TS Inter 1st Year Zoology Previous Paper -1  (2024)

 

ZOOLOGY, Paper – I

(English Version)

Time: 3 Hours] [Max. Marks: 60

Note: Read the following instructions carefully:

(i) Answer all the questions of Section A. Answer ANY SIX questions out of eight in Section B and answer ANY TWO questions out of three in Section C.(ii) In Section A, questions from Sl. Nos. 1 to 10 are of very short answer type. Each question carries TWO marks. Every answer may be limited to 5 lines. Answer all these questions at one place in the same order.

 (iii) In Section B, questions from Sl. Nos. 11 to 18 are of short answer type. Each question carries FOUR marks. Every answer may be limited to 20 lines.

(iv) In Section C, questions from Sl. Nos. 19 to 21 are of long answer type. Each question carries EIGHT marks. Every answer may be limited to 60 lines.  

(v) Draw labelled diagrams, wherever necessary for questions in Sections B and C.

SECTION A

Note: Answer ALL questions in 5 lines each.

1. What is Kinety?

Kinety refers to a specialized structure in ciliates (single-celled organisms) that consists of a group of cilia arranged in a linear row. This structure helps the organism in its locomotion and feeding processes. Kinety is typically found in the surface layer of the cell and plays a role in coordinated movement.

2. Distinguish between Embryology and Ethology.

Embryology Ethology
Embryology is the study of the development of an organism from the fertilized egg to the mature organism. Ethology is the study of animal behavior, especially in natural environments.
It focuses on the physiological, cellular, and genetic changes during an organism’s development. It focuses on the behaviors, instincts, and social interactions of animals.
Embryology deals with the early stages of life and growth of organisms. Ethology examines the evolutionary significance of behavior and animal actions.

3. What is Sesamoid bone? Give an example.

A sesamoid bone is a small, round bone that forms within a tendon. These bones help reduce friction and modify pressure, increasing the mechanical advantage of muscles.

Example: The patella (kneecap) is a prominent example of a sesamoid bone.

4. Distinguish between Amphids and Phasmids.

Amphids Phasmids
Amphids are chemosensory organs found in nematodes (roundworms), usually located near the head. Phasmids are chemosensory organs found in nematodes, located near the tail region.
They are involved in detecting chemical signals in the environment, helping with sensory perception. Phasmids also play a role in detecting chemical signals but are located at the posterior end of the body.

5. Describe a cat and a lizard on the basis of their chief nitrogenous wastes excreted.

  • Cat: A cat excretes urea as its primary nitrogenous waste. Urea is produced in the liver and excreted through the kidneys. Cats are ureotelic organisms, meaning they excrete nitrogen primarily in the form of urea.
  • Lizard: A lizard excretes uric acid as its primary nitrogenous waste. Uric acid is excreted as a paste with minimal water loss, making it more suited for terrestrial environments with limited water availability. Lizards are uricotelic organisms.

6. Define conjugation with reference to ciliates. Give two examples.

Conjugation in ciliates is a sexual process through which two ciliates exchange genetic material. During conjugation, two ciliates align, and their micronuclei undergo meiosis. They exchange haploid micronuclei, which then fuse to form a new micronucleus. This results in genetic recombination.

Examples:

  1. Paramecium
  2. Stentor

7. The eggs of Ascaris are called ‘Mammillated eggs’. Justify.

The eggs of Ascaris are called mammillated eggs because they have a characteristic, rough surface with protrusions or mammillary (bumpy) structures. These structures help in the adhesion and protection of the eggs, making them more resistant to environmental conditions and facilitating their survival in the host’s digestive system.

8. Why is the head in cockroach called hypognathus?

The head of a cockroach is called hypognathous because the mouthparts are directed downward. In a hypognathous position, the mandibles and other mouthparts point downward and are adapted for biting, chewing, and feeding on organic matter in a horizontal orientation.

9. What is storage excretion?

Storage excretion refers to the process by which waste products, particularly nitrogenous wastes, are stored in specialized cells or tissues for later excretion. These substances are not immediately eliminated but are accumulated and excreted at a later stage, often during a more favorable time. This is observed in organisms that conserve water, such as some terrestrial animals.

