compare the results of the iodine test further.
-Step 5: Dip the leaf a few minutes in boiling water. Then immerse it into an alcohol-containing beaker. Place the above beaker carefully in a water-bath and heat until the alcohol starts boiling.
The leaf is treated with alcohol so that after treatment with iodine the leaf loses its green color due to the chlorophyll pigment and takes up the blue-black color.
-Step 6: Now dip the leaf for a few minutes in a dilute iodine solution. Take the leaf out and rinse off the iodine.
-The green parts of the variegated leaf have chlorophyll in it. Only those sections may thus carry out photosynthesis and generate food (starch). Starch reacts with iodine in the presence of iodine and gives it a blue-black color. This development of color indicates the presence of starch in the leaf and thus shows that chlorophyll is essential to the photosynthesis process.
9.ans-Photosynthesis converts carbon dioxide and water into oxygen and glucose. Glucose is used as food by the plant and oxygen is a by-product. Cellular respiration converts oxygen and glucose into water and carbon dioxide. Water and carbon dioxide are by- products and ATP is energy that is transformed from the process.
