Maharashtra Board Class 11 Biology Chapter 4 Kingdom Animalia Solutions

Balbharti Maharashtra State Board 11th Biology Textbook Solutions Chapter 4 Kingdom Animalia Textbook Exercise Questions and Answers.

Kingdom Animalia Class 11 Exercise Question Answers Solutions Maharashtra Board

Class 11 Biology Chapter 4 Exercise Solutions Maharashtra Board

Biology Class 11 Chapter 4 Exercise Solutions

1. Choose Correct Option

Question (A)
Which of the following belongs to a minor phylum?
(a) Comb jelly
(b) Jelly fish
(c) Herdmania
(d) Salpa
Answer: (a) Comb jelly
In simple words: Comb jellies, or Ctenophores, are often considered a minor phylum due to their smaller number of species compared to major phyla like Arthropoda or Mollusca.

🎯 Exam Tip: Pay attention to the distinguishing characteristics of minor phyla, as they are often tested for their unique features.

Question (B)
Select the animal having venous heart.
(a) Crocodile
(b) Salamander
(c) Rohu
(d) Toad
Answer: (c) Rohu
In simple words: Rohu, being a fish, possesses a two-chambered heart that only pumps deoxygenated blood to the gills for oxygenation, hence it's called a venous heart.

🎯 Exam Tip: Remember that "venous heart" specifically refers to a heart that pumps only deoxygenated blood, a characteristic feature of fish circulatory systems.

Question (C)
In Ascaris, –––––––––.
(a) mesoglea is present
(b) endoderm is a discontinuous layer
(c) mesoderm is present in patches
(d) body cavity is absent
Answer: (c) mesoderm is present in patches
In simple words: Ascaris, being a pseudocoelomate, has its mesoderm scattered in patches between the ectoderm and endoderm, forming a false body cavity.

🎯 Exam Tip: Differentiate clearly between acoelomates, pseudocoelomates, and coelomates based on the presence and arrangement of mesoderm and body cavity.

Question (D)
Which of the following is INCORRECT in case of birds?
(a) Presence of teeth
(b) Presence of scales
(c) Nucleated RBCs
(d) Hollow bones
Answer: (a) Presence of teeth
In simple words: Birds lack teeth, using a gizzard for grinding food, making the statement about the presence of teeth incorrect for them.

🎯 Exam Tip: Focus on unique adaptations of birds for flight, such as hollow bones and the absence of teeth, which reduce overall body weight.

Question (E)
Chitinous exoskeleton is a characteristic of –––––––––.
(a) Dentalium
(b) Antedon
(c) Millipede
(d) Sea urchin
Answer: (c) Millipede
In simple words: Millipedes are arthropods, and a defining feature of arthropods is their tough, protective exoskeleton made of chitin.

🎯 Exam Tip: Remember that chitin is a key component of the exoskeleton in arthropods, providing structural support and protection.

2. Answer The Following Questions.

Question (A)
Reptiles are known for having three chambered heart. Which animal shows a near four chambered condition in reptiles?
Answer:
Crocodiles have a four chambered heart.
In simple words: Among reptiles, crocodiles are unique in possessing a nearly four-chambered heart, distinguishing them from most other reptiles with three-chambered hearts.

🎯 Exam Tip: Crocodiles are an important exception to remember regarding heart structure in reptiles due to their more developed circulation.

Question (B)
The circulatory system has evolved from open to closed type in Animal Kingdom. Which Phylum can be called first to represent closed circulation?
Answer:
Phylum Annelida is the first phylum to represent closed circulation.
In simple words: Annelids, like earthworms, were the first to evolve a closed circulatory system where blood is confined within vessels, allowing for more efficient transport.

🎯 Exam Tip: Understanding the evolutionary progression of circulatory systems, from open to closed, helps in classifying phyla and understanding their complexity.

Question (C)
Pinna is part of external ear and it is found in mammals. Do Aves and Reptiles show external ear in any form?
Answer:
No, Aves and Reptiles do not show external ear in any form. They possess tympanum which represents the ear.
In simple words: Aves and Reptiles do not have external ear flaps (pinna) like mammals; instead, they have a tympanum (eardrum) that is typically exposed or covered by feathers/scales.

🎯 Exam Tip: Distinguish between the presence of a pinna (external ear flap), which is characteristic of mammals, and a tympanum, which is present in many other vertebrates.

Question (D)
Fish and frog can respire in water. Can they respire through their skin? If yes, why do they have gills?
Answer:
1. Yes, fishes and frogs can respire through their skin.
2. The larval stage of frog i. e. tadpole respires through gills. During metamorphosis, tadpoles lose their gills and develop lungs.
3. Frogs do not have scales and breathe through their skin underwater.
4. Fishes respire primarily via gills. The body of fishes is covered with scales which limits cutaneous respiration in them.
In simple words: While some fishes and frogs can respire cutaneously (through skin), gills are the primary respiratory organs for fishes in water, and for larval frogs (tadpoles), because gills are highly efficient for extracting oxygen from water.

🎯 Exam Tip: Note the different respiratory adaptations across aquatic vertebrates; frogs show a transition with gills in larvae and skin/lungs in adults, while fish primarily rely on gills.

Question (E)
Birds need to keep their body light to help in flying. Hence, they show presence of some organs only on one side. How their skeleton helps in reducing their weight?
Answer:
1. In birds, the forelimbs are modified into wings for flying.
2. They possess stream-lined body to reduce resistance during flight.
3. Bones are hollow or pneumatic to reduce body weight.
4. In order to reduce body weight, urinary bladder is absent. Also, females possess only left ovary and oviduct.
5. Body is covered by feathers to facilitate flying.
In simple words: Birds reduce body weight for flight by having hollow, pneumatic bones, modifying forelimbs into wings, having a streamlined body, and lacking a urinary bladder, with females often having only one functional ovary.

🎯 Exam Tip: Focus on the specific structural and physiological adaptations in birds that contribute to a reduced body weight, which is crucial for efficient flight.

Question (F)
Cnidarians and Ctenophorans are both diploblastic. Which other character do they have in common, which is not found in other phyla?
Answer:
Cnidarians and ctenophorans show tissue level of body organization. They have blind sac body plan and radially symmetrical body.
In simple words: Besides being diploblastic, Cnidarians and Ctenophorans share tissue-level organization, a blind-sac body plan (single opening for food intake and waste expulsion), and radial symmetry.

🎯 Exam Tip: When comparing phyla, identify key shared characteristics like germ layers, body plan, and symmetry, as these are fundamental classification criteria.

Question (G)
Crab and Snail both have a protective covering. Is it made up of the same material?
Answer:
No, the protective covering is not made up of same material in crab and snail. The protective covering of crabs is made up of chitin and that of snails is made up of calcium carbonate.
In simple words: Crabs have a chitinous exoskeleton, while snails have a shell made of calcium carbonate; thus, their protective coverings are composed of different materials.

🎯 Exam Tip: Understand that protective coverings in different phyla can have varied chemical compositions, reflecting distinct evolutionary paths and material availability.

Question (H)
Sponge and sea star show calcareous protective material. Do they belong to the same Phylum?
Answer:
No, they do not belong to same phylum. Sponges belong to phylum Porifera and sea star belongs to phylum Echinodermata.
1. Adult echinoderms are radially symmetrical but larval forms are bilaterally symmetrical.
2. Larvae of echinoderms are free-swimming.
In simple words: Despite both having calcareous protective materials, sponges belong to Phylum Porifera, while sea stars are Echinoderms; they are distinctly different phyla.

