FORM FOUR BIOLOGY EXAM – TOPIC: CLASSIFICATION OF LIVING THINGS (KINGDOM ANIMALIA)
Time: 3 Hours
Instructions:
- Answer all questions in Sections A and B.
- Answer two (2) questions only from Section C.
- All diagrams must be neat and properly labeled.
SECTION A (16 Marks)
1. Multiple Choice Questions (10 Marks)
Choose the most correct answer:
- Which of the following is a characteristic feature of Phylum Platyhelminthes?
- a) Segmented body
- b) Pseudocoelomate body cavity
- c) Dorsoventrally flattened body
- d) Jointed appendages
- Members of Phylum Annelida are characterized by:
- a) Radial symmetry
- b) Open circulatory system
- c) Metameric segmentation
- d) Chitinous exoskeleton
- Which class within Phylum Arthropoda includes organisms with three pairs of legs and usually two pairs of wings?
- a) Arachnida
- b) Insecta
- c) Crustacea
- d) Myriapoda
- The presence of a notochord is a defining feature of which phylum?
- a) Mollusca
- b) Chordata
- c) Echinodermata
- d) Arthropoda
- Which of the following organisms belongs to Phylum Aschelminthes?
- a) Planaria
- b) Ascaris
- c) Earthworm
- d) Leech
- Which class within Phylum Chordata is characterized by the presence of mammary glands?
- a) Reptilia
- b) Aves
- c) Mammalia
- d) Amphibia
- The excretory structures called nephridia are found in:
- a) Arthropods
- b) Annelids
- c) Platyhelminthes
- d) Chordates
- Which of the following is a characteristic of Class Arachnida?
- a) Three pairs of legs
- b) Presence of antennae
- c) Two body segments
- d) Compound eyes
- The body cavity in Aschelminthes is termed:
- a) Acoelomate
- b) Pseudocoelomate
- c) Coelomate
- d) Hemocoel
- Which class within Phylum Chordata is adapted for flight?
- a) Reptilia
- b) Amphibia
- c) Aves
- d) Mammalia
2. Matching Items (6 Marks)
Match the items in List A with the correct responses from List B:
| List A | List B |
|---|---|
| (i) Platyhelminthes | a) Presence of jointed appendages |
| (ii) Aschelminthes | b) Dorsoventrally flattened body |
| (iii) Annelida | c) Segmented body with true coelom |
| (iv) Arthropoda | d) Pseudocoelomate body cavity |
| (v) Chordata | e) Presence of notochord |
| (vi) Insecta | f) Three pairs of legs and compound eyes |
SECTION B
3. Earthworm Specimen (15 Marks)
You are provided with a preserved specimen of an earthworm.
- Identify its phylum and class. (2 marks)
- List three observable features that justify its classification. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Explain two economic importances of earthworms. (5 marks)
4. Leech Specimen (15 Marks)
During a field study, students collected a specimen of a leech.
- Classify the specimen up to its class level. (2 marks)
- List three observable features that distinguish it from earthworms. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Discuss two ways in which leeches are economically important. (5 marks)
5. Tapeworm Specimen (15 Marks)
A preserved specimen of a tapeworm is provided.
- Identify its phylum and class. (2 marks)
- List three observable features that justify its classification. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Explain two adaptations that make tapeworms effective parasites. (5 marks)
6. Grasshopper Specimen (15 Marks)
Students observed a preserved specimen of a grasshopper during a laboratory session.
- Classify the specimen up to its class level. (2 marks)
- List three observable features that justify its classification. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Discuss two economic importances of grasshoppers. (5 marks)
7. Spider Specimen (15 Marks)
A preserved specimen of a spider is provided.
- Identify its phylum and class. (2 marks)
- List three observable features that distinguish it from insects. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Explain two ways in which spiders are economically important. (5 marks)
8. Crab Specimen (15 Marks)
During a field trip, students collected a specimen of a crab.
- Classify the specimen up to its class level. (2 marks)
- List three observable features that justify its classification. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Discuss two economic importances of crabs. (5 marks)
9. Fish Specimen (15 Marks)
You are provided with a preserved specimen of a fish.
- Identify its phylum and class. (2 marks)
- List three observable features that justify its classification. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Explain two economic importances of fish. (5 marks)
10. Frog Specimen (15 Marks)
A preserved specimen of a frog is provided.
