Chapter 4 Animal Kingdom Solutions
Question - 1 : - What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?
Answer - 1 : -
If fundamental characters are not taken into account then the classification of animals is difficult due to difference in characters in different animals which are as following:
(i) Grade of organisation
(ii) Symmetry
(iii) Coelom
(iv) Segmentation
(v) Notochord
Common fundamental features help in grouping animals in certain categories or sub-categories. For examples, all birds have fore-limbs modified to assist in flying. This gives us one clue to categorise a particular animals among aves.
Question - 2 : - If you are given a specimen, what are the steps that you would follow to classify it?
Answer - 2 : -
Classification of specimen deals according to a systematic plan on the basis of their v similarities, differences and relationship.
We will take following steps
(i) Level or grade of organisation:
There are different types of cell which are organised into functional units of progressively increasing complexity. Such as acellular, cellular, tissue, organ and organ system.
(ii) Pattern in organ system :
Threre are different organ system in which specific group of organs work together to do a specific function. Such as digestive organs in digestive system. Respiratory organs in respiratory system, etc. in animal body.
(iii) Symmetry:
In animals, 4-types of symmetry are seen. These are spherical, radial, bilateral, Assymetrical species are classified according to symmetry.
(iv) Diploblastic and triploblastic organisation: According to number of germ layers which differentiate at the time of gastrulation in developing embryo. Species are classified as diploblastic i.e. two germ layer and Triploblastic i.e. three germlayers.
(v) Body cavity or coelom :
According to types of coelom, species are classified into acoelom, pseudocoelom and eucoelom animals.
(vi) Segmentation:
Species are classified according to segmentation. It is of three types i.e. pseudometamerism or false segmentation, internal and external segmentation.
(vii) Notochord:
On the basis of notochord, animals or species are divided into chordates and non- chordates.
We will follow the above steps in classification of animal, then fair idea of that animal can be derived.
Question - 3 : - How useful is the study of the nature of body cavity and coelom in the classification of animals?
Answer - 3 : -
Coelom is the gap between gut and body wall. Coelom is the characterstic feature of complex or higher animals while lower animals like platyheminthes are acoelomate. The absence of coelom indicates that the animal is yet to develop a functional division of labour to carry out various activities. So the coelom characterises complexity of the animals and represents organic evolution.
There are three types of coelom
(i) Acoelom – It means absence of body cavity which is due to the failure of mesoderm to cavitate during embryogency, so there is no coelom, no peritonium. ex-porifera, colenterata, etc.
(ii) Pseudocoelom — It means presence of coelom that develops from the blastocoel but not lined by mesoderm, ex-nematodes, etc.
(iii) Eucoelom – It means hue coelom, which is lined by mesoderm resulting in tube within -tube design.
ex- higher invertebrates, chordates, etc.
Question - 4 : - Distinguish between intracellular and extracellular digestion?
Answer - 4 : -
- Intracellular digestion takes place inside the cells by cellular enzymes, which are secreted by the surrounding cytoplasm into the food vacuole and the digestive products are then diffused in cytoplasm.
- It mainly occurs in unicellular organism and also is a less efficient method.
- Extracellular digestion occurs with the help of digestive enzymes poured into gastrovascular cavity by secretory cells and then the digestive products are diffused across the intestinal wall into various parts of the body.
- It mainly occurs in multicellular organisms and is more efficient.
Question - 5 : - What is the difference between direct and indirect development?
Answer - 5 : -
In direct development young ones are formed directly from development of zygote whereas young ones are formed through an intermediate stage i.e. larval stage in the indirect development. There is no intermediate stage, indirect development and young one resembles the adult.
Question - 6 : - What are the peculiar features that you find in parasitic platyhelminthes?
Answer - 6 : -
Members of platyhelminthes possess following characteristics.
(i) These are mostly endoparasites of animals including human.
(ii) Hook and suckers are present for attachment to host body.
(iii) They absorb nutrient from the host directly through their body surface.
(iv) These are free living, parasitic forms. Tissue, organ, grade of body organization is seen.
(v) Digestive tract is incomplete or absent.
(vi) Respiration is anaerobic.
(vii) Reproductive system of parasitic forms is highly developed with enormous power of reproduction.
(viii) Well defined excretory organs such as flame cells are present.
Question - 7 : - What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Answer - 7 : -
Arthropods are the most successful group of animals on the earth. Their success is due to
(i) Unique chitinous cuticle
(ii) Light weight exoskeleton
(iii) Omnivorous habit
(iv) Mouth parts adapted to various mode of feeding like biting, chewing, sucking etc.
(v) Adaptation to different climatic conditions
Question - 8 : - Water vascular system is the characteristic of which group of the following:
(a) Porifera
(b) Ctenophora
(c) Echinodermata
(d) Chordata
Answer - 8 : -
Echinodermata – Its vascular system with tube feet helps in locomotion. A perforated plate , madreporite, permits entry of water into ambulacral system which also help in food and gas transport system.
Question - 9 : - “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.
Answer - 9 : -
Phylum chordates includes two subphyla
(i) Protochordates (urochordates and cephalochordates) or Acraniata
(ii) Vertebrates or Craniata
All chordates have notochord present in some stage of life. In vertebrates the notochord is present in the embryonic stage. This is replaced by a vertebral column during the adult stages.
This confirms that all vertebrates are chordates but all chordates are not vertebrates, they may be protochordate.
Question - 10 : - Ho w important is the presence of air bladder in Pisces?
Answer - 10 : -
Air bladder is a hydrostatic organ which regulates buoyancy. It also aids in swimming by reducing the weight of body. Hence, this means that members of Pisces don’t have to keep on swimming to remain floating.