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Tamil Nadu HSE First Year Zoology study materials
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Tamil Nadu HSE First Year Zoology practice questions

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Question 1Diversity of Living World and Animal Kingdom

In the five-kingdom classification proposed by R. H. Whittaker, which kingdom includes unicellular eukaryotes such as Euglena and Paramecium that show both plant-like and animal-like features?

  1. Kingdom Animalia
  2. Kingdom Protista Correct answer.
  3. Kingdom Fungi
  4. Kingdom Monera

Explanation

Whittaker's five-kingdom system places all unicellular eukaryotes in Kingdom Protista, a group defined mainly by being eukaryotic and largely unicellular rather than by a single mode of nutrition. Euglena photosynthesises like a plant yet moves and lacks a cell wall, and Paramecium is a heterotrophic ciliate, so both are protists. Monera covers prokaryotes and Fungi covers absorptive multicellular forms.

Question 2Diversity of Living World and Animal Kingdom

Which criterion is used in the three-domain system of Carl Woese to separate the Archaea from the Bacteria?

  1. Type of locomotory organelle present
  2. Presence of chlorophyll a in the photosystems
  3. Comparison of ribosomal RNA sequences Correct answer.
  4. Number of chromosomes in the cell

Explanation

Woese compared sequences of small-subunit ribosomal RNA and found that Archaea differ from Bacteria as profoundly as both differ from Eukarya. This molecular evidence, not morphology, produced the three domains: Archaea, Bacteria and Eukarya. Features such as chlorophyll type or chromosome number are not the basis of this division.

Question 3Diversity of Living World and Animal Kingdom

A student observes a preserved specimen with a cartilaginous skeleton, placoid scales, ventral mouth and gill slits without an operculum. To which group does the specimen belong?

  1. Amphibia
  2. Cyclostomata
  3. Osteichthyes
  4. Chondrichthyes Correct answer.

Explanation

Chondrichthyes are characterised by a cartilaginous endoskeleton, placoid scales, a ventrally placed mouth and gill slits that are not covered by an operculum. Sharks, rays and skates show this combination. Osteichthyes have bony skeletons and an operculum, while cyclostomes lack jaws and scales entirely.

Question 4Diversity of Living World and Animal Kingdom

Which feature of the phylum Porifera is correctly described?

  1. The body wall contains choanocytes that create water currents Correct answer.
  2. Digestion is extracellular within a complete alimentary canal
  3. Water enters through the osculum and leaves through ostia
  4. The nervous system consists of a dorsal nerve cord

Explanation

Sponges have a body wall perforated by ostia and lined internally by flagellated collar cells called choanocytes, whose beating drives water through the canal system. Water enters through ostia and exits through the osculum, the reverse of option one. Sponges lack a true gut and any organised nervous system.

Question 5Diversity of Living World and Animal Kingdom

In the phylum Coelenterata, the cells that bear nematocysts and are used for defence and capture of prey are called

  1. Nephridia
  2. Flame cells
  3. Cnidoblasts Correct answer.
  4. Collar cells

Explanation

Cnidoblasts, also called nematoblasts, are specialised epidermal cells of coelenterates that contain the stinging organelle called a nematocyst. Discharge of the nematocyst paralyses prey and assists in defence. Collar cells occur in sponges, flame cells in flatworms and nephridia in annelids.

Question 6Diversity of Living World and Animal Kingdom

Which combination of features is characteristic of the phylum Platyhelminthes?

  1. Coelomate, segmented body, with closed circulation
  2. Acoelomate, bilaterally symmetrical, with flame cells for excretion Correct answer.
  3. Pseudocoelomate, radially symmetrical, with a complete gut
  4. Coelomate, jointed appendages, with Malpighian tubules

Explanation

Flatworms are triploblastic acoelomates with bilateral symmetry and dorsoventral flattening. Because they have no coelom, excretion is handled by protonephridia ending in flame cells, and the gut, when present, is incomplete. This suite of characters separates them from pseudocoelomates and true coelomates.

Question 7Diversity of Living World and Animal Kingdom

The phylum Aschelminthes is distinguished from Platyhelminthes mainly by the presence of

  1. True segmentation and setae
  2. A water vascular system and tube feet
  3. A mantle and a radula
  4. A pseudocoelom and a complete digestive tract Correct answer.

