Which of the following diseases is caused by the protozoan Plasmodium vivax?
A. Amoebic dysentery
B. Giardiasis
C. Malaria
D. Sleeping sickness
Answer: Option C
Solution (By JKSSB Mock Tests)
Malaria is caused by Plasmodium species (P. vivax, P. falciparum, etc.) and transmitted by female Anopheles mosquitoes. P. vivax causes benign tertian malaria with 48-hour fever cycles. Amoebic dysentery is caused by Entamoeba histolytica, sleeping sickness by Trypanosoma, and giardiasis by Giardia. Malaria remains a major global health challenge.
Explanation:
Phloem transports organic solutes (mainly sucrose) from source (leaves) to sink (roots, fruits) in a process called translocation, using sieve tubes and companion cells. Xylem transports water and minerals from roots upwards. Collenchyma and sclerenchyma are mechanical tissues providing support. Phloem is alive at maturity, while xylem vessels are dead. Companion cells regulate sieve tube activity.
Explanation:
Oxytocin from the posterior pituitary causes myoepithelial cells around mammary alveoli to contract, ejecting milk. Prolactin stimulates milk synthesis.
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