Life Processes in Plants

Sanjana says a plant makes its own food in its leaves, from sunlight, air and water. Yug says no — a plant takes its food from the soil through its roots, the way we eat through our mouths. Who is right?

On a sunny morning, Dhanush and Mahi tie a clear plastic bag over a leafy branch of a potted plant. By afternoon, the inside of the bag is covered with water droplets. Dhanush says moisture from the outside air must have got into the bag. Mahi says the water came out of the leaves themselves. Whose explanation is correct?

Vaishnavi says plants don't need to respire the way animals do — they only take in carbon dioxide and give out oxygen. Rudra says plants respire all the time, day and night, just like animals, using oxygen to release energy from their food. Who is right?

In a class experiment, a potted plant is kept in a dark cupboard for two days. Then a strip of black paper is clipped over part of one leaf, and the plant is placed in sunlight for a day. Finally the leaf is tested with iodine (the teacher first boils it in alcohol to remove the green colour). Prithvi predicts that only the uncovered part will turn blue-black. Saloni says the whole leaf will turn blue-black, because the covered part is still green and still has chlorophyll. Whose prediction is correct?

Prakriti is so excited about her new mint plant that she waters it five times a day, keeping the soil in the pot soaking wet all the time. She says more water can only help, because plants need water to make food. Her neighbour Ruhi warns that the roots could die this way. Who is right?

At the vegetable market, Tanmay sees a bunch of red amaranth (lal saag) with deep red leaves. He says these leaves still make food by photosynthesis — their chlorophyll is just hidden under the red colour. Gargi says red leaves can't have chlorophyll, because chlorophyll is green, so this plant must get its food some other way. Whose reasoning holds up?