Explanation: Malaria and Trichomoniasis are both protozoan diseases, not bacterial. Malaria is caused by Plasmodium species (transmitted by female Anopheles mosquitoes), while Trichomoniasis is caused by Trichomonas vaginalis, a sexually transmitted protozoan infection. Unlike bacterial diseases, these are treated using antiprotozoal drugs rather than antibiotics.

Explanation: The weight of a person depends on the gravitational force exerted by a celestial body. The Moon’s gravity is only about 1/6th that of the Earth’s because it has much less mass and a smaller radius. Therefore, an object or person weighing 60 kg on Earth would weigh only about 10 kg on the Moon. Although mass remains constant everywhere, weight changes according to the local gravitational acceleration (g). Hence, lower gravity results in lower weight on the Moon.

Explanation: The rarest blood type in the world is AB⁻ (AB negative). It is found in less than 1% of the global population. People with AB⁻ blood can receive red blood cells from all Rh-negative blood types, but they can donate only to other AB individuals.

Explanation: The nerve cell or neuron is the longest cell in animals. It consists of a cell body, dendrites, and a long fiber called the axon. In humans, the axon of a motor neuron can be over 1 meter long (from the spinal cord to the toes). This structure helps transmit electrical impulses rapidly across the body, allowing coordination and communication between organs.

Explanation: Natural gas is a non-renewable source of energy because it is formed from fossilized organic matter over millions of years and cannot be replenished quickly. In contrast, geothermal energy, flowing water, and biomass are renewable as they can be naturally regenerated over short periods.

Explanation: Sodium (Na⁺) plays a crucial role in the transmission of nerve impulses in the human body. Nerve cells (neurons) transmit signals through an electrochemical process known as the nerve impulse or action potential. During this process, the movement of sodium (Na⁺) and potassium (K⁺) ions across the nerve cell membrane generates an electrical charge. The rapid influx of sodium ions causes depolarization, which allows the nerve impulse to travel along the neuron, ensuring proper communication between the brain, spinal cord, and body.

Explanation: The longest day in the Southern Hemisphere occurs on 22nd December, which marks the Summer Solstice in that hemisphere. On this date, the South Pole is tilted toward the Sun, resulting in longer daylight hours and shorter nights. Conversely, at the same time, the Northern Hemisphere experiences its winter solstice—the shortest day and longest night of the year. After 22nd December, the days in the Southern Hemisphere gradually begin to shorten.

Explanation: Dissolved oxygen (DO) is the amount of oxygen available in water for aquatic organisms to breathe. For the healthy survival of most aquatic life, the DO level should be between 4 and 6 mg/L. Levels below 3 mg/L can lead to stress or suffocation, especially for fish and aerobic microorganisms. Higher DO levels are typical of clean, cold, and well-aerated waters, while polluted or stagnant waters often have lower oxygen levels due to organic decay.

Factors Affecting DO Levels:

• Temperature (higher temperature = lower DO)
• Organic pollution and bacterial activity
• Photosynthesis by aquatic plants and algae
• Water turbulence and aeration

Explanation: In household electrical wiring, all the given statements are correct: the red insulated wire is the live (phase) wire, the black insulated wire is the neutral wire, and the green insulated wire is used for earthing to ensure safety by preventing electric shocks.

Explanation: The term LASER stands for Light Amplification by Stimulated Emission of Radiation. A laser produces a highly coherent, monochromatic, and intense beam of light by amplifying light through the process of stimulated emission. In this process, atoms or molecules in an excited state emit photons in phase with incoming photons, resulting in a strong, directed beam. Lasers are widely used in medicine, communication, industry, defense, and scientific research.