🎯 Exam Tip: Do not group organisms solely based on the presence of similar materials; always consider their overall body plan, symmetry, and developmental stages for accurate classification.

Question (I)
Fish and snake both have scales. How do these scales differ from each other?
Answer:
Fishes have dermal scales covering the body surface whereas snakes have epidermal scales or scutes.
In simple words: Fish scales are dermal, originating from the dermis, while snake scales are epidermal, originating from the epidermis, showing different developmental origins.

🎯 Exam Tip: Differentiating between dermal (fish) and epidermal (reptile) scales is crucial as it highlights differences in their embryonic origin and structural composition.

Question (J)
Lower Phyla like Arthropods and Cnidarians show metamorphosis. Is it also found in any class of Phylum Chordata?
Answer:
Yes, it is also found in class Amphibia of phylum Chordata.
In simple words: Metamorphosis, common in lower phyla, is also notably present in the class Amphibia of Phylum Chordata, such as in frogs transitioning from tadpoles to adults.

🎯 Exam Tip: Recognize metamorphosis as a developmental process that occurs across various animal phyla, including amphibians within Chordata, and not just in invertebrates.

Question 3.
Draw neat labelled diagram.
A. Sycon
B. Aurelia
C. Amphioxus
D. Catla
E. Balanoglossus
F. Scolidon
Answer:

ℹ️ चित्र व्याख्या (Diagram Explanation): यह डायग्राम 'साइकोन' नामक एक स्पंज की संरचना को दर्शाता है, जिसमें ऑस्कुलम (बड़ा छिद्र), ऑस्टिया (छोटे छिद्र), कोएनोसाइट (कॉलर कोशिकाएं), एंकोपाइल और एक सामान्य आधार जैसे मुख्य भाग स्पष्ट रूप से लेबल किए गए हैं। यह एक पोरिफेरा सदस्य की आंतरिक और बाहरी विशेषताओं को प्रस्तुत करता है।
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र 'ऑरिलिया' (जेलीफिश) की संरचना का वर्णन करता है, जिसमें छाता जैसी ऊपरी सतह (अम्ब्रेल्लार सरफेस), मार्जिनल लैपेट (किनारे के लोब), उप-छाता सतह (सब अम्ब्रेल्लार सरफेस), मुखीय भुजाएं (ओरल आर्म) और मार्जिनल टेंटेकल्स (किनारे के स्पर्शक) जैसे विभिन्न लेबल किए गए भाग शामिल हैं। यह एक समुद्री जीव की विशिष्ट शारीरिक रूपरेखा को दर्शाता है।
ℹ️ चित्र व्याख्या (Diagram Explanation): यह डायग्राम 'एम्फियोक्सस' नामक एक सेफेलोकोर्डेट की आंतरिक संरचना को दिखाता है, जिसमें फेरिनक्स, वेस्टिब्यूल, बुक्कल सिर्री, गिल स्लिट्स, नोटोकॉर्ड, डोर्सल हॉलो नर्व कॉर्ड, मिडगट डाइवर्टिकुलुम, एट्रियोपोर, मायोटोम्स, गुदा (एनस) और कॉडल फिन जैसे महत्वपूर्ण अंग स्पष्ट रूप से लेबल किए गए हैं। यह कॉर्डेट्स की मूलभूत विशेषताओं को प्रस्तुत करता है।
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र 'कटला' मछली की बाहरी संरचना को दर्शाता है, जिसमें डॉर्सल फिन, ऑपरकुलम (गिल कवर), आंख (आई), मुंह (माउथ), पेक्टोरल फिन, वेंट्रल फिन, पेल्विक फिन और काँटेदार पूंछ (फोर्केड टेल) जैसे विभिन्न लेबल किए गए भाग शामिल हैं। यह एक सामान्य मछली की शारीरिक विशेषताओं को स्पष्ट करता है।
ℹ️ चित्र व्याख्या (Diagram Explanation): यह डायग्राम 'बालानोग्लोसस' नामक एक हेमीकॉर्डेट की शरीर संरचना को दर्शाता है, जिसमें प्रोबोसिस (शुंड), कॉलर, ब्रांकियल क्षेत्र, जननांग क्षेत्र, यकृत क्षेत्र और गुदा (एनस) जैसे मुख्य भाग स्पष्ट रूप से लेबल किए गए हैं। यह इस अद्वितीय समुद्री जीव की शारीरिक खंडों को प्रस्तुत करता है।
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र 'स्कॉलिओडॉन' (डॉगफिश) की बाहरी संरचना का वर्णन करता है, जिसमें डॉर्सल फिन, आंख (आई), मुंह (माउथ), गिल क्लेफ्ट्स, पेल्विक फिन, मीडियन वेंट्रल फिन और कॉडल फिन जैसे विभिन्न लेबल किए गए भाग शामिल हैं। यह एक कार्टिलेजिनस मछली की विशिष्ट शारीरिक रूपरेखा को दर्शाता है।
In simple words: The question asks for labeled diagrams of various animals from different phyla, including Sycon (sponge), Aurelia (jellyfish), Amphioxus (cephalochordate), Catla (fish), Balanoglossus (hemichordate), and Scoliodon (shark), illustrating their key morphological features.

🎯 Exam Tip: Practice drawing and labeling key diagrams of representative animals from each phylum, as these are frequently asked in examinations to assess anatomical knowledge.

Question 4.
Match the following.

Phylum	Characters
1. Annelida	(a) Tube feet
2. Mollusca	(b) Ostia
3. Ctenophora	(c) Radula
4. Porifera	(d) Parapodia
5. Echinodermata	(e) Comb plates

Answer:

Phylum	Characters
1. Annelida	(d) Parapodia
2. Mollusca	(c) Radula
3. Ctenophora	(e) Comb plates
4. Porifera	(b) Ostia
5. Echinodermata	(a) Tube feet

In simple words: This matching exercise connects different animal phyla with their characteristic features, such as Parapodia for Annelida, Radula for Mollusca, Comb plates for Ctenophora, Ostia for Porifera, and Tube feet for Echinodermata.

🎯 Exam Tip: Memorize the unique distinguishing characteristics of each phylum, as matching questions are a common way to test knowledge of animal classification.

5. Identify The Animals Given In Pictures And Write Features Of Its Phylum/Class.

Question 1.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक कंघी जेली (कॉम्ब जेली) को दर्शाता है, जिसमें शरीर का लाल रंग और पानी में तैरने की स्पष्ट बनावट है। यह सिलिया की पंक्तियों के साथ एक छोटा, पारदर्शी समुद्री जीव है जिसका उपयोग गति और शिकार पकड़ने के लिए किया जाता है, जो इसे फाइलम सीटेनोफोरा से संबंधित करता है।
Answer:
The organism in the given picture is Comb jelly (Red midwater Comb jelly) and it belongs to phylum Ctenophora.
In simple words: The image displays a Comb jelly, belonging to the phylum Ctenophora, characterized by bioluminescence and ciliated comb plates for locomotion.

🎯 Exam Tip: When identifying organisms from images, look for distinctive morphological features (e.g., comb plates for Ctenophora) that are characteristic of their phylum or class.