10. What is biological magnification?

Biological magnification (or biomagnification) is the process by which the concentration of toxic substances, such as pesticides or heavy metals, increases as they move up the food chain. These substances accumulate in the organisms at higher trophic levels, leading to higher concentrations in predators than in their prey. This phenomenon can cause significant ecological and health issues in species higher up the food chain.

SECTION B

Note: Answer ANY SIX questions in 20 lines each.

11. What is the evil quartet?

The Evil Quartet refers to the four primary factors that lead to the loss of biodiversity and the extinction of species. These are:

  1. Habitat Destruction: Loss of natural habitats due to deforestation, urbanization, and agriculture.
  2. Overexploitation: Overuse of natural resources, such as excessive hunting, fishing, and harvesting of plants, leading to population decline.
  3. Alien Invasive Species: Non-native species introduced to new environments, often outcompeting or displacing native species.
  4. Co-extinctions: The extinction of one species causing the extinction of another, often due to a dependency relationship (e.g., parasites or mutualistic relationships).

12. Describe the structure of a skeletal muscle.

The structure of a skeletal muscle includes:

  1. Muscle Fibers: Long, cylindrical cells that make up the muscle, each containing many nuclei. These fibers are striated due to the arrangement of myofilaments.
  2. Myofibrils: Small thread-like structures within muscle fibers. Myofibrils are composed of repeating units called sarcomeres, which are the basic functional units of muscle contraction.
  3. Sarcomere: The repeating structural unit of a myofibril, made up of thick (myosin) and thin (actin) filaments that slide past each other during contraction.
  4. Connective Tissue: The muscle is encased by layers of connective tissue:
    • Endomysium surrounds individual muscle fibers.
    • Perimysium surrounds muscle fiber bundles (fascicles).
    • Epimysium surrounds the entire muscle.
  5. Tendons: Muscles are connected to bones via tendons, which allow for the transfer of force and movement.

13. Write a short note on Lymph.

Lymph is a clear, colorless fluid that circulates through the lymphatic system, which is part of the circulatory and immune systems. Lymph is similar to blood plasma but contains fewer proteins. It has several key functions:

  1. Immune Defense: Lymph carries white blood cells (lymphocytes), which help fight infections.
  2. Fluid Balance: It returns excess tissue fluid to the bloodstream, preventing fluid buildup in tissues (edema).
  3. Nutrient Transport: Lymph transports fatty acids and other nutrients absorbed from the digestive system, especially from the intestines.

Lymph is filtered through lymph nodes, which play a role in immune surveillance and filtering out harmful particles.

14. Mention the general characters of Arachnida.

The Arachnida class includes spiders, scorpions, ticks, and mites. General characteristics of arachnids are:

  1. Body Segmentation: The body is divided into two main parts: the cephalothorax (head and thorax fused) and the abdomen.
  2. Number of Legs: They have eight legs, unlike insects, which have six.
  3. Antennae: Arachnids lack antennae.
  4. Respiration: They have book lungs or tracheae for respiration.
  5. Mouthparts: Specialized mouthparts, such as chelicerae, used for feeding and capturing prey.
  6. Exoskeleton: A tough exoskeleton made of chitin for protection and support.
  7. Reproduction: Arachnids often reproduce sexually, and some species exhibit complex courtship behaviors.

15. Describe the structure of the heart of a frog.

The frog heart is tri-chambered, consisting of:

  1. Two Atriums:
    • The right atrium receives deoxygenated blood from the body.
    • The left atrium receives oxygenated blood from the lungs.
  2. One Ventricle:
    • The ventricle pumps blood to both the lungs and the rest of the body. Although oxygenated and deoxygenated blood mix in the ventricle, the design helps minimize mixing.
  3. Sinus Venosus: A chamber that collects deoxygenated blood from the body and sends it to the right atrium.
  4. Conus Arteriosus: A structure that directs blood to the pulmonary and systemic circulations.

This arrangement ensures some separation of oxygenated and deoxygenated blood, though not as completely as in mammals.

16. Describe the process of transverse binary fission in Paramecium.

Transverse binary fission in Paramecium is a form of asexual reproduction. The steps are:

  1. Preparation: The Paramecium cell grows and the micronucleus undergoes mitotic division, while the macronucleus elongates.
  2. Division of Cytoplasm: The cell’s cytoplasm begins to divide transversely (across the middle) into two parts.
  3. Nuclear Division: The macronucleus divides into two and one micronucleus divides to form two daughter nuclei.
  4. Formation of Two Daughter Cells: Each new cell gets a complete set of organelles, and the cell splits into two genetically identical daughter cells.