Explanation

Aschelminthes, or roundworms, possess a body cavity that is not lined by mesoderm and is therefore called a pseudocoelom, and their digestive tract runs from mouth to anus. Flatworms lack a body cavity and usually have an incomplete gut. Segmentation, the water vascular system and the mantle-radula complex belong to other phyla.

Question 8Diversity of Living World and Animal Kingdom

In the phylum Annelida, the structure that helps in locomotion by anchoring the body and that is absent in leeches is the

  1. Nephridium
  2. Seta Correct answer.
  3. Parapodium
  4. Clitellum

Explanation

Setae are chitinous bristles secreted by epidermal cells that grip the substratum during peristaltic crawling, and they are absent in leeches, which move by suckers. Parapodia are fleshy lateral outgrowths of polychaetes, the clitellum is a reproductive glandular band, and nephridia are excretory organs.

Question 9Diversity of Living World and Animal Kingdom

Which feature is characteristic of the phylum Arthropoda and helps explain its success as the largest animal phylum?

  1. A chitinous exoskeleton with jointed appendages and moulting Correct answer.
  2. A water vascular system with ambulacral grooves
  3. A calcareous shell secreted by a mantle
  4. A notochord present throughout life

Explanation

Arthropods are protected by a chitinous exoskeleton and bear jointed appendages specialised for walking, feeding, sensing and reproduction. Because the exoskeleton restricts growth, it must be shed periodically by moulting or ecdysis. This body plan, together with tracheal or other efficient respiratory systems, underlies their enormous diversity.

Question 10Diversity of Living World and Animal Kingdom

The excretory organs of most insects are

  1. Nephridia
  2. Malpighian tubules Correct answer.
  3. Flame cells
  4. Green glands

Explanation

Malpighian tubules are fine blind-ended tubules opening into the alimentary canal at the junction of midgut and hindgut; they absorb nitrogenous waste from the haemolymph and pass it into the gut for elimination. Nephridia are annelid organs, flame cells are flatworm organs, and green or antennal glands occur in crustaceans such as prawns.

Question 11Diversity of Living World and Animal Kingdom

A soft-bodied animal with a ventral muscular foot, a rasping radula and a mantle cavity is most likely to belong to which phylum?

  1. Annelida
  2. Echinodermata
  3. Arthropoda
  4. Mollusca Correct answer.

Explanation

The muscular foot, the radula used for scraping food, and the mantle enclosing the mantle cavity that houses the gills are the classic molluscan features. The mantle also secretes the shell in shelled forms. Annelids and arthropods are segmented with different body plans, and echinoderms show radial symmetry with a water vascular system.

Question 12Diversity of Living World and Animal Kingdom

The water vascular system of echinoderms is important mainly for

  1. Production of nematocysts
  2. Secretion of the calcareous shell
  3. Excretion through Malpighian tubules
  4. Respiration, locomotion and food capture through tube feet Correct answer.

Explanation

The water vascular system is a network of canals filled with seawater that extends into tube feet. Hydraulic pressure and muscular action extend and retract the tube feet, enabling slow locomotion, and the same system assists respiration, feeding and sensory reception. Echinoderms have a calcareous endoskeleton rather than a secreted shell.

Question 13Diversity of Living World and Animal Kingdom

Which chordate feature is present in the larval stage of a sea squirt but lost in the adult?

  1. Chitinous exoskeleton
  2. Dorsal hollow nerve cord Correct answer.
  3. Dorsal heart
  4. Open circulatory system

Explanation

Ascidians, or sea squirts, are urochordates whose free-swimming tadpole larva has a notochord and a dorsal hollow nerve cord confined to the tail. During metamorphosis into the sessile adult, the tail with these structures is resorbed. This is why the larval stage provides the chordate evidence in the group.

Question 14Diversity of Living World and Animal Kingdom

In the class Cyclostomata, the mouth is described as

  1. Ventral and suctorial, without jaws Correct answer.
  2. Bordered by placoid scales
  3. Terminal and armed with jaws
  4. Surrounded by a radula

Explanation

Cyclostomes such as Petromyzon and Myxine are jawless fishes with a circular suctorial mouth that is ventral in position and armed with horny teeth for rasping flesh. The absence of jaws is a defining feature of the group. Placoid scales and a radula belong to other groups.