Question 2.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक ईल को दर्शाता है, जिसमें एक लंबा, सर्पीला शरीर और चिकनी त्वचा होती है जो इसकी जलीय जीवन शैली के अनुकूल होती है। इसकी शारीरिक संरचना मछली जैसी है लेकिन यह बिना पंखों के सांप जैसी दिखती है, जो इसे फाइलम कॉर्डेटा से संबंधित करती है।
Answer:
The organism in the given picture is Eel and it belongs to phylum Chordata.
In simple words: The picture shows an Eel, which is a fish and therefore belongs to the phylum Chordata.

🎯 Exam Tip: Even if an animal looks unusual, remember to categorize it based on fundamental chordate characteristics like the presence of a notochord, dorsal hollow nerve cord, pharyngeal gill slits, and post-anal tail at some stage of development.

Question 3.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक डॉल्फ़िन को दर्शाता है, जिसमें एक चिकना, सुव्यवस्थित शरीर और स्पष्ट फिन हैं जो समुद्री वातावरण में गति के लिए अनुकूलित हैं। इसका रंग आमतौर पर ग्रे होता है, और यह एक स्तनपायी की पहचान योग्य विशेषताओं को प्रदर्शित करता है, जो इसे वर्ग स्तनधारी (Mammalia) से संबंधित करती है।
Answer:
The given organism in the given picture is Dolphin and it belongs to class Mammalia.
In simple words: The organism in the image is a Dolphin, which is classified under the class Mammalia due to characteristics like mammary glands, live birth, and warm-bloodedness.

🎯 Exam Tip: Recognize key features of mammals, such as the presence of mammary glands, hair/fur, and typically viviparous reproduction, even for aquatic forms like dolphins.

Question 4.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक सांप को दर्शाता है, जिसमें विशिष्ट तराजू (स्केल) पैटर्न के साथ एक लंबा, बिना पैर वाला शरीर होता है। इसका शरीर मुड़ा हुआ और घुमावदार है, जो इसकी भूमि पर रेंगने की गति को दर्शाता है, जो इसे वर्ग रेप्टिलिया से संबंधित करता है।
Answer:
The given organism is Snake and it belongs to class Reptilia
In simple words: The image features a Snake, which falls under the class Reptilia, characterized by scales and being cold-blooded.

🎯 Exam Tip: Identify reptiles by their scaly skin, cold-blooded nature, and often, the absence of limbs, which are adaptations for terrestrial life.

Question 5.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक समुद्री अर्चिन को दर्शाता है, जिसमें कठोर, गोल शरीर होता है जो तेज स्पाइक्स (कांटों) से ढका होता है। इसकी सतह पर छोटे ट्यूबलर फीट भी होते हैं, जो इसे फाइलम एकाइनोडर्मेटा से संबंधित करते हैं, जो इसकी समुद्री और रेडियल समरूपता को दर्शाते हैं।
Answer:
The given organism is Sea urchin and belongs to phylum Echinodermata.
In simple words: The picture shows a Sea urchin, an Echinoderm known for its spiny skin and radial symmetry.

🎯 Exam Tip: Look for radial symmetry and a spiny body surface as key indicators of organisms belonging to the phylum Echinodermata.

Question 6.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र एक उड़ने वाली छिपकली को दर्शाता है, जिसके शरीर के किनारों पर पंख जैसी झिल्ली होती है जो उसे ग्लाइड करने की अनुमति देती है। इसका शरीर आमतौर पर पतला होता है, और यह वर्ग रेप्टिलिया से संबंधित कई छिपकलियों के विशिष्ट आकार और बनावट को प्रदर्शित करता है।
Answer:
The given organism is flying lizard and belongs to class Reptilia.
In simple words: The image shows a flying lizard (Draco), a reptile adapted for gliding using skin flaps, thus belonging to class Reptilia.

🎯 Exam Tip: Note that "flying" in this context refers to gliding, not active flight with wings, and that this unique adaptation still places the animal within the reptile class.

Question 7.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र 'हर्डमानिया' नामक एक यूरोकॉर्डेट को दर्शाता है, जिसमें एक अस्पष्ट, थैली जैसा शरीर होता है जो अक्सर समुद्री तल से जुड़ा होता है। इसकी संरचना एक समुद्री स्क्वर्ट के समान है, जो इसकी निस्पंदन-भोजन की जीवन शैली और फाइलम कॉर्डेटा के उप-फाइलम यूरोकॉर्डेटा से संबंधित होने का सुझाव देती है।
Answer:
The organism is Herdmania and belongs to Phylum Chordata (Subphylum Urochordata).
In simple words: The organism depicted is Herdmania, a tunicate that is a member of the Urochordata subphylum, and thus part of the larger Phylum Chordata.

🎯 Exam Tip: Remember that Urochordates (like Herdmania) exhibit chordate characteristics primarily in their larval stage, which is a crucial detail for their classification.

Question 8.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र 'नॉटिलस' नामक एक समुद्री जीव को दर्शाता है, जिसमें एक विशिष्ट, सर्पिल रूप से कुंडलित खोल होता है जो कक्षों में विभाजित होता है। इसका खोल रंगीन और चमकदार होता है, जो इसे मोलस्का फाइलम से संबंधित एक सेफेलोपोड के रूप में पहचान दिलाता है।
Answer:
The organism in the given picture is Nautilus and it belongs to phylum Mollusca.
In simple words: The image shows a Nautilus, a marine mollusc characterized by its distinctive chambered spiral shell.

🎯 Exam Tip: Identify molluscs by their soft bodies, often protected by a shell (like in Nautilus), and the presence of a mantle and a muscular foot.

Question 9.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र 'एम्फियोक्सस' नामक एक सेफेलोकोर्डेट को दर्शाता है, जिसमें एक लंबा, मछली जैसा शरीर होता है जो स्पष्ट रूप से खंडित नहीं होता है। यह एक पारदर्शी जलीय जीव है जिसके शरीर में नोटोकॉर्ड और तंत्रिका रज्जु जैसी कॉर्डेट विशेषताएं दिखाई देती हैं, जो इसे फाइलम कॉर्डेटा के उप-फाइलम सेफेलोकोर्डेटा से संबंधित करती है।
Answer:
The organism in the given picture is Amphioxus and it belongs to Phylum Chordata (Subphylum Cephalochordata).
In simple words: The depicted organism is Amphioxus, a Cephalochordate, belonging to Phylum Chordata, known for retaining its notochord throughout life.

🎯 Exam Tip: Remember that Cephalochordates (like Amphioxus) are primitive chordates that retain chordate characteristics, including the notochord, throughout their adult lives.

6. Observe And Identify Body Symmetry Of Given Animals.

Question 1.
Observe and identify body symmetry of given animals.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र तीन अलग-अलग जानवरों को दर्शाता है: पहला एक असमान संरचना वाला समुद्री स्पंज है, दूसरा रेडियल समरूपता वाली एक जेलीफिश है, और तीसरा द्विपक्षीय समरूपता वाला एक कीट (सिकाडा) है। ये चित्र विभिन्न प्रकार की शारीरिक समरूपताओं को स्पष्ट रूप से प्रस्तुत करते हैं।
Answer:
Fig i. represents asymmetry
Fig ii. represents radial symmetry
Fig iii. represents bilateral symmetry
In simple words: The images illustrate three types of body symmetry: Fig i shows an asymmetrical organism, Fig ii shows radial symmetry (like a jellyfish), and Fig iii shows bilateral symmetry (like an insect).

