Which of the following options does correctly represent the characteristic features of phylum Annelida?
AI-generated explanation. Check against your textbook.
Explanation:
The correct statement is option 2. Annelida are triploblastic animals with bilateral symmetry and a segmented (metamerically arranged) body. They are coelomates, having a true coelom lined by peritoneum. This segmentation is a key feature emphasized in NCERT biology for phylum Annelida. Options 1, 3, and 4 describe incorrect features: 1 says unsegmented, which contradicts the segmented body; 3 mentions an acoelomate and flattened body, not true for annelids; 4 describes diploblastic and radial symmetry, which applies to cnidarians, not annelids. Understanding these contrasts helps reinforce the NCERT characterization of annelids as triploblastic, bilaterally symmetrical, and segmented.
🧠 Did You Know?
Segmentation in annelids allows specialization of body segments for movement and function, a feature highlighted in NCERT discussions of Annelida.
💡 NCERT Memory Line:
“Annelids have a segmented (metamerically arranged) body and are triploblastic with bilateral symmetry.”
Match the following group of organisms with their
respective distinctive characteristics and select the correct option :
Organisms
Characteristics
(A)Platyhelminthes
(I)Cylindrical body with no segmentation
(B)Echinoderms
(II)Warm blooded
animals with direct development
(C)Hemichordates
(III)Bilateral symmetry with incomplete
digestive system
(D)Aves
(IV)Radial symmetry with indirect
development
Choose the correct answer from the options given below:
AI-generated explanation. Check against your textbook.
Explanation:
Matchings as per NCERT:
- Platyhelminthes (A) have bilateral symmetry and are unsegmented with an incomplete digestive system (only one opening). => (III)
- Echinoderms (B) show radial symmetry as adults and have indirect development (larval stage). => (IV)
- Hemichordates (C) are worm-like, unsegmented (cylindrical body, no segmentation) organisms. => (I)
- Aves (D) are warm-blooded and show direct development (hatching resembles the adult). => (II)
Thus the correct pairing is A-III, B-IV, C-I, D-II. The other options mismatch these standard NCERT characteristics.
🧠 Did You Know?
Hemichordates and Echinoderms are considered deuterostomes, like chordates, in embryology.
Bilaterally symmetrical and acoelomate animals
are exemplified by:
AI-generated explanation. Check against your textbook.
Explanation:
The correct option is 2) Platyhelminthes. In NCERT, flatworms are described as bilaterally symmetrical and acoelomates (they lack a true body cavity). This distinguishes them from other groups: Ctenophora are diploblastic with biradial/bilateral tendencies; Aschelminthes (Nemathelminthes) are pseudocoelomates; Annelida are bilateral and eucoelomates.
🧠 Did You Know?
Platyhelminthes are the simplest animals to show bilateral symmetry and to lack a true coelom.
💡 NCERT Memory Line:
Flatworms (Platyhelminthes) are the simplest bilaterally symmetric, acoelomate animals in NCERT.
Which of the following statements are true for
the phylum-Chordata?
(A) In Urochordata notochord extends from head to tail and it is present throughout their life.
(B) In Vertebrata notochord is present during the embryonic period only.
(C) Central nervous system is dorsal and hollow.
(D) Chordata is divided into 3 subphyla : Hemichordata, Tunicata and Cephalochordata.
AI-generated explanation. Check against your textbook.
Explanation:
Correct answer: (B) and (C). In Urochordata (tunicates), the notochord is present only in the larval stage and is not extended throughout life, so statement (A) is false. In Vertebrata, the notochord is present during embryonic development but is typically replaced by the vertebral column, so statement (B) is true. The central nervous system in Chordata is dorsal and hollow (a dorsal nerve cord), so statement (C) is true. Chordata is divided into three subphyla: Cephalochordata, Urochordata (Tunicata), and Vertebrata; Hemichordata is a separate phylum, not a subphylum, so statement (D) is false. Therefore, (B) and (C) are true.
🧠 Did You Know?
The dorsal hollow nerve cord is a key hallmark of Chordata, visible in embryos and some larval stages across subphyla.
💡 NCERT Memory Line:
Notochord is a defining chordate feature; in Vertebrata it is typically replaced by the vertebral column during development.
Consider following features:
(A) Organ system level of organisation
(B) Bilateral symmetry
(C) True coelomates with segmentation of body
Select the correct option of animal groups which
possess all the above characteristics.
AI-generated explanation. Check against your textbook.
Explanation:
The correct option is 2: Annelida, Arthropoda and Chordata. All three groups show organ system level of organisation and bilateral symmetry. They are true coelomates and exhibit body segmentation (Annelida and Arthropoda are clearly segmented;Chordata shows segmentation in its body plan, such as somites in many groups). Thus they possess all the features listed: organ-system level, bilateral symmetry, and true coelomate with segmentation.
🧠 Did You Know?
While Mollusca are bilaterally symmetrical and coelomate with organ systems, they are not typically described as having true body segmentation like Annelids or Arthropods in the NCERT context.
💡 NCERT Memory Line:
Organ system level, bilateral symmetry, and true coelom with segmentation are characteristic of Annelida and Arthropoda; Chordata also shows segmentation in its body plan.