Question 15Diversity of Living World and Animal Kingdom

Which of the following is a correct pairing of an animal with its class within the phylum Chordata?

  1. Pterophyllum - Chondrichthyes
  2. Hyla - Reptilia
  3. Exocoetus - Osteichthyes Correct answer.
  4. Neophron - Mammalia

Explanation

Exocoetus, the flying fish, is a bony fish and therefore belongs to class Osteichthyes. Pterophyllum is also a bony fish, Hyla is an amphibian, and Neophron, the vulture, is a bird. Correct class assignment depends on the skeletal, respiratory and integumentary characters of the animal.

Question 16Diversity of Living World and Animal Kingdom

Which of the following is an example of a living fossil among the vertebrates studied in the animal kingdom?

  1. Latimeria Correct answer.
  2. Aptenodytes
  3. Pavo cristatus
  4. Rana tigrina

Explanation

Latimeria, the coelacanth, is a lobe-finned fish known first from fossils and later discovered alive, so it is described as a living fossil. Rana tigrina is a common frog, Pavo cristatus is the Indian peafowl and Aptenodytes is a penguin; none of these has a comparable fossil history with a single surviving lineage.

Question 17Diversity of Living World and Animal Kingdom

Which taxonomic aid is used to identify an organism by making a choice between two mutually exclusive contrasting characters at each step?

  1. Botanical garden
  2. Biological museum
  3. Herbarium sheet
  4. Taxonomic key Correct answer.

Explanation

A taxonomic key presents pairs of contrasting statements, called a couplet, and the user selects the statement that fits the specimen, moving to the next couplet until the taxon is reached. Keys may be indented or bracketed. Herbaria, museums and gardens are collections or living repositories, not stepwise identification tools.

Question 18Diversity of Living World and Animal Kingdom

Two organisms belong to the same genus but different species. Which statement about them must be true?

  1. They have identical karyotypes
  2. They belong to different families
  3. They interbreed freely to produce fertile offspring in nature
  4. They share more recent common ancestry with each other than either does with members of another genus Correct answer.

Explanation

Genus is a lower taxonomic rank than family, so two species of the same genus are more closely related to each other than to species placed in other genera. They are distinct species and therefore do not freely interbreed to give fertile offspring, though they share many characters. Similarity of karyotype is not guaranteed.

Question 19Diversity of Living World and Animal Kingdom

Which of the following sequences correctly shows taxonomic categories from the largest to the smallest?

  1. Phylum, Class, Order, Family, Genus Correct answer.
  2. Class, Phylum, Family, Order, Genus
  3. Kingdom, Phylum, Family, Class, Order
  4. Phylum, Order, Class, Genus, Family

Explanation

The standard hierarchy descends from kingdom through phylum, class, order, family, genus to species. The sequence phylum, class, order, family, genus therefore runs correctly from larger to smaller categories. Any arrangement that places order above class, or family above class, violates the accepted order.

Question 20Diversity of Living World and Animal Kingdom

Binomial nomenclature as formalised by Linnaeus requires that the scientific name of a species consists of

  1. A family name followed by a genus name
  2. A genus name and a specific epithet, with the genus name capitalised Correct answer.
  3. A single descriptive Latin phrase
  4. Two specific epithets, both capitalised

Explanation

In binomial nomenclature the first word of the scientific name is the genus, always written with an initial capital, and the second is the specific epithet, written in lower case. Both are italicised in print or underlined in handwriting. A single polynomial phrase was the pre-Linnaean practice.

Question 21Diversity of Living World and Animal Kingdom

A species is described as having a type specimen deposited in a museum. What is the role of this type specimen?

  1. It is the permanent reference against which the identity of the species is fixed Correct answer.
  2. It is the largest specimen ever collected
  3. It is a living individual kept for breeding
  4. It is a specimen chosen only for display

Explanation

The type specimen, usually the holotype, is the permanent reference material on which the original description of a new species is based. It anchors the name so that later workers can check whether specimens belong to the same species. Types need not be the largest or the most attractive specimens, and they are preserved rather than bred.