- Classify the specimen up to its class level. (2 marks)
- List three observable features that distinguish it from reptiles. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Discuss two economic importances of frogs. (5 marks)
11. Lizard Specimen (15 Marks)
During a laboratory session, students examined a preserved specimen of a lizard.
- Identify its phylum and class. (2 marks)
- List three observable features that justify its classification. (3 marks)
- Draw a labeled diagram of the specimen. (5 marks)
- Explain two economic importances of lizards. (5 marks)
SECTION C
12. Platyhelminthes vs. Aschelminthes (15 Marks)
- Compare the characteristics of Phylum Platyhelminthes and Phylum Aschelminthes. (8 marks)
- With examples, discuss the economic importance of organisms from each phylum. (7 marks)
13. Annelida Characteristics (15 Marks)
- Describe the general characteristics of Phylum Annelida. (8 marks)
- Explain the significance of segmentation in annelids. (7 marks)
14. Insecta Features (15 Marks)
- Discuss the distinguishing features of Class Insecta within Phylum Arthropoda. (8 marks)
- Explain the adaptive advantages of these features. (7 marks)
15. Chordata Characteristics (15 Marks)
- Outline the main characteristics of Phylum Chordata. (8 marks)
- Discuss how these characteristics contribute to the success of chordates in various environments. (7 marks)
FORM FOUR BIOLOGY EXAM – ANSWERS: CLASSIFICATION OF LIVING THINGS (KINGDOM ANIMALIA)
Time: 3 Hours
Instructions:
- Answers for all questions in Sections A and B are provided below.
- Answers for two questions from Section C are provided as per instructions.
- Diagrams are described due to the inability to draw directly in HTML.
SECTION A (16 Marks)
1. Multiple Choice Questions (10 Marks)
- Which of the following is a characteristic feature of Phylum Platyhelminthes?
- a) Segmented body
- b) Pseudocoelomate body cavity
- c) Dorsoventrally flattened body
- d) Jointed appendages
Explanation: Platyhelminthes, or flatworms, are characterized by a dorsoventrally flattened body, which aids in diffusion-based respiration and nutrient distribution due to their lack of a true body cavity (acoelomate).
- Members of Phylum Annelida are characterized by:
- a) Radial symmetry
- b) Open circulatory system
- c) Metameric segmentation
- d) Chitinous exoskeleton
Explanation: Annelids exhibit metameric segmentation, meaning their body is divided into repeating segments, each with similar structures, enhancing flexibility and movement.
- Which class within Phylum Arthropoda includes organisms with three pairs of legs and usually two pairs of wings?
- a) Arachnida
- b) Insecta
- c) Crustacea
- d) Myriapoda
Explanation: Insects typically have three pairs of legs and often two pairs of wings, distinguishing them from other arthropods like arachnids (four pairs of legs) or crustaceans (variable leg counts).
- The presence of a notochord is a defining feature of which phylum?
- a) Mollusca
- b) Chordata
- c) Echinodermata
- d) Arthropoda
Explanation: The notochord, a flexible rod-like structure, is a key characteristic of Chordata, present at some stage in their development, supporting the body.
- Which of the following organisms belongs to Phylum Aschelminthes?
- a) Planaria
- b) Ascaris
- c) Earthworm
- d) Leech
Explanation: Ascaris, a roundworm, belongs to Aschelminthes (also called Nematoda), characterized by a pseudocoelomate body. Planaria is a flatworm (Platyhelminthes), and earthworms and leeches are annelids.
- Which class within Phylum Chordata is characterized by the presence of mammary glands?
- a) Reptilia
- b) Aves
- c) Mammalia
- d) Amphibia
Explanation: Mammalia is defined by mammary glands, which produce milk to nourish young, a feature absent in reptiles, birds, or amphibians.
- The excretory structures called nephridia are found in:
- a) Arthropods
- b) Annelids
- c) Platyhelminthes
- d) Chordates
Explanation: Nephridia are excretory organs in annelids, facilitating waste removal in each body segment. Other groups use different excretory structures, like Malpighian tubules in arthropods.
- Which of the following is a characteristic of Class Arachnida?
- a) Three pairs of legs
- b) Presence of antennae
- c) Two body segments
- d) Compound eyes
Explanation: Arachnids, like spiders, have two body segments (cephalothorax and abdomen) and lack antennae, unlike insects, which have three body segments and antennae.
