General
Stomata closes when guard cells?
A) Lose water
B) Gain water
C) Mutate
D) None of these
Author:
Wasim Abbas
• Read More About This MCQ
Stomata are tiny openings on the surface of leaves that regulate gas exchange and water loss. They are controlled by guard cells, which change shape based on water content.
When guard cells gain water, they become turgid and open the stomata, allowing carbon dioxide to enter for photosynthesis. When they lose water, they become flaccid and close the stomata to prevent excessive water loss through transpiration.
This mechanism is essential for plant survival, especially in dry conditions. It helps maintain water balance while still allowing necessary gas exchange.
The other options are incorrect because gaining water opens stomata, and mutation is unrelated.
Thus, stomata close when guard cells lose water, making option A correct. This concept is fundamental in plant physiology and ecology.
General
Enzymes are made up of?
A)
Vitamins
B)
Carbohydrates
C)
Minerals
D)
Proteins
Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are primarily composed of proteins, which are made up of amino acids folded into specific three-dimensional structures.
This structure is crucial because it determines the enzyme’s active site, where substrates bind and reactions occur. Enzymes are highly specific, meaning each enzyme typically catalyzes a particular reaction.
Vitamins and minerals may act as cofactors or coenzymes, assisting enzyme function, but they are not the main structural components. Carbohydrates do not form enzymes.
Thus, proteins are the correct answer. This concept is fundamental in biochemistry and helps explain how metabolic processes occur efficiently in living organisms.
General
In stomach, pepsinogen is converted to?
A)
Enzyme
B)
Pepsin
C)
Proteins
D)
Amylase
Pepsinogen is activated by stomach acid into pepsin, which digests proteins into peptides.
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General
Attock fort built by which emperor?
A)
Babur
B)
Akbar
C)
Sher Shah Suri
D)
Aurangzeb
Attock Fort was built by the Mughal Emperor Akbar in 1581. It is located near the Indus River in present-day Pakistan and was constructed for strategic military purposes. The fort played a crucial role in defending the northwestern frontier of the Mughal Empire against invasions from Central Asia.
Akbar was known for strengthening the empire through administrative reforms and military infrastructure. Attock Fort was part of his broader strategy to secure trade routes and maintain control over key regions.
Babur founded the Mughal Empire but did not build this fort. Sher Shah Suri was known for road construction, including the Grand Trunk Road, while Aurangzeb ruled later and did not construct Attock Fort.
Thus, Akbar is the correct answer. The fort remains an important historical and architectural landmark in Pakistan today.
General
Length of Karakoram Highway?
A)
1300 kms
B)
1600 kms
C)
1900 kms
D)
2100 kms
Karakoram Highway length is about 1600 km connecting Pakistan and China.
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General
International day for desertification and drought observed on?
A)
17th January
B)
17th May
C)
17th June
D)
17th July
The International Day to Combat Desertification and Drought is observed annually on 17th June. This day was established by the United Nations to raise awareness about land degradation, desertification, and drought, which affect millions of people worldwide.
Desertification refers to the degradation of land in arid and semi-arid regions, often caused by deforestation, overgrazing, poor irrigation practices, and climate change. It leads to reduced agricultural productivity, food insecurity, and displacement of populations.
The observance encourages governments, organizations, and individuals to adopt sustainable land management practices. It also promotes international cooperation to address environmental challenges.
The other dates mentioned are incorrect because the UN officially designated 17th June for this purpose.
Recognizing such international days is important in exams as they reflect global awareness campaigns. Therefore, 17th June is the correct answer, highlighting efforts to combat environmental degradation and ensure sustainable land use.
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