Question 22Diversity of Living World and Animal Kingdom

In the phylum Echinodermata, the adult body plan differs from the larva in that the adult shows

  1. Spherical symmetry throughout life
  2. Pentaradial symmetry while the larva is bilaterally symmetrical Correct answer.
  3. No symmetry at all
  4. Bilateral symmetry while the larva is radial

Explanation

Echinoderm larvae are free-swimming and bilaterally symmetrical, whereas metamorphosis produces an adult with pentaradial symmetry, that is, body parts arranged in five radii. This change is a classic example of secondary radial symmetry in a bilaterally derived lineage. Sponges, by contrast, often show no fixed symmetry.

Question 23Diversity of Living World and Animal Kingdom

Which feature distinguishes the phylum Hemichordata from the true chordates?

  1. They have a water vascular system and tube feet
  2. The notochord is confined to the anterior proboscis region and the nerve cord is not truly dorsal and hollow throughout Correct answer.
  3. They possess a vertebral column
  4. They possess a post-anal tail and a dorsal hollow nerve cord

Explanation

Hemichordates such as Balanoglossus have a short notochord-like stomochord in the proboscis and a nerve cord that is not hollow and dorsal in the chordate manner. They are therefore treated as a separate phylum rather than as true chordates. A post-anal tail with a dorsal hollow nerve cord is the chordate condition, absent here.

Question 24Diversity of Living World and Animal Kingdom

Which respiratory structure is correctly matched with the animal group in which it occurs?

  1. Book lungs in scorpions Correct answer.
  2. Tracheae in earthworms
  3. Mammary glands in birds
  4. Gills in adult frogs only

Explanation

Scorpions are arachnids and breathe by book lungs, which are stacked lamellae within an invagination of the body wall. Earthworms exchange gases across the moist skin rather than by tracheae, adult frogs use lungs and skin, and mammary glands are a defining mammalian feature absent in birds.

Question 25Structural Organisation in Animals

In the earthworm, the clitellum is located in which of the following segments?

  1. Segments 26–32
  2. Segments 5–9
  3. Segments 14–16 Correct answer.
  4. Segments 17–19

Explanation

The clitellum is a thickened glandular region of the body wall that secretes the cocoon during reproduction. In Pheretima it occupies segments 14, 15 and 16, appearing as a saddle-like swelling on the dorsal side.

Question 26Structural Organisation in Animals

Which structure in the cockroach is responsible for grinding food into fine particles?

  1. Gizzard (proventriculus) Correct answer.
  2. Crop
  3. Hepatic caeca
  4. Malpighian tubules

Explanation

The foregut of the cockroach is differentiated into pharynx, oesophagus, crop and gizzard. The gizzard, or proventriculus, has a chitinous armature of six teeth that triturates food before it enters the midgut.

Question 27Structural Organisation in Animals

The body cavity of Ascaris is best described as which type?

  1. Acoelomate with solid mesenchyme
  2. True coelom lined by peritoneum
  3. Haemocoel
  4. Pseudocoelom Correct answer.

Explanation

Nematodes possess a pseudocoelom, a fluid-filled space between the body wall and the gut that is not lined by a mesodermal peritoneum. In Ascaris this cavity is filled with pseudocoelomic fluid and houses the reproductive organs.

Question 28Structural Organisation in Animals

In the frog, the structure that receives blood from the two anterior venae cavae and the posterior vena cava is the:

  1. Right auricle
  2. Conus arteriosus
  3. Sinus venosus Correct answer.
  4. Left auricle

Explanation

The sinus venosus is a thin-walled chamber into which the precaval and postcaval veins drain. It opens into the right auricle through the sinu-atrial aperture, so it is the first chamber to receive deoxygenated systemic blood.

Question 29Structural Organisation in Animals

The nephridia of the earthworm that open to the exterior through nephridiopores on the body surface are called:

  1. Septal nephridia
  2. Pharyngeal nephridia
  3. Integumentary nephridia Correct answer.
  4. Micronephridia

Explanation

Pheretima has three sets of nephridia. Integumentary nephridia lie on the inner body wall and discharge waste directly through nephridiopores, whereas septal nephridia open into the gut and pharyngeal nephridia open into the pharynx.

Question 30Structural Organisation in Animals

Which of the following correctly pairs a cockroach mouthpart with its function?

