In a plant cell, the turgor pressure is maintained mainly by the: MCQ with Answer and Explanation

In a plant cell, the turgor pressure is maintained mainly by the:
A. Cell wall
B. Central vacuole
C. Chloroplast
D. Plasma membrane
Answer: Option B
Solution (By JKSSB Mock Tests)
The central vacuole occupies a large volume of a mature plant cell and stores water, creating turgor pressure against the cell wall, which maintains cell rigidity and plant structure. The cell wall provides mechanical support but turgor pressure generated by the vacuole is essential for maintaining turgidity, especially in herbaceous plants.

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Question #1
The term 'operon' in genetics refers to:
A. A DNA repair mechanism
B. A single gene with multiple functions
C. A set of linked genes regulated by a single promoter
D. A viral DNA integrated into host genome

Correct Answer: Option C


Explanation:
An operon is a functional unit of DNA in prokaryotes containing a cluster of genes under the control of a single promoter, transcribed as a single mRNA. Example: lac operon. It includes operator, promoter, and structural genes. Operons allow coordinate regulation. Eukaryotes generally lack operons.

This question belongs to: Science Biology
Question #2
In human nutrition, the 'Glycemic Index' (GI) of a food measures:
A. The caloric value of the food
B. The total carbohydrate content per 100 grams
C. The amount of dietary fiber present in the food
D. The rate at which the food raises blood glucose levels after consumption

Correct Answer: Option D


Explanation:
The Glycemic Index (GI) is a numerical scale (from 0 to 100) that measures how quickly a carbohydrate-containing food raises blood glucose levels compared to a reference food (usually pure glucose or white bread). Foods with a high GI (like white bread, sugary drinks) cause a rapid spike in blood sugar, while low GI foods (like whole grains, legumes) cause a slower, more gradual rise. It does not measure total carbohydrate amount.

This question belongs to: Science Biology
Question #3
Graves' disease is an autoimmune disorder characterized by hyperthyroidism. It is caused by the production of autoantibodies that:
A. Target the parathyroid glands
B. Mimic TSH and continuously stimulate the TSH receptors
C. Destroy the thyroid follicular cells
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Correct Answer: Option B


Explanation:
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This question belongs to: Science Biology