134. A water vascular system is characteristic of which phylum?
[MP Forest Guard, 16 June 2023]
(A) Echinodermata
(B) Hemichordata
(C) Arthropoda
(D) Annelida
Answer: (A) Echinodermata
Explanation: Sea stars, sea urchins and related echinoderms use a hydraulic water vascular system. Its tube feet function in movement, food handling and gas exchange, making this structure highly distinctive in animal classification.
133. Which organism belongs to Coelenterata or Cnidaria?
[SSC Stenographer, 12 October 2023]
(A) Aurelia
(B) Spongilla
(C) Euspongia
(D) Sycon
Answer: (A) Aurelia
Explanation: Aurelia is a jellyfish placed within Cnidaria. The other three choices are sponges of Porifera. Cnidarians possess specialised stinging cells called cnidocytes, whereas sponges rely on a porous filtration system.
132. In which animal phylum is the body characteristically divided into head, thorax and abdomen?
[SSC CGL Tier I, 26 July 2023]
(A) Annelida
(B) Mollusca
(C) Arthropoda
(D) Chordata
Answer: (C) Arthropoda
Explanation: Many insects, members of Arthropoda, show three body regions: head, thorax and abdomen. This tagmosis accompanies a chitinous exoskeleton and jointed limbs. Other arthropods may display a cephalothorax and abdomen instead.
131. Which organism is an example of Aschelminthes or Nematoda?
[DDA Junior Engineer, 01 April 2023]
(A) Scorpion
(B) Cockroach
(C) Prawn
(D) Ascaris
Answer: (D) Ascaris
Explanation: Ascaris is a parasitic roundworm belonging to Nematoda, historically termed Aschelminthes. Its unsegmented cylindrical body has a pseudocoelom and complete digestive tract. The remaining organisms are arthropods.
130. Which specialised structures perform excretion in flatworms?
[SSC CGL Tier I, 18 July 2023]
(A) Nerve cells
(B) Flame cells
(C) Ganglia
(D) Hooks
Answer: (B) Flame cells
Explanation: Flatworms possess protonephridial systems whose terminal flame cells help regulate water and eliminate metabolic wastes. The beating cilia within these cells create fluid movement, an important characteristic of platyhelminth excretion.
129. Unsegmented, triploblastic, bilaterally symmetrical acoelomates are mainly classified under which phylum?
[SSC CGL Tier I, 24 July 2023]
(A) Cnidaria
(B) Ctenophora
(C) Platyhelminthes
(D) Porifera
Answer: (C) Platyhelminthes
Explanation: Platyhelminthes exhibit bilateral symmetry, three tissue layers and absence of a true body cavity. This combination differentiates flatworms from diploblastic cnidarians and ctenophores and from cellular-grade sponges.
128. What is generally considered the second-largest invertebrate phylum?
[MPSC Group B, 05 November 2023]
(A) Arthropoda
(B) Porifera
(C) Mollusca
(D) Echinodermata
Answer: (C) Mollusca
Explanation: Among invertebrates, molluscs form one of the most diverse phyla, surpassed in described species by arthropods. Mollusca includes gastropods, bivalves and cephalopods, which share variations of a mantle, visceral mass and muscular foot.
127. Which is a bryophyte?
[SSC CHSL, 15 March 2023]
(A) Cladophora
(B) Marsilea
(C) Marchantia
(D) A monocotyledon
Answer: (C) Marchantia
Explanation: Marchantia is a liverwort and therefore a bryophyte. Cladophora is a green alga; Marsilea is a fern ally belonging to pteridophytes. Bryophytes lack true vascular tissue and depend on water for fertilisation.
126. Which statement about bryophytes is incorrect?
[MP Patwari, 09 April 2023]
(A) They bear flowers
(B) Their spores are generally of one kind
(C) The principal plant body is haploid
(D) The gametophyte is dominant
Answer: (A) They bear flowers
Explanation: Bryophytes are flowerless plants that reproduce by spores. Their conspicuous green phase is the haploid gametophyte, while the sporophyte depends on it. Flowers evolved much later in seed-bearing angiosperms.
125. Moss and Marchantia are examples of which plant group?
[SSC GD Constable, 10 January 2023]
(A) Algae
(B) Gymnosperms
(C) Pteridophytes
(D) Bryophytes
Answer: (D) Bryophytes
Explanation: Mosses and liverworts, including Marchantia, are bryophytes. They reproduce by spores rather than seeds and have a dominant gametophyte. Their sperm require a film of water to reach the egg.
