NCERT Class 11-Biology: Chapter –4 Animal Kingdom

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Question 8:

Differentiate between:

a. Open and closed circulatory system

b. Oviparity and viviparity

c. Direct and indirect development

d. Aceolomate and pseudo coelomate

e. Notochord and nerve cord

f. Polyp and medusa

Answer:

a. The circulatory system may be of two types:

1. Open type in which the blood is pumped out of the heart and the cells and tissues are directly bathed in it. E.g. Arthropoda, Mollusca and Hemichordata.

2. Closed type in which the blood is circulated through a series of vessels of varying diameters (arteries, veins and capillaries). E.g. Annelida and Chordata.

b. Oviparous animals give birth to an egg while viviparous animals are those that give birth to the live young ones.

c. Direct development: It is a type of development in which an embryo develops into a mature individual without involving a larval stage. Indirect development: It is a type of development that involves a sexually-immature larval stage.

d. Acoelomate: The animals in which the body cavity is absent are called acoelomates, e.g. Porifers, Coelentrates, Ctenophores and Platyhelminthes. , Pseudo coelomate: In some animals, the body cavity is not lined by mesoderm, instead, the mesoderm is present as scattered pouches in between the ectodenp and endoderm. E.g., aschelminthes

e. Notochord is a mesodermally derived rod-like-structure formed on the dorsal side during embryonic development in some animals and it is the part of skeletal system. Nerve cord is the part of nervous system.

f. The polyp is a sessile and cylindrical fonn like Hydra, Adamsia, etc., whereas, the medusa is umbrella-shaped and free-swimming like Aurelia or jelly fish.

Question 9:

Give the characteristic features of the following citing one example of each

a. Chondrichthyes and ostichthyes

b. Urochordata and cephalochordate

Answer:

a. Chondrichthyes - They are marine animals with streamlined body and have cartilaginous endoskeleton. Mouth is located ventrally. Notochord is persistent throughout life. Gill slits are separate and without operculum (gill cover). The skin is tough, containing minute placoid scales. Teeth are modified placoid scales which are backwardly directed. Their jaws are very powerful. These animals are predaceous. Due to the absence of air bladder, they have to swim constantly to avoid sinking. Scoliodon (Dog fish), Pristis (Saw fish), Carcharodon (Great white shark), Trygon (Sting ray).

Osteichthyes: It includes both marine and fresh water fishes with bony endoskeleton. Their body is streamlined. Mouth is mostly terminal. They have four pairs of gills which are covered by an operculum on each side. Skin is covered with cycloid/ctenoid scales. Air bladder is present which regulates buoyancy.

Examples: Marine—Exocoetus (Flying fish), Hippocampus (Sea horse); Freshwater-Labeo (Rohu), Catla (Katla), Clarias (Magur); Aquarium-Betta (Fighting fish), Pterophyllum (Angel fish),

b. Subphyla Urochordata and Cephalochordata are often referred to as protochordates and are exclusively marine. In Urochordata, notochord is present only in larval tail, while in Cephalochordata, it extends from head to tail region and is persistent throughout their life.

Examples: Urochordata-Ascidia, Salpa, Doliolum; Cephalochordata- Branchiostoma (Amphioxus or Lancelet).

Question 10:

Mention two similarities between

a. Aves and mammals

b. A frog and crocodile

c. A turtle and pila

Answer:

(a) Both of them are worm blooded animals and they have four-chambered heart.

(b) Both of them can live on land as well as in water. Both of them breathe through lungs.

(c) Their body is covered with a hard shell. Both are oviparous animals.

Question 11:

Name

a. A limbless animal

b. A cold blooded animal

c. A warm blooded animal

d. An animal possessing dry and cornified skin

e. An animal having canal system and spicules

f. An animal with cnidoblasts

Answer:

(a) Ichtyophis

(b) Frog

(c) Parrot

(d) Python

(e) Sycon

(f) Obelia

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