- The body cavity in Aschelminthes is termed:
- a) Acoelomate
- b) Pseudocoelomate
- c) Coelomate
- d) Hemocoel
Explanation: Aschelminthes have a pseudocoelom, a body cavity not fully lined by mesoderm, unlike the true coelom in annelids or the acoelomate condition in flatworms.
- Which class within Phylum Chordata is adapted for flight?
- a) Reptilia
- b) Amphibia
- c) Aves
- d) Mammalia
Explanation: Aves (birds) are adapted for flight with features like feathers and hollow bones, unlike amphibians, reptiles, or mammals (except bats).
2. Matching Items (6 Marks)
| List A | List B |
|---|---|
| (i) Platyhelminthes | b) Dorsoventrally flattened body |
| (ii) Aschelminthes | d) Pseudocoelomate body cavity |
| (iii) Annelida | c) Segmented body with true coelom |
| (iv) Arthropoda | a) Presence of jointed appendages |
| (v) Chordata | e) Presence of notochord |
| (vi) Insecta | f) Three pairs of legs and compound eyes |
Explanation: Each item in List A is matched with its defining characteristic. For example, Platyhelminthes are dorsoventrally flattened, Aschelminthes have a pseudocoelom, and Insecta have three pairs of legs and compound eyes.
SECTION B
3. Earthworm Specimen (15 Marks)
- Phylum and Class: Phylum Annelida, Class Oligochaeta
Explanation: Earthworms belong to Annelida due to their segmented bodies and to Oligochaeta due to their few bristles (chaetae) per segment.
- Observable Features:
- Metameric segmentation: Body divided into repeating segments.
- Clitellum: A thickened glandular band used in reproduction.
- Chaetae: Small bristles on each segment for locomotion.
Explanation: These features confirm the annelid characteristics of segmentation and a true coelom, with the clitellum specific to Oligochaeta.
- Labeled Diagram: The diagram would show a cylindrical body with visible segments, a clitellum near the anterior end, a mouth, and chaetae on the ventral surface. Labels include: mouth, clitellum, segments, anus, and chaetae.
- Economic Importance:
- Soil aeration: Earthworms burrow, improving soil structure and aeration for plant growth.
- Nutrient recycling: Their castings enrich soil with organic matter, enhancing fertility.
Explanation: Earthworms are vital for agriculture by enhancing soil quality and supporting plant growth through their activities.
4. Leech Specimen (15 Marks)
- Classification: Phylum Annelida, Class Hirudinea
Explanation: Leeches are annelids with segmented bodies, classified in Hirudinea due to their lack of chaetae and presence of suckers.
- Distinguishing Features from Earthworms:
- Absence of chaetae: Leeches lack bristles, unlike earthworms.
- Presence of suckers: Leeches have anterior and posterior suckers for attachment and movement.
- Flattened body: Leeches are dorsoventrally flattened, unlike the cylindrical earthworms.
Explanation: These features distinguish leeches within Annelida, reflecting their parasitic or predatory lifestyle.
- Labeled Diagram: The diagram would show a flattened body with anterior and posterior suckers, no visible chaetae, and a segmented appearance. Labels include: anterior sucker, posterior sucker, segments, and mouth.
- Economic Importance:
- Medical use: Leeches are used in surgery to prevent blood clotting and promote healing.
- Ecosystem role: As predators or parasites, they help control populations of other organisms.
Explanation: Leeches have medical applications due to their anticoagulant secretions and contribute to ecological balance.
5. Tapeworm Specimen (15 Marks)
- Phylum and Class: Phylum Platyhelminthes, Class Cestoda
Explanation: Tapeworms are flatworms (Platyhelminthes) and belong to Cestoda due to their ribbon-like, segmented bodies adapted for parasitism.
- Observable Features:
- Dorsoventrally flattened body: Facilitates nutrient absorption.
- Scolex with hooks/suckers: For attachment to the host’s intestine.
- Proglottids: Repeating body segments containing reproductive organs.
Explanation: These features confirm their classification as parasitic flatworms with specialized structures for host attachment and reproduction.
- Labeled Diagram: The diagram would show a flat, ribbon-like body with a scolex at the anterior end, followed by proglottids. Labels include: scolex, hooks/suckers, proglottids, and genital pores.
- Adaptations for Parasitism:
- Scolex with hooks/suckers: Ensures firm attachment to the host’s intestine.
