Austin Study Centre : 11th zoology Chapter2

22. Why are spongin and spicules important to a sponge?
The body is supported by a skeleton made of spicules or spongin or both.
The spicules are made up of calcium and silica.

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23. What are the four characteristics common to most animals?

1) Cellular structure

2) The nature of coelom

3) Notochord

4) Segmentation or absence of segmentation

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24. List the features that all vertebrates show at some point in their development

1) Embryonic germ layer a) Endoderm, b) Ectoderm - Two germinal layers.

2) a) Ectoderm, b) Endoderm, c) Mesoderm - Three germinal layers

3) Organogenesis

i) Ectoderm - Skin, Hair, Nerve, Tooth, Nail

ii) Endoderm-Intestine lung, Liver

iii) Mesoderm - Muscle, Bones, Heart

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25. Compare closed and opened circulatory system

Open Circulation

i. There is no blood vessels

2. Blood remains filled in the tissue spaces.

3. (Eg.) Arthropods, Mollusca, Echinodermata.

Closed Circulation

i. Presence of blood vessels.

ii. Blood is circulated through blood vessels.

iii. (Eg.) Earthworm, Cephalochordates, Chordates

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26.Compare Schizocoelom with enterocoelom

Schizocoelomates
Body cavity is formed by spilitting of mesoderm.
(Eg.) Annelids, Arrthopods
Enterocoelomates
The body cavity is formed from the Mesodermal pouches or archenteron.
(Eg.) Echinodermata Chordates
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27. Identify the structure that the archenteron becomes in a developing animal.

The archenteron becomes the digestive tract (or primitive gut) of the developing animal. Formed during the gastrulation stage of embryonic development, this hollow pouch eventually develops into the stomach, intestines, and other components of the gastrointestinal system

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28. Observe the animal below and answer the following questions

a. Identify the animal.

b. What type of symmetry does this animal exhibit?

c. Is this animal Cephalized?

d. How many germ layers does this animal have?

e. How many openings does this animal’s digestive system have?

f. Does this animal have neurons?

a) Sea anemone

b) Radial symmetry

c) It is not a cephalized animal

d) Diploblastic animal

e) One

f)Yes

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29. Choose the term that does not belong in the following group and explain why it does not belong?
Notochord, cephalisation, dorsal nerve cord and radial symmetry
Unrelated characters: Radial Symmetry
1) Notochord, Cephalization dorsal nerve chord, are characteristic features of chordate animals.
Radial Symmetry
This is the feature of invertebrate organism.
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30. Why flatworms are called acoelomates?

Flatworms are called acoelomates because they completely lack a coelom—a fluid-filled, mesoderm-lined body cavity between the digestive tract and the outer body wall.

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31. What are flame cells?

Specialized excretory cells present in flatworms called flame cell helps in Osmoregulation and excretion

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32. Concept Mapping - Use the following terms to create a concept map that shows the major characteristic features of the phylum nematoda:

Round worms, pseudocoelomates, digestive tract, cuticle, parasite, sexual dimorphism

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33. In which phyla is the larva trochopore found?

Trochopore larva is seen in the Phylum - Annelida.

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34. Which of the chordate characteristics do tunicates retain as adults?

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35. List the characteristic features that distinguish cartilaginous fishes with living jawless fishes

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36. List three features that characterize bony fishes.

1) The body is spindle shaped skin is covered by ganoid cycloid or Ctenoid scales.

2) They have four pairs of filamentous gills with operculam on either side.

3) Air bladder helps in gaseous exchange and for maintaining buoyancy.

4) Sexes are separate.

5) They have lateral line sense organs. The kidney is mesonephric.

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37. List the functions of air bladder in fishes.

The air bladder (or swim bladder) in bony fishes is primarily a gas-filled hydrostatic organ that helps fish maintain neutral buoyancy. By adjusting the gas volume within this organ, fish can effortlessly float, sink, or hover at a specific depth without wasting energy

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38. Write the characteristics that contributes to the success of reptiles on land.

1) The body of reptile is covered by dry and cornified skin with epidermal scales or scutes.

2) All are poikilotherms.

3) Most reptiles lay cleidoic eggs.

4) Excretion is by metanephric kidneys and are uricotelic.

5) Internal fertilization is taking place

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39. List the unique features of bird’s endoskeleton.

1) The endoskeleton is fully ossified.

2) The long bones are hollow with air cavities. So that they can easily fly with lesser weight.

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40. Could the number of eggs or young ones produced by an oviparous and viviparous female be equal? Why?

No, the number of eggs or young ones produced by an oviparous and viviparous mother cannot be equal. The number of eggs laid by the oviparous animals are always more in number than the young ones produced by viviparous animals.

Viviparous animals: Viviparous animals are those animals in which both the fertilization (i.e. the fusion of male and female gametes) of egg that results in zygote and development of embryo take place inside the body of the female in the mother's womb.These animals give birth to young ones directly.Examples – mammals such as cows, goats, dogs, humans, etc.

Oviparous animals: Oviparous animals are those animals in which both the process of development of embryos take place outside the body of the female.In oviparous animals fertilization can occur inside the mother’s body or outside the mother’s body.Oviparous animals lay eggs outside their body. Example – birds, hen, frogs, etc

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