Explanation: A warm boot, also known as a "soft reboot," refers to the process of restarting a computer system without completely shutting down the power. This is typically done using the operating system's restart function, which reinitializes the system and reloads the operating system without turning off the hardware. Here are the terms explained again for clarity: Cold booting (A): Also known as a "cold start," this refers to starting a computer from a completely powered-down state. This involves turning on the power switch and initializing the system from scratch. Logging off (B): This refers to ending the current user session, allowing another user to log in without shutting down the computer. It does not restart the computer. Shut down (C): This refers to turning off the computer completely, ending all processes and cutting power to the system. Warm booting (D): This is the process of restarting a computer that is already on, without turning off the power. It involves reloading the operating system and reinitializing the hardware and software components. In summary, warm booting is the correct term for restarting a computer system without completely shutting down the power.

Explanation: ASTROSAT is India's first dedicated multi-wavelength space observatory. It was launched by the Indian Space Research Organisation (ISRO) to conduct detailed studies of celestial sources in different wavelengths, including X-rays, ultraviolet, and visible light. Its mission is to observe and analyze the universe's various phenomena, contributing to the field of astronomy and astrophysics.

Explanation: Organism (A): An individual living entity, such as a plant, animal, bacterium, etc. Population (B): A group of organisms of the same species living in a particular area. Biome (C): A large geographic area characterized by specific climate conditions and particular types of plants and animals. Examples include deserts, forests, grasslands, and tundras. Ecosystem (D): A community of living organisms interacting with each other and their non-living environment within a specific area. Ecosystems can vary greatly in size. Among these, a biome is the largest ecological unit, encompassing multiple ecosystems and covering extensive geographical areas.

Explanation: Lysosomes are membrane-bound organelles that contain digestive enzymes. They are responsible for breaking down waste materials, cellular debris, and foreign substances within the cell. If a cell is damaged or undergoing apoptosis (programmed cell death), lysosomes can release their enzymes to digest the cell's components, hence the term 'suicidal bags'.

Explanation: At 4°C, water reaches its maximum density, which is an unusual property compared to most other substances. As water cools below 4°C, it begins to expand again, which is why ice is less dense than liquid water and floats.

Explanation: White blood cells (WBCs), also known as leukocytes, are a crucial part of the immune system. They help the body fight infections and other diseases. There are several types of white blood cells, including lymphocytes (such as B cells and T cells), neutrophils, monocytes, eosinophils, and basophils, each playing a unique role in the immune response.