🎯 Exam Tip: Understand the three main types of body symmetry (asymmetry, radial, bilateral) as fundamental criteria for classifying animals and their evolutionary relationships.

Practical/Project:

Question 1.
Study different animals in kingdom Animalia and prepare the chart with detail scientific information.
Answer:
Phylum Porifera (Pori - Pores: feron - bearing): Members of the phylum Porifera are also called sponges. Characteristic features of the phylum:
1. Habitat: They are aquatic, mostly marine but few species are found in fresh water.
2. Forms: They are sedentary animals (attached to substratum or rock).
3. Body shape: They have asymmetrical body. Body of these animals consists of many cells with minimal
division of labour among cells. Hence, their body is considered as a colony of different types of cells.
4. Body surface: Their body bears minute pores called 'ostia' through which water enters the spongocoel (body cavity). Water leaves the body through a large opening called 'osculum'. Beating of flagella creates water current.
5. Circulation: Water is circulated in the body through the 'canal system'. When the water enters the body of poriferans, cells absorb the food, exchange respiratory gases and release excretory products.
6. Digestive system: The body cavity of sponges (spongocoel) is lined by unique type of flagellated cells called choanocytes or collar cells for digestion.
7. Endoskeleton: The body of sponges consists of calcareous / siliceous spicules and proteinaceous 'spongin fibres'.
8. Reproduction: Sponges reproduce asexually as well as sexually. Asexual reproduction takes place by fragmentation and gemmule formation. Sexual reproduction is by formation of gametes. Fertilization is internal and development is indirect through larval stage.
9. Sponges have great power of regeneration.
e.g. Scypha, Euspongia (Bath sponge), Euplectella (Venus' flower basket).

Characteristics Of Members Belonging To Phylum Cnidaria:

1. Habitat: They are aquatic, mostly marine and few of them are fresh - water forms.
2. Forms: They are sessile or free swimming.
3. Cnidoblasts: Presence of cnidoblasts or stinging cells are present on the tentacles for anchorage, offence and defence.
4. Body Symmetry: They have radially symmetrical body.
5. Germ layer: They are diploblastic.
6. Body cavity: Cnidarians have a central cavity called coelenteron or gastrovascular cavity, which helps in digestion and circulation. They have blind-sac body plan i.e., single pore opening to the exterior in the digestive system.
7. Body form: Members of this phylum exhibit two body forms. The cylindrical form, known as polyp e.g. Hydra and the umbrella - like form (.Aurelia - jelly fish) is known as medusa.
8. Digestion: They have extracellular and intracellular digestion.
9. Reproduction: Cnidarians reproduce asexually and sexually.
Asexual reproduction takes place by budding and regeneration. Sexual reproduction takes place gamete formation. They exhibit metagenesis i.e. alternation of polypoid generation with medusoid generation. Polyps produce medusae asexually and medusae produce polyps sexually, e.g. Obelia
e.g. Hydra, Aurelia (Jellyfish), Physalia (Portuguese man-of-war), Adamsia (Sea anemone), Diploria (Brain coral), Gorgonia (sea fan).
The members of this phylum are commonly known as comb jellies and sea walnuts. They are also known as acnidarians as they lack cnidoblasts. The phylum is considered as one of the minor phyla as it is represented by very few members.

Salient Features Of Phylum Ctenophora:

1. Habitat: They are exclusively marine.
2. Forms: They are free swimming animals.
3. Germ layers: Members of this phylum are diploblastic.
4. Body Symmetry: They are radially symmetrical.
5. Body plan: The animals of this phylum show blind-sac body plan.
6. Body organization: They show tissue level organization.
7. Locomotion: It is earned out by eight rows of ciliated comb plates.
8. Bioluminescence: It is the characteristic feature of the members of this phylum.
9. Digestion: It is extracellular and intracellular.
10. Reproduction: Reproduction is sexual with indirect development.
11. Colloblasts: These sticky cells are used to capture prey, e.g. Pleurobrachia, Ctenoplana
In simple words: This project involves creating a detailed chart for various animal phyla like Porifera, Cnidaria, and Ctenophora, outlining their habitat, body forms, symmetry, distinctive features, and reproductive strategies to provide comprehensive scientific information.

🎯 Exam Tip: For practicals, organize information systematically using headings, bullet points, and clear examples. Pay attention to unique features that distinguish each phylum from others.

11th Biology Digest Chapter 4 Kingdom Animalia Intext Questions And Answers

Can You Recall? (Textbook Page No. 29)

 

Question (i). What is the basis for classification?
Answer: Grades of organization, body symmetry, body cavity, germ layers and segmentation form the basis for classification.
In simple words: Animal classification is primarily based on structural features like how organized their body is, their overall shape, internal body spaces, the number of embryonic cell layers they have, and if their bodies show repeating segments.

🎯 Exam Tip: Remember these five key criteria - grades of organization, body symmetry, body cavity, germ layers, and segmentation - as they are foundational for understanding animal diversity and taxonomy.

 

Question (ii). Who proposed Five kingdom classification system?
Answer: Robert Whittaker proposed the five kingdom system of classification.
In simple words: The five-kingdom classification system, which categorizes life into Monera, Protista, Fungi, Plantae, and Animalia, was introduced by Robert Whittaker.

🎯 Exam Tip: Knowing the scientist associated with major biological classification systems, like Whittaker for the five-kingdom model, is important for general knowledge and direct recall questions.

 

Question (iii). What is the need and importance of classification?
Answer: Need and importance for classification:
a. Classification facilitates the identification of animals with great accuracy.
b. The study of animals becomes convenient.
c. It helps in understanding the relationship of animals with other living organisms.
d. It helps to understand the habitat of each animal along with its role in nature.
e. By studying few animals from a group, we can gain a better understanding about the entire group.
f. It helps in understanding different adaptations shown by animals.
g. It gives an idea about evolution of animals.
In simple words: Classification is essential because it allows us to accurately identify animals, simplifies their study, reveals evolutionary relationships, and helps us understand their habitats and adaptations by generalizing characteristics within groups.

🎯 Exam Tip: Listing the various benefits of classification, from ease of study to understanding evolution, demonstrates a comprehensive grasp of its significance in biology.

Observe And Discuss. (Textbook Page No. 29)

 

Question. Discuss the criteria of classification.
Answer: 1. The given diagrams represents the number of germ layers and body symmetry used as criteria for animal classification.
2. Number of germ layers:
(a) When an organism shows only two germ layers, they are called diploblastic animals. In this case, the outer ectoderm is separated from the inner endoderm by a non-living substance called mesoglea.
(b) When an organism shows three germinal layers, they are called triploblastic animals. The three layers are namely - outer ectoderm, middle mesoderm and inner endoderm.
3. Body symmetry:
Body symmetry implies to the similarity in shape, size and number of parts on the opposite sides of a median line when body is divided into two halves by an imaginary line along different plane. Animals may be asymmetrical, radially symmetrical or bilaterally symmetrical.
(a) Asymmetrical animals:
An animal is said to be asymmetrical when its body cannot be divided into two identical halves in any plane.
(b) Radially symmetrical animals:
In certain animals, body can be cut or divided into two similar halves in a number of planes wherein, all the cuts (planes) pass through the centre. This type of symmetry is called radial symmetry.
(c) Bilaterally symmetrical animals:
In this type, the body of the animal can be bisected or divided in two equal or identical halves by a single median or vertical plane.
In simple words: Animal classification criteria include the number of embryonic germ layers (two for diploblastic, three for triploblastic) and body symmetry (asymmetrical, radial, or bilateral), determining how the body can be divided into similar halves.