- High reproductive capacity: Numerous proglottids produce many eggs, increasing infection success.
Explanation: These adaptations enable tapeworms to thrive as endoparasites, securing their position and maximizing reproduction within the host.
6. Grasshopper Specimen (15 Marks)
- Classification: Phylum Arthropoda, Class Insecta
Explanation: Grasshoppers are arthropods with jointed appendages and belong to Insecta due to their three body segments and three pairs of legs.
- Observable Features:
- Three body segments: Head, thorax, and abdomen.
- Three pairs of legs: Including jumping hind legs.
- Compound eyes: For wide-angle vision.
Explanation: These features align with Insecta characteristics, supporting their classification within Arthropoda.
- Labeled Diagram: The diagram would show a grasshopper with a head (compound eyes, antennae), thorax (wings, legs), and abdomen. Labels include: head, thorax, abdomen, compound eyes, antennae, wings, and jumping legs.
- Economic Importance:
- Pest in agriculture: Grasshoppers can damage crops, impacting food production.
- Food chain role: Serve as prey for birds and other animals, supporting ecosystems.
Explanation: Grasshoppers have both negative (crop damage) and positive (ecological role) economic impacts.
7. Spider Specimen (15 Marks)
- Phylum and Class: Phylum Arthropoda, Class Arachnida
Explanation: Spiders are arthropods with jointed appendages and belong to Arachnida due to their four pairs of legs and two body segments.
- Distinguishing Features from Insects:
- Four pairs of legs: Unlike insects’ three pairs.
- Two body segments: Cephalothorax and abdomen, unlike insects’ three.
- No antennae: Spiders lack antennae, unlike insects.
Explanation: These features differentiate arachnids from insects, reflecting their distinct evolutionary adaptations.
- Labeled Diagram: The diagram would show a spider with a cephalothorax, abdomen, eight legs, and spinnerets. Labels include: cephalothorax, abdomen, legs, spinnerets, and chelicerae.
- Economic Importance:
- Pest control: Spiders prey on insects, reducing agricultural pests.
- Silk production: Spider silk has potential uses in biomaterials.
Explanation: Spiders contribute to natural pest control and offer potential in biotechnological applications.
8. Crab Specimen (15 Marks)
- Classification: Phylum Arthropoda, Class Crustacea
Explanation: Crabs are arthropods with a hard exoskeleton and belong to Crustacea due to their two pairs of antennae and aquatic adaptations.
- Observable Features:
- Hard carapace: Protects the body.
- Two pairs of antennae: Unlike insects or arachnids.
- Chelipeds: Large claws for feeding and defense.
Explanation: These features confirm their classification within Crustacea, adapted for marine or freshwater environments.
- Labeled Diagram: The diagram would show a crab with a carapace, chelipeds, walking legs, and antennae. Labels include: carapace, chelipeds, antennae, walking legs, and eyes.
- Economic Importance:
- Food source: Crabs are harvested for human consumption.
- Ecosystem role: They help clean aquatic environments as scavengers.
Explanation: Crabs are economically significant in fisheries and contribute to aquatic ecosystem health.
9. Fish Specimen (15 Marks)
- Phylum and Class: Phylum Chordata, Class Actinopterygii (or Osteichthyes)
Explanation: Fish belong to Chordata due to their notochord and to Actinopterygii (ray-finned fish) due to their bony skeleton and fin structure.
- Observable Features:
- Scales: Cover the body for protection.
- Fins: For locomotion and balance.
- Gills: For respiration in water.
Explanation: These features confirm their aquatic chordate classification, adapted for swimming and respiration.
- Labeled Diagram: The diagram would show a fish with a streamlined body, fins, scales, and gills. Labels include: dorsal fin, caudal fin, pectoral fin, gills, scales, and lateral line.
- Economic Importance:
- Food source: Fish are a major protein source in diets worldwide.
- Aquaculture: Fish farming supports economies and food security.
Explanation: Fish are critical to global food systems and economic activities through fisheries and aquaculture.
10. Frog Specimen (15 Marks)
- Classification: Phylum Chordata, Class Amphibia
Explanation: Frogs are chordates with a notochord and belong to Amphibia due to their dual life in water and on land.
- Distinguishing Features from Reptiles:
- Moist skin: Frogs have permeable, moist skin, unlike reptiles’ dry scales.
