The pigment that absorbs light in photosystem I is primarily: MCQ with Answer and Explanation

The pigment that absorbs light in photosystem I is primarily:
A. P700
B. Xanthophyll
C. P680
D. Chlorophyll b
Answer: Option A
Solution (By JKExamLibrary)
P700, a specialized chlorophyll a, is the reaction center of photosystem I, absorbing far-red light (700 nm). P680 is the reaction center of photosystem II. Chlorophyll b and xanthophyll are accessory pigments.

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Practice More Biology Questions

Question #1
RNA interference (RNAi) is a technique used in genetic engineering to silence specific genes. In the development of nematode-resistant transgenic tobacco plants, the source of the silencing RNA was:
A. The nematode itself (Agrobacterium-mediated delivery of nematode genes)
B. The plant's own genome
C. A virus
D. A bacterium

Correct Answer: Option A


Explanation:
RNAi is a cellular defense mechanism in eukaryotes that silences specific mRNA. To create nematode-resistant tobacco, scientists used Agrobacterium as a vector to introduce nematode-specific genes into the host plant. The plant then produced both sense and anti-sense RNA for these genes. The double-stranded RNA (dsRNA) formed triggered the RNAi pathway, degrading the nematide's mRNA when it tried to express those essential genes inside the plant roots, killing the nematode.

This question belongs to: Science Biology
Question #2
The 'Humulin' was the first genetically engineered human therapeutic product approved for clinical use. It is:
A. Human Interferon
B. Human Albumin
C. Human Insulin
D. Human Growth Hormone

Correct Answer: Option C


Explanation:
Humulin is the trade name for the first genetically engineered human insulin, approved by the FDA in 1982. Prior to this, insulin for diabetic patients was extracted from the pancreases of pigs and cows, which could cause allergic reactions. Humulin is produced by inserting the human insulin genes into Escherichia coli bacteria, which then synthesize the exact amino acid sequence of human insulin, eliminating the risk of animal-derived immune reactions.

This question belongs to: Science Biology
Question #3
The Fluid Mosaic Model of the cell membrane was proposed by which scientists?
A. Schleiden and Schwann
B. Singer and Nicolson
C. Watson and Crick
D. Robertson and Danielli

Correct Answer: Option B


Explanation:
The Fluid Mosaic Model of the plasma membrane was proposed by S. Jonathan Singer and Garth Nicolson in 1972. It describes the cell membrane as a dynamic, fluid structure composed of a phospholipid bilayer with globular proteins embedded or attached, moving laterally within the lipid matrix.

This question belongs to: Science Biology