🎯 Exam Tip: Clearly defining and giving examples of diploblastic/triploblastic organisms and each type of body symmetry will earn full marks. Diagrams, if allowed, can further enhance your answer.

Internet My Friend. (Textbook Page No. 30)

 

Question. Which are the larval stages of Porifera.
Answer: Larval stages of Porifera:
Parenchymula - Flagellate larvae of calcinean sponges
Amphiblastula - Free swimming larval stage of Sycon and many other calcareous sponges. Rhagon- Larval stage which give rise to the leuconoid condition in demospongiae.
[Students are expected to find more information about the larval stages of Porifera on internet.]
In simple words: Porifera, or sponges, have several larval stages, including the flagellated parenchymula and the free-swimming amphiblastula, which are crucial for their dispersal and development into adult forms.

🎯 Exam Tip: Be precise with the names of the larval stages (Parenchymula, Amphiblastula, Rhagon) and associate them with their respective sponge types or developmental pathways.

Find Out. (Textbook Page No. 31)

 

Question. Information about coral reefs and sea fan.
Answer: Coral reefs:
1. A coral reef is an underwater ecosystem characterized by reef building corals.
2. Coral reefs constitute 25% of all marine species on the planet.
3. They belong to phylum Cnidaria.
4. There are three main types of coral reefs - fringing, barrier and atoll. Coral reefs provide ecosystem services for tourism, fisheries and shoreline protection.
5. They cannot survive in high temperatures, thus due to climate change there is a sharp decline in their population.
Sea fan or Gorgonia:
1. It is a soft coral composed of numerous polyps - cylindrical, sessile (attached) forms that grow together in a flat, fan-like pattern.
2. It belongs to phylum Cnidaria.
3. It does not produce calcium carbonate skeletons.
[Students can find out more information about coral reefs and sea fan using internet ]
In simple words: Coral reefs are vital underwater ecosystems formed by Cnidarian corals, supporting vast marine biodiversity and providing various ecological services, while sea fans (Gorgonia) are also Cnidarians known for their soft, fan-like growth patterns without rigid calcium carbonate skeletons.

🎯 Exam Tip: For coral reefs, highlight their biological classification (Cnidaria), ecological importance, types, and vulnerability to climate change. For sea fans, emphasize their soft coral nature and growth form.

Can You Tell? (Textbook Page No. 32)

 

Question (i). State the parasitic adaptations in Liver fluke and Ascaris.
Answer: Parasitic adaptations in Liver fluke:
a. Presence of hooks and suckers
b. Body covered with cuticle
c. Lacks digestive system
d. They are hermaphrodites
Parasitic adaptations in Ascaris:
a. Presence of muscular pharynx for sucking the food.
b. Body covered by tough, thick and resistant cuticle.
c. Secretes enzymes against the enzymes secreted by the host.
d. Respiration is anaerobic.
e. Reproductive system is highly developed.
In simple words: Liver flukes are adapted with hooks and suckers for attachment, a protective cuticle, and hermaphroditism, lacking a complete digestive system; Ascaris has a muscular pharynx, a tough cuticle, secretes counter-enzymes, uses anaerobic respiration, and has a highly developed reproductive system for parasitic survival.

🎯 Exam Tip: When describing parasitic adaptations, focus on features that aid attachment, protection from host defenses, efficient nutrient uptake, and high reproductive capacity, as seen in liver flukes and Ascaris.

 

Question (ii). Give example of free living platyhelminth.
Answer: Planaria
In simple words: Planaria is a common example of a free-living platyhelminth, known for its remarkable regenerative abilities.

🎯 Exam Tip: Planaria is the classic example for free-living flatworms, distinguishing it from parasitic forms like tapeworms or flukes.

Find Out. (Textbook Page No. 33)

 

Question. What are the merits and demerits of hermaphroditism?
Answer: Hermaphroditism is the condition in which an organism possesses reproductive organs of both the sexes.
Merits of hermaphroditism:
a. Assured fertilization which reduces the risk of a species to become extinct due t unavailability of mating partner.
b. Energy required for searching out mating partner is conserved.
c. Frequency of mating is maximized.
Demerits of hermaphroditism:
a. More energy is required to maintain both the reproductive systems.
b. Limited gene diversity.
[Source: http://floydbiology. blogspot. com/2012/06/httpmattc-thinks. html]
[Students are expected to find more information using the internet.]
In simple words: Hermaphroditism offers advantages like guaranteed fertilization and energy saving by eliminating the need to find a mate, but it comes with the drawbacks of higher energy investment to maintain two reproductive systems and potentially limited genetic diversity.

🎯 Exam Tip: To effectively answer this, define hermaphroditism first, then clearly list at least two merits (e.g., assured reproduction, energy saving) and two demerits (e.g., high energy cost, limited genetic variation).

 

Question. Why are leeches used in Ayurveda?
Answer: a. Leeches are used in blood purification therapy to treat many diseases as they suck impure blood from the affected site of the patient's body.
b. The anticoagulant - hirudin present in saliva of leech, inhibits the coagulation of blood and makes blood thinner. This dissolves the clots found in vessels and facilitates the blood supply.
In simple words: Leeches are used in Ayurveda for blood purification, as they remove impure blood and their saliva contains hirudin, an anticoagulant that thins blood and dissolves clots, improving blood circulation.

🎯 Exam Tip: The key points here are "blood purification" and the role of "hirudin" in preventing coagulation and facilitating blood flow; mention these explicitly for a complete answer.

 

Question. What is the role of earthworms in agriculture? What is vermicompost?
Answer: Role of earthworms in agriculture:
a. Earthworms loosen the soil by burrowing deep into it, thus they help to aerate the soil.
b. This continuous digging of soil also helps the water to reach the roots quickly.
c. Earthworms can decompose the organic matter from the soil and convert it into rich manure.
d. This helps in increasing the fertility of soil which ultimately increases the crop production.
e. Earthworm castings are rich in nutrients which act as natural fertilizer.
Vermicompost:
Vermicompost is the product of vermicomposting. It is organic manure produced as vermicast by earthworm feeding on biological waste material and plant residues.
In simple words: Earthworms significantly improve soil quality in agriculture by aerating it through burrowing, enhancing water penetration, and converting organic waste into nutrient-rich vermicompost, which is their excretory product.

🎯 Exam Tip: Focus on the earthworm's mechanical actions (burrowing, aeration, water penetration) and chemical contribution (decomposition, nutrient-rich castings/vermicompost) to agricultural fertility.

Can You Tell? (Textbook Page No. 34)

 

Question (i). Explain the term metameric segmentation.
Answer: In some animals, body consists of many segments arranged along the length of the body. When the external segmentation coincides with the internal segmentation, it is called as metameric segmentation and the phenomenon is called metamerism.
In simple words: Metameric segmentation refers to a body plan where an animal's body is composed of repeating segments, both externally and internally, along its length, a phenomenon known as metamerism.

🎯 Exam Tip: Emphasize that metameric segmentation involves both external and internal repetition of segments, distinguishing it from superficial segmentation.

