Mayukh Dutta, Class VII, Sri Sai Vidya Vihar, Golaghat

Question: Why does an apple turn brown when we cut it?

Answer: The cut apples turn brown due to a chemical reaction called enzymatic browning. Apples contain an enzyme called polyphenol oxidase (PPO) and some organic compounds called polyphenols. Under normal conditions, the PPO and polyphenols present in the apple do not react to each other. Cutting of the apples damages the cells and exposes them to oxygen. In presence of oxygen, PPO and polyphenols react with each other which leads to enzymatic browning of the apple tissues.

Priyanki Saikia, Class VII, Sri Sathya Sai Vidya Vihar, Golaghat

Question: Why do tears come to our eyes while cutting onions?

Answer: Onions contain certain enzymes and acids which are exposed when we cut them. They react with each other and form a chemical called syn-propanethial-S-oxide. This substance is a volatile and easily vaporizes into sulphur gas. Because of this gas only we feel a burning sensation in our eyes while cutting onions. This triggers the formation of tears as a defensive reaction of the body.

Kapinjal Kiran Gogoi, Class VII, Pragjyotika English School, Titabor

Question: Do identical twins have identical fingerprints?

Answer: No, identical twins do not have identical fingerprints. Although identical twins have identical genome, fingerprints are influenced by more than just genes. Fingerprints are generated before birth while the growing foetus is in the mother’s womb. They are influenced by factors such as the position of the foetus in the womb, nutrition, blood pressure and even how fast the fingers grow. Fingerprints are fully developed by the time a foetus is about 6 months old but can become more marked after birth.

Isha Hazarika, Class IV, Brahmaputra Jatiya Vidyalaya, Golaghat

Question: Why don’t birds get electrocuted when they sit on electrical wires?

Answer: To be electrocuted, one must be in a complete circuit. This means that to get electrocuted, the bird must touch both a positive wire, and a negative or neutral wire (or the ground). While a bird touches the ground while touching a live electric wire, the ground would act as a neutral wire and the current would flow through the bird electrocuting it. Similarly, if the bird sits on the positive wire and touches the other wire, it will also complete a circuit and get electrocuted. However, when the bird sits only on one wire, it will be safe because the circuit is not complete.