Explanation

• The kidneys are the primary organs responsible for removing waste and excess substances from the body through urine.
• They filter the blood and regulate electrolyte levels, playing a critical role in maintaining overall bodily function.

Explanation

• The electricity from a cell (such as a battery) is Direct Current (DC).
• It is the flow of electric charge in one direction only, without changing direction.
• This is the type of current used in electronic devices such as smartphones, laptops, and televisions.

Explanation

• Neurons are the basic structural and functional units of the nervous system.
• They are specialized cells that transmit and process information through electrical and chemical signals.

Explanation

• The stratosphere is the layer of the atmosphere where the ozone layer is present.
• It extends from approximately 12 to 50 kilometers (7.5 to 31 miles) above the Earth's surface.
• The ozone layer is a critical component of the Earth's atmosphere, as it absorbs harmful ultraviolet (UV) radiation from the sun, protecting life on Earth.

Explanation

• The molecular model of DNA that suggests the basic mechanism of replication was proposed by James Watson and Francis Crick.
• They proposed the double helix model of DNA in 1953, which revolutionized our understanding of genetic information storage and replication.

Explanation

• An optical instrument used to measure the properties of visible light is called a Spectroscope.
• It analyzes the composition and properties of materials based on the light they emit or absorb.
• It helping us understand the physical and chemical properties of objects in the universe.

Explanation

• Mercury is a silvery-white liquid metal that was traditionally used in clinical thermometers due to its high coefficient of expansion.
• It allowing for accurate temperature measurements.

Explanation

When water cools from 4°C to 0°C, ice crystals begin to form 

When water freezes, the water molecules form a lattice that increases the volume.

As a result, the density decreases

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ND22-1-2023

Explanation

• The stomach is an organ involved in digestion, not waste elimination.

1. Lungs: remove carbon dioxide through exhalation
2. Kidneys: filter waste and excess substances from the blood, producing urine
3. Skin: removes waste through sweating
4. Liver: detoxifies harmful substances and aids in their removal

Explanation

• Inheritance refers to the passing down of traits or characteristics from parents to their offspring through the transmission of genetic information.
• This occurs through the transmission of DNA from one generation to the next.