 

Question (ii). Give characteristics of Arthropoda.
Answer: Arthropoda (Arthros: Joint, Podos: leg): Arthropoda forms the largest phylum of kingdom Animalia. Characteristics of Arthropoda:
a. Habitat: Arthropods are omnipresent.
b. Forms: Solitary or colonial, most of them are free-living. Barnacles are sedentary. Few are parasitic and sanguivorous, (e.g. Female mosquito, bed bug.)
c. Body symmetry: Body is bilaterally symmetrical.
d. Germ layers: They are triploblastic.
e. Body cavity: Arthropods are eucoelomates.
f. Body plan: They show tube within tube body plan.
g. Level of body organization: They show organ system level of organization.
h. Special features: The members of this phylum have jointed appendages. Hence, they are known as arthropods. Some insects like honey bee, ants, termites, etc. exhibit polymorphism.
i. Exoskeleton: Body is covered by a tough, non - living chitinous exoskeleton. As the exoskeleton does not allow body growth, arthropods shed off their exoskeleton periodically during growth. This process is called moulting or ecdysis.
j. Body division: Body is divided into head, thorax and abdomen.
k. Segmentation: Body shows metameric segmentation.
I. Digestion: Digestive system is complete and divided into foregut, midgut and hindgut.
m. Circulation: Circulatory system is of open type wherein, blood flows through body cavity called haemocoel.
n. Respiration: Respiration occurs through respiratory organs like gills, trachea, book lungs or book gills.
o. Excretion: Excretion takes place by green glands, Malpighian tubules or coxal glands.
p. Nervous system: Nervous system consists of nerve ring and double, ventral ganglionated nerve cord.
q. Sense organs:Arthropods have well developed sense organs in the form of antennae, simple or compound eye and various receptors.
r. Sexual reproduction: Sexes are generally separate in arthropods with distinct sexual dimorphism.
s. Significance:
Beneficial arthropods: Some arthropods are of economic importance. For example, Honey bees (Apis) are important for their honey and wax, silk worms for the production of silk. Lobsters, prawns, crabs are edible. Harmful arthropods: Some arthropods are harmful and act as vectors to spread various diseases, e.g., Mosquitoes. Locusta (locust) is a gregarious pest. Limulus (King crab) is a living fossil.
Other examples: Cockroach (Periplaneta), butterfly, scorpion (Hottentotta) and millipede (Archispirostreptus) prawn.
In simple words: Arthropods are the largest animal phylum, characterized by jointed appendages, a tough chitinous exoskeleton that requires moulting, bilateral symmetry, triploblastic development, a true coelom, and an open circulatory system, with a body typically divided into head, thorax, and abdomen.

🎯 Exam Tip: Highlight the defining features of Arthropoda: jointed appendages, chitinous exoskeleton, and segmentation. Also mention their bilateral symmetry, triploblastic nature, and organ system level of organization for a comprehensive answer.

 

Question (iii). Enlist the harmful Arthropods.
Answer: Significance:
Beneficial arthropods: Some arthropods are of economic importance. For example, Honey bees (Apis) are important for their honey and wax, silkworms for the production of silk. Lobsters, prawns, crabs are edible. Harmful arthropods: Some arthropods are harmful and act as vectors to spread various diseases, e.g., Mosquitoes. Locusta (locust) is a gregarious pest. Limulus (King crab) is a living fossil.
In simple words: Harmful arthropods include mosquitoes, which spread diseases, and locusts (Locusta), which are gregarious pests known for devastating crops.

🎯 Exam Tip: Focus on examples like mosquitoes (disease vectors) and locusts (agricultural pests) when asked to enlist harmful arthropods.

Find Out. (Textbook Page No. 34)

 

Question (i). Why is phylum Arthropoda considered as most successful phylum?
Answer: Phylum Arthropoda is considered as most successful phylum because of the following reasons:
a. Phylum Arthropoda is the largest phylum of kingdom Animalia. It includes various forms like lobsters, prawns, crabs, insects, millipedes, locust, honeybees, etc.
b. They are omnipresent (present everywhere). Arthropods show great variety of adaptations as their habitat varies from terrestrial to aquatic habitat.
c. Several others factors also contribute to the success of the phylum which includes:
1. The exoskeleton of arthropods is made up of tough chitinous exoskeleton. This enables them to survive on lands in almost all environment and is a great defense against predators.
2. They possess jointed appendages which allow complex movements.
3. They exhibit moulting or eedysis.
4. They have metamerically segmented body helping in movement around diverse environments.
In simple words: Arthropods are highly successful due to their immense diversity as the largest phylum, omnipresence across varied habitats, protective chitinous exoskeleton, flexible jointed appendages, and metamerically segmented bodies, all contributing to their adaptability and survival.

🎯 Exam Tip: Emphasize their species diversity, wide distribution, adaptable exoskeleton, jointed appendages, and segmented body as key factors contributing to their evolutionary success.

 

Question (ii). What do we mean by parthenogenesis?
Answer: Development of an egg into a complete individual without fertilization is known parthenogenesis. It is found in many non-vertebrates such as bees, rotifers and even some lizards and birds (turkey).
In simple words: Parthenogenesis is a form of asexual reproduction where an egg develops into a complete organism without being fertilized by a sperm.

🎯 Exam Tip: A clear definition stating "development of an egg into a complete individual without fertilization" is sufficient. Mentioning common examples like bees or rotifers adds value.

 

Question (iii). What do we mean by living fossil?
Answer: A member of a living animal or plant species that is almost identical to species known from the fossil record (not the recent fossil record), i.e. they have changed very little over a long period.
[Source:https://www. encyclopedia, com/earth-and-environment/ecology-and-environmentalism/environmental-studies/living-fossil]
In simple words: A living fossil is an organism that has remained largely unchanged morphologically for millions of years, closely resembling its ancient ancestors found in the fossil record.

🎯 Exam Tip: The core concept of a "living fossil" is minimal evolutionary change over vast geological timescales, making it appear similar to its ancient fossilized relatives.

 

Question (iv). How the bees produce honey?
Answer: a. Bees produce honey using the nectar of flowering plants. A bee sucks the nectar and stores it in a honey sac until it returns to the hive.
b. The nectar is then transferred to worker bees in the hive who suck the nectar from the honey sac through their proboscis. This nectar contains 70% water and 20% honey. Honeybees get rid of excess water by swallowing and regurgitating the nectar again and again. They also fan their wings over filled cells of honeycomb.
When most of the water has evaporated from the honeycomb, the bee seals the comb with a secretion of liquid from its abdomen which eventually hardens into beeswax. This is how the honey bees use nectar to produce a thick, sticky and sweet honey.
In simple words: Bees collect nectar, store it in a honey sac, and then process it in the hive by repeatedly regurgitating and fanning it to evaporate water, eventually concentrating it into honey before sealing it with beeswax.

🎯 Exam Tip: Describe the process sequentially: nectar collection, transfer, water evaporation (through regurgitation and fanning), and final storage/sealing as honey.

 

Question (v). What will happen if arthropods do not moult?
Answer: a. Moulting or eedysis is a periodic shedding of the outer cuticle layer of body in arthropods.
b. The outer layer of body of arthropods is formed of tough, non-living chitinous substance.
c. If arthropods do not moult, they cannot grow and mature into adult forms
In simple words: If arthropods could not moult, their rigid chitinous exoskeleton would prevent them from growing, meaning they would remain small and unable to develop into mature adult forms.

🎯 Exam Tip: Connect the non-living nature of the chitinous exoskeleton to the necessity of moulting for growth. Without moulting, growth and maturation are impossible.

