Which of the following is a correct statement about sponges (phylum Porifera)?
A. They are multicellular with a cellular level of organization.
B. They have a well-developed nervous system.
C. They have tissues and organs.
D. They are exclusively terrestrial.
Answer: Option A
Solution (By JKExamLibrary)
Sponges are the simplest multicellular animals with a cellular level of organization (no true tissues or organs). They are mostly marine, sessile, filter feeders. Water enters through numerous pores (ostia) into a spongocoel and exits through the osculum. They lack a nervous system. They possess specialized cells like choanocytes and amoebocytes but no coordination.
Explanation:
Aqueous humor is a clear fluid in the anterior and posterior chambers of the eye, providing nutrients and maintaining intraocular pressure. Vitreous humor is the gel in the posterior segment.
Explanation:
Robert Brown, a Scottish botanist, first described the nucleus in 1831 while studying epidermal cells of orchids. Hooke discovered cells, Leeuwenhoek observed living cells, Virchow proposed that cells arise from pre-existing cells. Brown's discovery was pivotal for understanding cellular organization.
Explanation:
Lymphatic filariasis, caused by Wuchereria bancrofti and transmitted by Culex mosquito, leads to chronic swelling of limbs (elephantiasis) due to blockage of lymphatic vessels. Amoebiasis is Entamoeba, sleeping sickness Trypanosoma, kala-azar Leishmania.
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