In photosynthesis, oxygen is released from: MCQ with Answer and Explanation

Question
In photosynthesis, oxygen is released from:
A. Carbon dioxide
B. Chlorophyll
C. Water
D. Glucose
Answer: Option C
Solution (By JKSSB Mock Tests)
During the light reactions of photosynthesis, photolysis of water occurs at photosystem II, splitting water into protons, electrons, and molecular oxygen. The oxygen comes from water, not CO₂. This was demonstrated by using isotopically labeled oxygen (H₂O¹⁸). Glucose is formed in the Calvin cycle. Chlorophyll absorbs light but does not provide oxygen. The overall equation: 6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O.
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Question #1
The scientist who discovered the phenomenon of transformation in bacteria was:
A. Griffith
B. Chase
C. Hershey
D. Avery
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Correct Answer: Option A

Explanation:
Frederick Griffith in 1928 demonstrated transformation by showing that heat-killed virulent pneumococci could transfer virulence to live non-virulent bacteria. Avery et al. later identified the transforming principle as DNA.
This question belongs to: Science Biology
Question #2
Identify the correct statement about the human reproductive system:
A. The prostate gland produces sperm.
B. The ovum is released from the uterus during ovulation.
C. Fertilization occurs in the ovary.
D. The vas deferens carries sperm from the testes to the urethra.
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Correct Answer: Option D

Explanation:
Vas deferens transports sperm. The ovum is released from the ovary, fertilization occurs in the fallopian tube, prostate produces seminal fluid.
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Question #3
The disease 'pellagra' is caused by the deficiency of:
A. Vitamin B₂ (Riboflavin)
B. Vitamin B₁ (Thiamine)
C. Vitamin B₆ (Pyridoxine)
D. Vitamin B₃ (Niacin)
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Correct Answer: Option D

Explanation:
Pellagra, characterized by dermatitis, diarrhea, and dementia (3 Ds), is caused by a deficiency of niacin (vitamin B₃) or its precursor tryptophan. It is common in populations with corn-based diets lacking tryptophan. Beriberi is due to B₁ deficiency, cheilosis to B₂, peripheral neuropathy to B₆. Niacin is a component of coenzymes NAD and NADP.
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