- Lack of claws: Frogs have webbed feet without claws, unlike many reptiles.
- External fertilization: Frogs typically lay eggs in water, unlike reptiles’ internal fertilization.
Explanation: These features reflect amphibians’ reliance on moist environments, distinguishing them from reptiles.
- Labeled Diagram: The diagram would show a frog with moist skin, webbed feet, and bulging eyes. Labels include: eyes, tympanum, forelimbs, hindlimbs, and webbed feet.
- Economic Importance:
- Pest control: Frogs eat insects, reducing agricultural pests.
- Research: Frogs are used in scientific studies, contributing to medical advances.
Explanation: Frogs support ecosystems and science through their roles as predators and research models.
11. Lizard Specimen (15 Marks)
- Phylum and Class: Phylum Chordata, Class Reptilia
Explanation: Lizards are chordates with a notochord and belong to Reptilia due to their scaly skin and terrestrial adaptations.
- Observable Features:
- Dry, scaly skin: Protects against desiccation.
- Claws: For climbing and grasping.
- Internal fertilization: Unlike amphibians, reptiles have internal fertilization.
Explanation: These features confirm their classification as reptiles, adapted for terrestrial life.
- Labeled Diagram: The diagram would show a lizard with scaly skin, claws, and a long tail. Labels include: head, scales, claws, tail, and eyes.
- Economic Importance:
- Pest control: Lizards eat insects, reducing pest populations.
- Pet trade: Lizards are popular in the pet industry, contributing to economies.
Explanation: Lizards benefit ecosystems and economies through pest control and the pet trade.
SECTION C (Choose Two Questions)
Answering Questions 12 and 13 as examples.
12. Platyhelminthes vs. Aschelminthes (15 Marks)
- Comparison of Characteristics:
- Body Cavity: Platyhelminthes are acoelomate (no body cavity), while Aschelminthes are pseudocoelomate (body cavity not fully lined by mesoderm).
- Body Shape: Platyhelminthes are dorsoventrally flattened, aiding diffusion; Aschelminthes are cylindrical with a tough cuticle.
- Digestive System: Platyhelminthes have an incomplete digestive system (single opening); Aschelminthes have a complete digestive system (mouth and anus).
- Reproduction: Platyhelminthes are mostly hermaphroditic; Aschelminthes are often dioecious (separate sexes).
Explanation: These differences reflect distinct evolutionary adaptations, with Platyhelminthes suited for simple diffusion-based systems and Aschelminthes for more complex internal structures.
- Economic Importance with Examples:
- Platyhelminthes: Tapeworms (e.g., Taenia) cause diseases like taeniasis, impacting human and livestock health, increasing medical costs. Liver flukes (e.g., Fasciola) damage livestock, affecting agriculture.
- Aschelminthes: Parasitic nematodes (e.g., Ascaris) cause infections, leading to health issues and economic losses in treatment. Beneficial nematodes (e.g., Steinernema) are used in biocontrol to manage pest insects.
Explanation: Both phyla have significant economic impacts, primarily negative due to parasitism, but some nematodes offer positive contributions in pest control.
13. Annelida Characteristics (15 Marks)
- General Characteristics:
- Metameric segmentation: Body divided into repeating segments, each with similar organs.
- True coelom: Fluid-filled body cavity lined by mesoderm, allowing organ development.
- Bilateral symmetry: Enhances directed movement.
- Chaetae or suckers: For locomotion (e.g., bristles in earthworms, suckers in leeches).
- Closed circulatory system: Efficient blood transport.
- Nephridia: Excretory organs in each segment.
- Nervous system: Includes a ventral nerve cord and cerebral ganglia.
- Reproduction: Hermaphroditic or dioecious, with external or internal fertilization.
Explanation: These characteristics enable annelids to thrive in diverse environments, from soil to aquatic habitats, with segmentation enhancing flexibility.
- Significance of Segmentation:
- Enhanced mobility: Segmentation allows independent movement of body parts, improving burrowing or swimming.
- Organ specialization: Each segment can develop specialized structures, increasing efficiency.
- Regeneration: Some annelids can regenerate lost segments, aiding survival.
- Redundancy: Multiple segments with similar organs reduce the impact of injury.
Explanation: Segmentation provides evolutionary advantages, allowing annelids to adapt to various ecological niches through improved movement, resilience, and specialization.
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