1.
_________present in air is needed for respiration.
Correct Answer
B. Oxygen
Explanation
Oxygen is needed for respiration because it is used by our cells to produce energy through a process called cellular respiration. During respiration, oxygen is taken in by the lungs and delivered to the cells through the bloodstream. In the cells, oxygen combines with glucose to produce ATP, which is the energy currency of the body. Without oxygen, cells cannot produce enough ATP to sustain vital functions, leading to cell death and ultimately, the cessation of respiration.
2.
________is one of the wind instrument.
Correct Answer
A. Flute
Explanation
The flute is a wind instrument that is played by blowing air across the mouthpiece. It produces sound by vibrating the air column inside the instrument. The other options, violin and drums, are not wind instruments. The violin is a string instrument that is played with a bow, and the drums are percussion instruments that are played by striking or hitting them.
3.
_________is used to store living cells.
Correct Answer
A. Liquid nitrogen
Explanation
Liquid nitrogen is used to store living cells because it can maintain a very low temperature of around -196 degrees Celsius. This extremely low temperature helps to preserve the cells by slowing down their metabolic processes and preventing degradation. Additionally, the low temperature of liquid nitrogen prevents the formation of ice crystals, which can damage the cells. Therefore, liquid nitrogen is commonly used in laboratories and cryogenic storage facilities to store living cells for long-term preservation.
4.
________is used in fire extinguishers.
Correct Answer
C. Carbon dioxide
Explanation
Carbon dioxide is used in fire extinguishers because it is a non-flammable gas that can displace oxygen, effectively smothering the fire. When carbon dioxide is released from the extinguisher, it creates a blanket of gas that reduces the oxygen concentration around the fire, preventing it from spreading and extinguishing it. Additionally, carbon dioxide is safe to use on electrical fires and does not leave behind any residue or damage the surrounding area.
5.
Root nodules containing _________in some plants.
Correct Answer
C. Nitrogen
Explanation
Root nodules contain nitrogen in some plants. These nodules are formed through a symbiotic relationship between certain plants and nitrogen-fixing bacteria. The bacteria convert atmospheric nitrogen into a form that can be used by the plants for their growth and development. This process, known as nitrogen fixation, is crucial for the nitrogen cycle and plays a vital role in maintaining soil fertility and supporting plant growth. Therefore, the correct answer is nitrogen.
6.
Air is made up of oxygen only. True or false?
Correct Answer
B. False
Explanation
The statement "Air is made up of oxygen only" is false. Air is a mixture of gases, with the primary components being nitrogen (approximately 78%) and oxygen (approximately 21%). Other gases such as carbon dioxide, argon, and trace amounts of various gases are also present in air. Therefore, air is not solely composed of oxygen.
7.
Carbonated drinks are bad for health. True or false?
Correct Answer
A. True
Explanation
Carbonated drinks are bad for health because they often contain high amounts of sugar, artificial sweeteners, and empty calories. Regular consumption of these drinks has been linked to various health issues such as obesity, tooth decay, diabetes, and increased risk of heart disease. Additionally, the carbonation in these beverages can lead to bloating, indigestion, and acid reflux. Therefore, it is advisable to limit the intake of carbonated drinks for better overall health.
8.
Plants need oxygen for their growth. True or false?
Correct Answer
B. False
Explanation
While plants do need oxygen, they primarily rely on carbon dioxide for their growth through the process of photosynthesis. Oxygen is mainly used by plants during respiration, similar to animals, but it is not the primary requirement for their growth.