The organism that causes citrus canker is: MCQ with Answer and Explanation

The organism that causes citrus canker is:
A. Mycoplasma
B. Virus
C. Bacterium
D. Fungus
Answer: Option C
Solution (By JKExamLibrary)
Citrus canker is a bacterial disease caused by Xanthomonas citri (syn. X. axonopodis pv. citri). It produces raised necrotic lesions on leaves, fruit, and stems, causing defoliation and reduced yield. It spreads via rain splash and contaminated tools. No viral or fungal causal agent.

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Practice More Biology Questions

Question #1
The mineral that is a component of the hormone insulin is:
A. Calcium
B. Zinc
C. Sulfur
D. Iron

Correct Answer: Option B


Explanation:
Zinc is a component of the insulin hexamer stored in pancreatic beta cells; it stabilizes the insulin structure. Iron is in hemoglobin, calcium in bones/signaling, sulfur in some amino acids. Zinc deficiency impairs insulin secretion. Many enzymes require zinc as a cofactor.

This question belongs to: Science Biology
Question #2
Charles Darwin proposed the theory of evolution by:
A. Use and disuse of organs
B. Inheritance of acquired characters
C. Mutation theory
D. Natural selection

Correct Answer: Option D


Explanation:
Charles Darwin, an English naturalist, proposed the theory of evolution by natural selection in his seminal book 'On the Origin of Species' (1859). His theory, based on observations from his voyage on the HMS Beagle (especially the Galapagos finches), states that species evolve over time through the process of natural selection, where individuals with advantageous traits are more likely to survive and reproduce.

This question belongs to: Science Biology
Question #3
The process of taking in solid particles by a cell is called:
A. Pinocytosis
B. Phagocytosis
C. Osmosis
D. Exocytosis

Correct Answer: Option B


Explanation:
Phagocytosis ('cell eating') is the engulfment of large particles or microbes by the cell membrane forming a phagosome. Pinocytosis is 'cell drinking' of liquids. Exocytosis is secretion.

This question belongs to: Science Biology