  1. Labium - piercing tissue
  2. Maxillae - holding and manipulating food Correct answer.
  3. Labrum - crushing food
  4. Mandibles - sucking nectar

Explanation

The maxillae are paired accessory mouthparts bearing lobes and palps that hold and manipulate food while the mandibles chew it. Each mouthpart in the cockroach is adapted for biting and chewing rather than sucking or piercing.

Question 31Structural Organisation in Animals

In the frog, the third eyelid that can be drawn over the eye is called the:

  1. Cornea
  2. Sclerotic coat
  3. Tympanic membrane
  4. Nictitating membrane Correct answer.

Explanation

The nictitating membrane is a transparent fold of skin that sweeps across the frog's eye to keep it moist and clean while the animal is under water. It is moved by the retractor bulbi muscle.

Question 32Structural Organisation in Animals

The blood of the earthworm is red because the plasma contains which respiratory pigment?

  1. Haemocyanin
  2. Haemerythrin
  3. Haemoglobin Correct answer.
  4. Chlorocruorin

Explanation

Earthworm blood is red because haemoglobin is dissolved in the plasma; the coelomic corpuscles are colourless. Haemoglobin has a high affinity for oxygen and is well suited to the low oxygen tension of the burrow.

Question 33Structural Organisation in Animals

A student observes that a cockroach can detect a faint air current from behind it and turn rapidly. Which receptor group makes this possible?

  1. Campaniform sensilla on the legs
  2. Compound eyes on the head
  3. Anal cerci with sensory hairs Correct answer.
  4. Antennae with Johnston's organ

Explanation

The paired anal cerci at the posterior end of the abdomen carry numerous sensory hairs that detect air-borne vibrations. This posterior detection allows the insect to turn away from an approaching predator.

Question 34Structural Organisation in Animals

In Pheretima, the spermathecae are located in which segments?

  1. 5, 6, 7 and 8 Correct answer.
  2. 9 and 10
  3. 17 and 19
  4. 14, 15 and 16

Explanation

The spermathecae are four pairs of flask-shaped receptacles lying in segments 5, 6, 7 and 8. They store sperm received from a partner during copulation and release it later to fertilise the eggs in the cocoon.

Question 35Structural Organisation in Animals

The number of Malpighian tubules in a cockroach is typically:

  1. About 10, arranged in two groups
  2. Absent, since excretion is by nephridia
  3. Two, one on each side
  4. About 100–150, arranged in six groups Correct answer.

Explanation

Periplaneta has a large number of fine Malpighian tubules, roughly 100 to 150, arranged in six tufts at the junction of the midgut and hindgut. They absorb nitrogenous waste from the haemolymph and pass it into the gut for elimination.

Question 36Structural Organisation in Animals

Which of the following features distinguishes the skeleton of the frog from that of the cockroach?

  1. The cockroach has an endoskeleton, while the frog has an exoskeleton
  2. The frog has no skull, while the cockroach has a head capsule
  3. The frog has an endoskeleton of bone and cartilage, while the cockroach has an exoskeleton of chitin Correct answer.
  4. Both possess an exoskeleton of chitin

Explanation

Frogs are vertebrates with an internal skeleton of bone and cartilage that grows with the body. Cockroaches are arthropods whose rigid chitinous exoskeleton must be shed by moulting to allow growth.

Question 37Structural Organisation in Animals

The glands of the frog skin that secrete a watery fluid to keep the skin moist are the:

  1. Sebaceous glands
  2. Ceruminous glands
  3. Mucous glands Correct answer.
  4. Poison glands

Explanation

The frog skin contains numerous mucous glands whose secretion keeps the surface moist for cutaneous respiration. Poison glands are the larger parotoid-type glands that secrete a defensive irritant.

Question 38Structural Organisation in Animals

In the earthworm, the first septal nephridium appears behind which septum?

  1. Septum 14/15
  2. Septum 15/16
  3. Septum 13/14 Correct answer.
  4. Septum 5/6

Explanation

Septal nephridia occur on both faces of the septa from 15/16 backwards, so the first one lies just behind the septum separating segments 13 and 14. The septa in front of this level lack septal nephridia.

