Radial symmetry is not found in adults of phylum

Form and function of external features General features Echinoderms have a Symmetry and body form Many of the earliest echinoderms either lacked symmetry or were bilaterally symmetrical. Bilateral symmetry occurs in all living groups and is especially marked in the larval stages. A tendency toward Pentamerous structure is evident in the arrangement of the tube feet, which usually radiate from the mouth in five bands. Many of the major organ systems, including the water-vascular system, muscles, hemal system (a series of fluid-filled spaces of indeterminate function), and parts of the Distinct The Asteroids have a large central disk from which radiate five or more see below Ophiuroids have a small disk from which five arms radiate. The larger internal organs usually are In echinoids the skeleton forms a rounded, or globular, test of solid plates; tube feet, which emerge through holes in the plates, form five conspicuous bands, or ambulacra. Spaces between bands of feet are called interambulacra. Regular echinoids are roughly spherical in shape, with a centrally located mouth at the junction of the five bands containing tube feet (ambulacra); the anus is located on the side of the body opposite the mouth (aboral). Irregular urchins are Holothurians are elongated, with mouth and anus at opposite ends of the body. The spaces between the tube feet, which are arranged in five rows, or radii, are known as interradii. The tube feet may be more numerous on the underside of the body...

Select the correct statements with reference to chordates. A. Presence of a mid-dorsal, solid and double nerve cord. B. Presence of closed circulatory system. C. Presence of paired pharyngeal gill slits D. Presence of dorsal heart. E. Triploblastic pseudocoelomate animals. Choose the correct answer from the options given below: 1.C, D and E only 2.A, C and D only 3. B and C only 4.B, D and E only Match List - I with List - II List-I List-II (A) Contractile vacuole (I) Asterias (B) Water vascular system (II) Amoeba (C) Canal system (III) Spongilla (D) Flame cells (IV) Taenia Choose the correct answer from the options given below: 1. (A) - (IV), (B) - (II), (C) - (I), (D) - (III) 2.(A) - (I), (B) - (III), (C) - (II), (D) - (IV) 3.(A) - (III), (B) - (II), (C) - (I), (D) - (IV) 4.(A) - (II), (B) - (I), (C) - (III), (D) - (IV) Select the correct statements: (A) Platyhelminthes are triploblastic pseudocoelomate and bilaterally symmetrical organisms. (B) Ctenophores reproduces only sexually and fertilization is external (C) In tapeworm, fertilization is internal by sexes are not separate (D) Ctenophores are exclusively marine, diploblastic and bioluminescent organisms (E) In sponges, fertilization is external and development is direct. Choose the correct answer from the options given below: 1. (A), (C) and (D) only 2. (B), (C) and (D) only 3. (A) and (E) only 4. (B) and (D) only Match List I with List II. List I List II A. Taenia I. Nephridia B. Paramoecium II. Contractile vacuol...

• Radial symmetry refers to the arrangement of parts of organisms around a single axis that can be divided into equal halves across any plane. • This type of symmetry is seen in some sessile aquatic animals. • Animals of the phyla Cnidaria ( Hydra) and Echinodermata (starfish) show radial type of symmetry. • Spider belongs to phylumArthropoda which shows bilateral symmetry. • Thus, the correct answer is option C.

NCERT Exemplar Class 11 Biology Solutions for Chapter 4 Animal Kingdom NCERT Exemplar for Class 11 Biology Chapter 4 The Animal Kingdom is an important study material which helps students to understand the concepts of Animal Kingdom in-depth. Students who are planning to make a career in medical and other biological fields should study the chapter well in order to understand the topics in their higher classes. These exemplar solutions provide questions and answers on Animal Kingdom, which are provided in the NCERT exemplar book, along with quiz questions, entrance questions, MCQs for NEET, exercises and worksheets. The animal kingdom entails all the different animals, which are either multicellular or eukaryotic. Students can learn this topic thoroughly by downloading and practising the exemplar solutions in PDF for free by clicking on the link below. Access NCERT Exemplar Solutions for Class 11 Biology Chapter 4 MULTIPLE CHOICE QUESTIONS 1. In some animal groups, the body is found divided into compartments with a serial repetition of at least some organs. This characteristic feature is called a. Segmentation b. Metamerism c. Metagenesis d. Metamorphosis Solution: Option (b) is the answer. 2. Given below are types of cells present in some animals. Which of the following cells can differentiate to perform different functions? a. Choanocytes b. Interstitial cells c. Gastrodermal cells d. Nematocytes Solution: Option (b) is the answer. 3. Which one of the following sets of an...