Explanation: In GM food, the term GM stands for Genetically Modified. These are foods produced from organisms (plants or animals) whose genetic material (DNA) has been altered using modern biotechnology or genetic engineering techniques. This modification is done to introduce desirable traits such as pest resistance, drought tolerance, higher yield, or improved nutritional value. A common example is Bt cotton, which contains a gene from the bacterium Bacillus thuringiensis that provides resistance to insect pests.

Explanation: Vitamins are classified into two categories based on their solubility — fat-soluble and water-soluble. Vitamin C (ascorbic acid) and the B-complex vitamins are water-soluble, meaning they dissolve in water and are not stored in the body. Therefore, they must be consumed regularly through diet. Deficiency of Vitamin C causes scurvy, characterized by bleeding gums and delayed wound healing.

Explanation: The thyroid gland is the largest endocrine gland in the body. It is a butterfly-shaped gland situated in the neck region, just below the larynx. It secretes the hormones thyroxine (T₄) and triiodothyronine (T₃), which control metabolism, growth, and energy utilization. The thyroid also produces calcitonin, which helps regulate calcium levels in the blood.

Functions of the Thyroid Gland:

• Regulates metabolic rate (BMR)
• Influences growth and development
• Maintains body temperature and energy balance
• Regulates calcium metabolism via calcitonin

Disorders:

• Hypothyroidism: Leads to goitre, myxedema, or cretinism
• Hyperthyroidism: Leads to weight loss, anxiety, and increased heart rate

Explanation: Sound waves in air are longitudinal waves, meaning the particles of the medium vibrate back and forth in the same direction as the wave travels. These waves require a material medium (like air, water, or solids) for propagation and cannot travel through a vacuum.

Explanation: The intensity of sound is measured in decibels (dB). The decibel is a logarithmic unit that expresses the ratio of a sound’s intensity compared to a reference level (usually the faintest sound the human ear can detect, known as the threshold of hearing). The higher the decibel value, the louder the sound. For example, normal conversation is around 60 dB, traffic noise is about 80–90 dB, and sounds above 120 dB can cause pain or hearing damage.

Explanation: The quality of petrol (gasoline) is measured by its octane number, which indicates the fuel's resistance to knocking (premature ignition) in an internal combustion engine; a higher octane number gives better performance and smoother operation.

Explanation: An anemometer is a meteorological instrument used to measure wind speed and direction. It is an essential tool in weather stations, aviation, and marine forecasting.

Working Principle: The cup anemometer has three or four cups that rotate with the wind. The rotation speed is proportional to wind velocity. Advanced types also detect wind direction.

Types of Anemometers:

• Cup: Measures wind speed using rotating cups.
• Vane: Measures both speed and direction.
• Hot-wire: Uses heat loss to measure air flow.
• Ultrasonic: Uses sound waves for precise measurement.