Transverse binary fission is an efficient method of reproduction, allowing Paramecium to rapidly proliferate in suitable environments.

17. “Prevention is better than cure.” Justify with regard to TDA abuse.

The saying “Prevention is better than cure” emphasizes the importance of taking proactive measures to avoid harm rather than trying to solve a problem once it occurs. In the context of TDA (Tobacco and Alcohol) abuse, the following justifications can be made:

  1. Health Risks: Tobacco and alcohol abuse cause serious health issues, such as cancer, liver diseases, and cardiovascular problems. Prevention reduces the risk of these long-term and often irreversible effects.
  2. Cost of Treatment: Treating diseases caused by TDA abuse can be expensive and require lifelong medical attention. Prevention is more cost-effective for both individuals and healthcare systems.
  3. Better Quality of Life: Preventing TDA abuse helps individuals maintain a better quality of life by avoiding addiction, improving mental and physical health, and reducing the likelihood of premature death.
  4. Social and Economic Impact: Preventing abuse can reduce the economic burden on society due to healthcare costs and loss of productivity.

18. Discuss the various types of adaptations in freshwater animals.

Freshwater animals have developed various adaptations to survive in environments where water is hypotonic (less concentrated in solutes than the animal’s body fluids). Key adaptations include:

  1. Osmoregulation: Freshwater animals must maintain the balance of water and salts in their bodies. They have specialized excretory systems (like kidneys) that help expel excess water and conserve salts.
  2. Excretion of Dilute Urine: They excrete large volumes of highly diluted urine to eliminate excess water while conserving essential ions.
  3. Behavioral Adaptations: Many freshwater animals are adapted to seek shelter in areas with low water flow or deeper areas to avoid stress from fluctuating environmental conditions.
  4. Protective Body Coatings: Some animals, like fish, have mucous layers on their skin to prevent excessive water intake and to protect from osmotic imbalance.
  5. Efficient Respiratory Systems: Some species have specialized gills that help in oxygen absorption from water, even in low-oxygen environments.

SECTION C

Note: Answer ANY TWO questions in 60 lines each.

19. Describe the life-cycle of Plasmodium vivax in man.

Plasmodium vivax is a protozoan parasite that causes malaria in humans. The life cycle of Plasmodium vivax alternates between a human host and an Anopheles mosquito (the vector).

Stages in the Human Host:

  1. Sporozoite Stage (Infection):
    • The cycle begins when an infected female Anopheles mosquito bites a human to take a blood meal.
    • During this process, sporozoites, the infective form of the parasite, are injected into the human bloodstream.
    • These sporozoites travel through the blood to the liver, where they infect liver cells.
  2. Liver Stage (Exoerythrocytic Cycle):
    • In the liver, the sporozoites infect hepatocytes (liver cells), where they undergo asexual reproduction.
    • After several rounds of division, the liver cells rupture, releasing merozoites into the bloodstream. This marks the transition to the next stage of the cycle.
  3. Blood Stage (Erythrocytic Cycle):
    • The merozoites enter red blood cells (RBCs), where they undergo further asexual reproduction.
    • Inside the RBCs, the merozoites mature into trophozoites (feeding forms), which then divide into schizonts.
    • Schizonts mature and rupture the RBCs, releasing more merozoites into the bloodstream, which infect new RBCs.
    • This cyclical process of RBC infection and rupture is responsible for the symptoms of malaria, such as fever, chills, and anemia.
    • Some merozoites develop into gametocytes, which are the sexual forms of the parasite.

Stages in the Anopheles Mosquito:

  1. Gametocyte Stage (Sexual Reproduction):
    • When a mosquito bites an infected human, it ingests gametocytes (the sexual forms of the parasite) along with the blood.
    • Inside the mosquito’s stomach, the gametocytes mature into male and female gametes.
    • Fertilization occurs between the male and female gametes to form a zygote, which then develops into an ookinete.
  2. Sporozoite Stage in the Mosquito:
    • The ookinete penetrates the mosquito’s midgut wall and forms an oocyst. Inside the oocyst, thousands of sporozoites are produced.
    • The oocyst bursts, releasing the sporozoites into the mosquito’s body cavity, where they travel to the salivary glands.
    • When the mosquito bites another human, it injects these sporozoites, thus completing the cycle.