Can You Tell? (Textbook Page No. 34)

 

Question. Why do Molluscs have shell?
Answer: Molluscs are soft-bodied animals. Thus, the calcareous shell provides supports and protects the organisms from predators.
In simple words: Molluscs possess a calcareous shell primarily for physical protection against predators and to provide structural support for their soft bodies.

🎯 Exam Tip: The two main functions of the mollusc shell are protection and support; highlight both for a complete answer.

Can You Tell? (Textbook Page No. 36)

 

Question. Give salient features of phylum Echinodermata.
Answer: Salient features of phylum Echinodermata (Echinus - spines, derma - skin)
1. Habitat: These are exclusively marine.
2. Forms: Members of this phylum are solitary, sedentary or free-living and gregarious, benthic.
3. Body symmetry: These animals are radially symmetrical with pentamerous symmetry.
4. Shape: Members of Echinodermata are spherical, elongated or star-shaped.
5. Body: The endoskeleton is made up of calcareous ossicles. Spines are formed on the body. Hence, they are known as echinoderms. The body has two sides oral and aboral and lacks definite divisions. Mouth is ventrally present on oral surface and anus on aboral surface.
6. Water vascular system: Presence of water vascular system is the peculiar character of echinoderms. The madreporite is the opening of water vascular system through which water enters. Water vascular system is useful in locomotion, food capturing, respiration.
7. Digestion: Digestive system is complete.
8. Respiration: Peristomial gills, papillae, respiratory tree, etc. are used for respiration.
9. Circulatory and excretory systems: Absent in echinoderms.
10. Nervous system: Nervous system is simple with a nerve ring around the mouth and radial nerves in arms.
11. Reproduction and development: Sexes are separate (sometimes bisexual). Fertilization is external.
12. Development is indirect, i.e. through larval stages. They show high power of regeneration.
e.g. Sea lily (Antedon), Sea star (Asterias), Sea cucumber (Cucumaria), Brittle star (Ophiothrix), Sea urchin (Echinus).
In simple words: Echinoderms are exclusively marine animals characterized by a radially symmetrical body (often pentamerous in adults), a calcareous endoskeleton with spines, and a unique water vascular system crucial for locomotion, feeding, and respiration.

🎯 Exam Tip: Key features to highlight for Echinodermata are their marine habitat, radial/pentamerous symmetry, calcareous endoskeleton, and the distinctive water vascular system with its multiple functions.

 

Question. Can you tell? (Textbook Page No. 36)
Answer: 1. Hemiehordata was earlier considered as sub phylum of Chordata because the buccal diverticulum was considered as notochord. It is now placed as a separate phylum under Non-Chordata.
2. It possesses certain characteristics of both Chordates and Non-chordates.
In simple words: Hemichordata was previously grouped under Chordata due to their buccal diverticulum being mistaken for a notochord, but it's now a distinct non-chordate phylum, exhibiting traits from both groups.

🎯 Exam Tip: Note the reclassification of Hemichordata from a Chordate subphylum to a separate Non-Chordate phylum, and remember that their "notochord" (buccal diverticulum) is a key point of confusion.

Find Out. (Textbook Page No. 36)

 

Question. Why Balanoglossus is considered as connecting link between Non-chordates and chordates?
Answer: Balanoglossus belongs to phylum Hemiehordata. For Explanation:
1. Hemiehordata was earlier considered as sub phylum of Chordata because the buccal diverticulum was considered as notochord. It is now placed as a separate phylum under Non-Chordata.
2. It possesses certain characteristics of both Chordates and Non-chordates.
3. Absence of notochord worm-like body, heart located on the dorsal side are the Non-chordate like characteristics seen in Hemiehordata.
4. Presence of nerve chord, pharyngeal gill slits are some of the Chordate-like characters seen in Hemiehordata. Hence, Hemiehordata is considered as a connecting link between Non-chordata and Chordata.
In simple words: Balanoglossus is seen as a connecting link between non-chordates and chordates because it shows both non-chordate features like its worm-like body and dorsal heart, along with chordate features such as a nerve cord and pharyngeal gill slits.

🎯 Exam Tip: To explain why Balanoglossus is a connecting link, identify at least two chordate characteristics (e.g., nerve cord, gill slits) and two non-chordate characteristics (e.g., dorsal heart, worm-like body) it possesses.

Observe And Discuss. (Textbook Page No. 36)

 

Question. Compare and contrast between Non-Chordates and Chordates.
ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र नॉन-कॉर्डेट्स और कॉर्डेट्स के बीच तुलना को दर्शाता है। नॉन-कॉर्डेट के आरेख में एक एक्सोस्केलेटन, एक धड़कने वाली पृष्ठीय रक्त वाहिका, एक पृष्ठीय तंत्रिका रज्जु, एक पाचन नली और एक गुदा दिखाई गई है। कॉर्डेट के आरेख में एक नोटोकॉर्ड, पृष्ठीय तंत्रिका रज्जु, पाचन नली, गुदा, गलफड़ा छिद्र, पश्च-गुदा पूंछ और एक अधर हृदय दिखाया गया है।
Answer:

Non-chordates	enoraates
1. Notochord is absent.	Notochord present at least in the early embryonic life.
2. Nerve cord is ventral, paired and ganglionated.	Nerve cord is single, dorsal and non-ganglionated.
3. The heart, if present is dorsal.	The heart is ventral in position.
4. Pharyngeal gill slits are absent.	Pharyngeal gill slits are present at least in embryonic stage.
5. Post-anal tail is absent.	Post-anal tail is present at least in embryonic stage.

In simple words: Non-chordates typically lack a notochord, have a ventral and ganglionated nerve cord, and a dorsal heart (if present), while chordates possess a notochord at some life stage, a single dorsal nerve cord, and a ventral heart, along with pharyngeal gill slits and a post-anal tail.

🎯 Exam Tip: When comparing chordates and non-chordates, highlight the presence/absence and position of the notochord, nerve cord, heart, pharyngeal gill slits, and post-anal tail, as these are the defining characteristics.

Can You Tell? (Textbook Page No. 37)

 

Question. Herdmania is called a Chordate. Explain.
Answer: 1. Herdmania belongs to phylum Urochordata.
2. It is called a chordate as it shows the following features:
a. Presence of notochord at least in early embryonic life. (In Herdmania, notochord is present in the tail of the larval forms).
b. Presence of hollow, dorsal nerve chord, running throughout the length of the body.
c. Presence of pharyngeal gill slits.
d. Presence of post-anal tail.
In simple words: Herdmania is classified as a chordate because its larval stage exhibits the four key chordate features: a notochord in the tail, a hollow dorsal nerve cord, pharyngeal gill slits, and a post-anal tail, even though these may be reduced or absent in adulthood.

🎯 Exam Tip: Crucially, emphasize that Herdmania exhibits chordate characteristics (notochord, nerve cord, gill slits, post-anal tail) during its larval stage, even if they are lost in the adult form.

