Classification of Animals
Short Questions and Answers
One Mark Question with Answers
1. Animals living at the bottom of water form
(d) none of these
Answer: (c) benthos
2. Cell aggregate plan is found in
Answer: (a) sponges
3. Blind sac body plan is found in
Answer: (c) coelenterates
4. Annelids possess
(a) cell aggregate plan
(b) blind sac plan
(c) tube within a tube plan
(d) hollow sac plan
Answer: (c) tube within a tube plan
5. Level of organisation in coelenterates is
(d) organ system
Answer: (c) tissue
6. Animals that lay eggs are
(d) none of these
Answer: (a) oviparous
7. Branchial respiration occurs in the
Answer: (c) gills
8. The term for true body cavity in triploblastic animals is
(d) all of these
Answer: (c) coelom
9. Symmetry is biradial in
(d) sea anemone
Answer: (d) sea anemone
10. Excretory organs also bring about
Answer: (a) osmoregulation
11. Which of the following animals is not homoeothermic?
Answer: (c) crocodile
12. Symmetry in vertebrates is
Answer: (c) bilateral
13. Body cavity in arthropods is
(d) all of these
Answer: (b) haemocoel
14. The largest sub kingdom of animal is
Answer: (a) Eumetazoa
15. Coelom is not a schizocoel in
Answer: (c) Echinodermata
Two Marks Questions with Answers
1. What do you mean by zooplanktons?
Answer: The aggregate of passively floating or drifting animals in a body of water is called zooplankton, example, many protozoan protists, small crustaceans (arthropods) and various invertebrate larvae.
2. What do you mean by the term benthos?
Answer: Benthos is a general term originally introduced to describe the those animals found living on the sea bottom but now used to describe organisms of aquatic ecosystems that live associated with a substratum (crawling or burrowing there or attached to rocks) as with sea weeds and sessile animals called benthos, example, starfishes, sea cucumber, sponges, corals etc.
3. What is the difference in a monoecoius and a unisexual organism?
Answer: When both male and female sex organs are found in one individual it is called hermaphrodite or bisexual or monoecious, example, liver fluke, tapeworm, earthworm, leech whereas the animal having only one type of sex organ either male or female but not both is known as unisexual or dioecious, example, frog, lizard, bird, rabbit.
4. How hibernation is different from aestivation?
Answer: Hibernation is the winter sleep. It is observed in frogs, many reptiles and some mammals during winter season while aestivation is summer sleep. It is observed in frogs during too much heat.
5. What is blind sac plan?
Answer: The body has a single cavity with one opening to the outside. The single opening functions as both mouth for ingestion and anus for egestion. The cells are specialized, organised into tissues and show division of labour. It is found in coelenterates and flatworms.
Three Marks Questions with Answers
1. What do you mean by bilateral symmetry?
Answer: In this type of symmetry, the body can be divided into two equal halves by a single plane only because the important body organs are paired and occur on the two sides of a central axis. Bilateral symmetry is found in many invertebrates and all vertebrates.
The right and left sides of the body are called the lateral sides. The side of the body which is kept forward during locomotion is termed as the anterior side and opposite side is called as the posterior side. The back or the upper surface is termed as dorsal and the undersurface towards the substratum is called ventral. The part of a tissue, organ etc that is nearest to the point of attachment or origin is known as proximal end, for example, upper arm is proximal end of the forelimb. The part of a tissue, organ, limb etc that is farther away from the point of attachment or origin is called distal end, example, the fingers are at the distal end of the forelimb.
2. What is radial symmetry?
Answer: In this type of symmetry, a number of similar parts radiate out from a central axis. The body of the individual can be divided into two equal halves the any plane passing through the centre from top to bottom. This type of symmetry is found in some sponges, concenterates (example, Hydra, jellyfish) echinoderms (example star fish). When the body can be divided into two similar halves by one or two vertical planes only the radial symmetry is called biradial symmetry. It is present in the sea anemones. The animals which show radial and biradial symmetry have oral and aboral sides. The oral side is that which has mouth whereas the aboral side is one which is opposite to oral side.
3. What are the different types of body segmentation?
Answer: Segmentation is a type of body form having a linear sequence of units or segments possessing a similar or modified structure. It occurs in three animal phyla- Annelida, Arthropoda and Chordata.
Metameric segmentation (true metamerism or true segmentation)-It is a type of segmentation where external divisions correspond to internal divisions. The bodie is often divided both externally and internally into a number of segments that is metameres example annelids. Segmentation is mostly external in arthropods and mainly internal in man and other chordates ( vertebrae, body muscles, some blood vessels and nerves)
Pseudo metamerism (false segmentation)- It is found in tapeworms. In tapeworms, the proglottides are budded off from the neck, hence this segmentation is called pseudo metamerism (pseudo segmentation). It differs from true segmentations of embryonic origin as found in annelids, arthropods and chordates.
4. What is tube within a tube plan?
Answer: The body has two tubes, one formed by the body wall and a second formed within it by the digestive tract. Digestive tract is a continuous tube like structure that has two openings, a mouth for injestion and anus for egestion. Food is digested and absorbed in the digestive tract. Tube within a tube plan is of two types:
(a) Protostomic- The mouth of the digestive tract develops first in the embryo and anus is formed later. This occurs in roundworms, annelids, molluscs and arthropods.
The animals which have this body plan are called protostomes.
(a) Deuterostomic- The anus of the digestive tract develops first in the embryo and the mouth is formed later. This is seen in the echinoderms and chordates. Thus chordates are evolutionarily closer to the echinoderms than to insects or molluscs. The animals which possess this body plans are called deuterostomes.