This life cycle of Plasmodium vivax involves both asexual reproduction in the human host and sexual reproduction in the mosquito, causing the transmission of malaria.

20. Describe the digestive system of cockroach with the help of a neat labelled diagram.

The digestive system of a cockroach consists of several specialized regions that help in the breakdown of food and absorption of nutrients. The digestive system is divided into three main sections: the foregut, the midgut, and the hindgut.

1. Foregut:

  • Mouth: The mouth of the cockroach is equipped with mandibles and maxillae for biting and grinding food.
  • Salivary Glands: These glands produce saliva that contains enzymes for the breakdown of food.
  • Pharynx: A muscular structure that helps in the passage of food from the mouth to the esophagus.
  • Esophagus: A tube-like structure that connects the pharynx to the crop.
  • Crop: A temporary storage organ where food is held before passing to the gizzard.
  • Gizzard: A thick muscular region that grinds and triturates the food, often aided by ingested grit or sand.

2. Midgut:

  • Proventriculus: A valve that controls the movement of food from the gizzard to the midgut.
  • Stomach: In the midgut, digestion continues, and enzymes from the stomach break down proteins, fats, and carbohydrates.
  • Hepatic Cells: These cells secrete digestive enzymes and play a role in the breakdown of food.
  • Mesenteric Folds: These are folds that contain digestive glands to help further break down the food.

3. Hindgut:

  • Malpighian Tubules: These are excretory structures that filter waste products from the blood, such as nitrogenous wastes.
  • Ileum: This section absorbs the nutrients from digested food.
  • Colon: A long tubular section where water and salts are absorbed.
  • Rectum: The final portion of the hindgut, where undigested food and waste products are stored before being expelled from the body.
  • Anus: The waste is excreted through the anus after passing through the rectum.

Labelled Diagram of the Cockroach Digestive System:

A typical diagram would have the following labelled parts:

  • Mouth
  • Pharynx
  • Esophagus
  • Crop
  • Gizzard
  • Proventriculus
  • Stomach
  • Ileum
  • Malpighian Tubules
  • Rectum
  • Anus

21. Describe different types of food chains that exist in an ecosystem.

A food chain is a linear sequence of organisms through which energy and nutrients pass as one organism consumes another. In an ecosystem, different types of food chains exist, including:

1. Grazing Food Chain:

  • This type of food chain begins with green plants (producers) that capture solar energy through photosynthesis.
  • Herbivores (primary consumers) feed on the producers, and carnivores (secondary consumers) feed on herbivores.
  • Example: Grass → Grasshopper → Frog → Snake → Hawk.
  • Energy flows from plants to herbivores and then to predators.

2. Detritus Food Chain:

  • This type of food chain is based on the consumption of dead organic matter (detritus), such as decaying plants and animals.
  • Decomposers (bacteria, fungi) break down dead organic material into simpler compounds, which are then consumed by detritivores (earthworms, beetles).
  • Example: Dead leaves → Earthworm → Bird → Hawk.
  • Energy flows through the decomposition of organic matter and its consumption by detritivores.

3. Parasitic Food Chain:

  • In this type of food chain, energy is transferred through parasitic relationships, where one organism (the parasite) feeds on another organism (the host), often without killing it.
  • Example: Sheep → Tick → Bird → Hawk.
  • The parasite derives nutrition from the host, usually without immediate harm to it.

4. Microbial Food Chain:

  • This food chain consists of microorganisms that break down organic matter into simpler compounds, such as bacteria and fungi.
  • Microbes serve as the primary producers, and larger organisms feed on them.
  • Example: Bacteria → Protozoa → Small Invertebrates → Fish.
  • This is an important food chain in ecosystems like soil or aquatic environments.

5. Hybrid Food Chain:

  • This food chain is a combination of grazing and detritus food chains. It may involve both producers being consumed directly and decomposers breaking down dead organisms.
  • Example: Grass → Grasshopper → Frog → Dead Frog → Bacteria.

These food chains are interconnected in an ecosystem to form a food web, which is a more complex network of feeding relationships.