 

Question. Give characteristics of Petromyzon. Comment on its mode of nutrition.
Answer: Characteristic features of class Cyclostomata (Cyclos: Circular, stoma-mouth) Lat/Grk
1. Members of class Cyclostomata are jawless and eel-like organisms.
2. Their skin is devoid of scales, soft and smooth, containing unicellular mucus glands.
3. Median fms are present but paired fins are absent.
4. They are ectoparasites on fishes.
5. They have sucking circular mouth, without jaws.
6. Cranium and vertebral column are made up of cartilage.
7. Their digestive system lacks stomach.
8. Respiration occurs by 6 - 15 pairs of gill slits. Gills slits are without operculum.
9. Heart is two chambered with one auricle and one ventricle.
10. Gonad is single, large and without gonoduct.
11. Fertilization is external. They are anadromous as they migrate for spawning to fresh - water from marine habitat.
12. After spawning, they die within few days. Larvae metamorphosize and migrate to ocean.
e.g Petromyzon (Lamprey), Myxine (Hagfish).
In simple words: Petromyzon (lamprey) is a jawless, eel-like cyclostome with a cartilaginous skeleton, lacking scales and paired fins, and breathes through 6-15 gill slits; its mode of nutrition is ectoparasitic, feeding on other fishes with its sucking mouth.

🎯 Exam Tip: For Petromyzon, focus on its jawless, ectoparasitic nature, circular sucking mouth, and cartilaginous skeleton, along with the absence of scales and paired fins, as defining characteristics.

Can You Tell? (Textbook Page No. 38)

 

Question (i). What is the lateral line system?
Answer: a. Lateral line system is the system with mechanoreceptors called neuromasts, for the detection of watei current.
b. These neuromasts are arranged in an interconnected network along the head and body.
c. Lateral line system also known as lateralis system.
In simple words: The lateral line system is a sensory system in aquatic animals, primarily fish, composed of mechanoreceptors called neuromasts that detect water currents and vibrations, helping them navigate and locate prey.

🎯 Exam Tip: Define the lateral line system as a mechanoreceptive sensory system (using neuromasts) for detecting water currents and vibrations in aquatic animals.

 

Question (ii). Why Piscian heart is called a venous heart?
Answer: a. Pisces have two-chambered heart. They have single and closed circulation.
b. Heart of Pisces receives blood only from veins and thus always shows presence of deoxygenated blood which it pumps directly to the gills for oxygenation. Thus, the heart of Pisces is called a venous heart.
In simple words: A Piscian heart is called a venous heart because it only receives deoxygenated blood from the body, which it then pumps directly to the gills for oxygenation before it circulates to the rest of the body.

🎯 Exam Tip: The key reason is that the fish heart exclusively pumps deoxygenated (venous) blood to the gills, never oxygenated blood directly to the body, making it a "venous" heart.

Can You Tell? (Textbook Page No. 40)

 

Question. Amphibians do not have exoskeleton. Give reason.
Answer: 1. Amphibians live in both water and on land.
2. They perform cutaneous respiration (i. e. gaseous exchange across the skin or outer integument.) under water and when on land, they respire through lungs. Thus, to facilitate cutaneous respiration, amphibians do not have exoskeleton.
In simple words: Amphibians lack an exoskeleton because their skin is crucial for cutaneous respiration both in water and on land, and a hard outer covering would impede this vital gas exchange.

🎯 Exam Tip: The primary reason is that a soft, moist skin is essential for cutaneous respiration, which would be hindered by an exoskeleton.

 

Question. Why are amphibians and reptilians called poikilotherms?
Answer: Amphibians and reptilians are called poikilotherms as they cannot maintain a constant body temperature. Their body temperature changes according to the change in surrounding temperature.
In simple words: Amphibians and reptiles are called poikilotherms because their body temperature fluctuates directly with the surrounding environmental temperature, as they cannot internally regulate it to remain constant.

🎯 Exam Tip: The definition of poikilothermy is directly tied to the inability to maintain a constant internal body temperature, leading to fluctuations with the external environment.

Can You Tell? (Textbook Page No. 41)

 

Question. Give adaptations in Aves for flying.
Answer: 1. In birds, the forelimbs are modified into wings for flying.
2. They possess stream-lined body to reduce resistance during flight.
3. Bones are hollow or pneumatic to reduce body weight.
4. In order to reduce body weight, urinary bladder is absent. Also, females possess only left ovary and oviduct.
5. Body is covered by feathers to facilitate flying.
In simple words: Birds are adapted for flight with forelimbs modified into wings, a streamlined body, hollow bones for reduced weight, absence of a urinary bladder, and only one functional ovary/oviduct in females, all covered by feathers to aid aerodynamics.

🎯 Exam Tip: When listing flight adaptations, include both structural (wings, streamlined body, feathers, hollow bones) and physiological (absence of bladder, reduced reproductive organs) features that minimize weight and enhance aerodynamics.

 

Question (i). Aves and mammals are homeotherms. Give reason.
Answer: a. Aves and mammals can generate heat to maintain their body temperature.
b. They keep their body temperature constant, irrespective of fluctuations in environmental temperature. Thus, Aves and mammals are homeotherms.
In simple words: Aves and mammals are homeotherms because they can internally generate and regulate their body heat, allowing them to maintain a stable, constant body temperature regardless of external environmental changes.

🎯 Exam Tip: The core concept of homeothermy is the ability to maintain a constant internal body temperature through metabolic heat generation, independent of external temperature fluctuations.

 

Question (ii). How mammals differ from other groups of animals?
Answer: Features of class Mammalia (mammae: breasts, nipple):
1. Special feature: Presence of mammary glands (milk-producing glands) for the nourishment of young ones. Mammary glands are modified sweat glands.
2. Habitat: Mammals are omnipresent (present everywhere). These are mostly terrestrial, some are aquatic and few are aerial and arboreal (living on trees).
3. Locomotion: Limbs are the organs of locomotion and are modified for walking, climbing, burrowing, swimming, etc.
4. Body division: Body is differentiated into head, neck, trunk and tail. They have external ear (pinna).
5. Body temperature: Mammals are homeotherms or warm-blooded animals.
6. Exoskeleton: It is in the form of hair, fur, nails, hooves, horns, etc.
7. Skin: Skin is glandular and has sweat glands and sebaceous (oil) glands.
8. Mouth cavity: Mammals show heterodont dentition (various types of teeth like incisors, canines, premolars and molars).
9. Circulation: Heart is ventral in position, four chambered with two auricles and two ventricles. RBCs are biconcave and enucleated (except camel). Blood is red in colour.
10. Respiration: Respiration takes place by lungs.
11. Nervous system: Brain is highly developed. Cerebrum shows a transverse band called corpus callosum.
12. Reproduction and development: Only few mammals are oviparous, e.g. Duck billed platypus. Some have pouches for development of immature young ones. These are called marsupials, e.g. Kangaroo. Most of the mammals are placental and viviparous.
In simple words: Mammals differ from other animal groups primarily by the presence of mammary glands for feeding young, hair or fur for insulation, external ears (pinna), and heterodont dentition, along with being homeothermic and having a highly developed brain and a four-chambered heart.

🎯 Exam Tip: The most distinctive features of mammals are mammary glands, hair/fur, and external ears (pinna). Also mention their homeothermy, heterodont dentition, and advanced brain development.

Do Yourself. (Textbook Page No. 41)

 

Question. Observe different animals in your surrounding, write detailed classification and write down the characteristics of animals in following format.
Answer: (As this is a practical/project question, the detailed classification and characteristics would vary based on observation. This answer serves as an example or instruction)
In simple words: This question asks students to conduct an observational study of local animals, categorizing them systematically and noting their unique physical traits based on established biological classification formats.

🎯 Exam Tip: For this type of question, ensure you accurately identify the Phylum and Class of observed animals, and clearly list at least 3-5 distinct characteristics for each, demonstrating a good understanding of taxonomic principles.

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