Question 39Structural Organisation in Animals

In the cockroach, the principal nitrogenous excretory product released into the gut and voided with faeces is:

  1. Creatinine
  2. Uric acid Correct answer.
  3. Urea
  4. Ammonia

Explanation

Cockroaches are uricotelic: Malpighian tubules secrete uric acid into the hindgut, where water is reabsorbed and the acid is voided as a dry paste. Uricotely conserves water, an advantage in terrestrial insects.

Question 40Structural Organisation in Animals

Which statement about the heart of the frog is correct?

  1. It has two chambers and pumps only deoxygenated blood
  2. It has three chambers and receives mixed blood in the ventricle Correct answer.
  3. It has four chambers with complete septa
  4. It has three chambers and no sinus venosus

Explanation

The frog heart has two auricles and one ventricle, so oxygenated blood from the lungs and deoxygenated blood from the body both enter the single ventricle. The ventricle therefore pumps mixed blood, though a spiral valve in the conus arteriosus helps stream it selectively.

Question 41Structural Organisation in Animals

The chitinous teeth of the cockroach gizzard number:

  1. Twelve
  2. Six Correct answer.
  3. Eight
  4. Four

Explanation

The proventriculus bears six prominent chitinous teeth arranged radially, along with denticles, that grind food into fine particles. This armature is a key feature distinguishing the gizzard from the storage crop.

Question 42Structural Organisation in Animals

In the earthworm, the integumentary nephridia are numerous and lie attached to the inner surface of the body wall. Their functional significance is best interpreted as:

  1. They serve mainly for osmoregulation of the coelomic fluid only
  2. They store sperm before copulation
  3. They secrete the cocoon during breeding
  4. They supplement excretion and allow rapid discharge of waste directly to the exterior Correct answer.

Explanation

Integumentary nephridia are very numerous and open directly through nephridiopores on the body surface. Because their ducts are short and do not traverse septa, they can discharge waste quickly and supplement the septal and pharyngeal nephridia.

Question 43Structural Organisation in Animals

The lateral hearts of the earthworm that connect the dorsal and ventral blood vessels are located in segments:

  1. 7, 9, 12 and 13 Correct answer.
  2. 9, 10, 11 and 12
  3. 5, 6, 7 and 8
  4. 14, 15 and 16

Explanation

Pheretima has four pairs of muscular lateral hearts in segments 7, 9, 12 and 13 that pump blood from the dorsal to the ventral vessel. Segments 7 and 9 are the anterior hearts and 12 and 13 the posterior hearts.

Question 44Structural Organisation in Animals

A zoology student compares the respiratory surfaces of a frog and a cockroach. Which conclusion is most defensible?

  1. Both rely mainly on tracheae for gas exchange
  2. The frog uses gills throughout life, while the cockroach uses lungs
  3. The frog uses lungs, skin and buccal lining, while the cockroach uses tracheae opening through spiracles Correct answer.
  4. Both use the body surface alone for gas exchange

Explanation

The adult frog respires through lungs, moist skin and the buccal lining, each of which must remain vascular and damp. The cockroach instead has a tracheal system in which spiracles admit air into tubes that deliver oxygen directly to tissues.

Question 45Animal Tissues and Organ Systems

In the TN HSE Zoology classification of animal tissues, which tissue is described as having a fluid matrix called plasma and cells that are mostly separated by abundant intercellular material?

  1. Nervous tissue
  2. Connective tissue proper
  3. Epithelial tissue
  4. Blood Correct answer.

Explanation

Blood is a specialised connective tissue in which the matrix is a liquid called plasma, and the cells (RBCs, WBCs and platelets) are scattered within it rather than packed together. This fluid matrix allows transport of gases, nutrients and hormones. Epithelial and nervous tissues do not possess such a plasma matrix.

Question 46Animal Tissues and Organ Systems

The tissue lining the inner surface of the mouth and the alveoli of the lungs, which allows rapid diffusion and reduces friction, is best described as which type?

  1. Stratified squamous epithelium
  2. Simple squamous epithelium Correct answer.
  3. Ciliated columnar epithelium
  4. Glandular epithelium

Explanation

Simple squamous epithelium is a single layer of flat cells that forms thin, smooth linings such as the buccal lining and the alveolar walls. Its thinness permits quick diffusion of gases and its smooth surface reduces friction. Stratified and columnar epithelia are thicker or secretory and do not fit these sites.

Question 47Animal Tissues and Organ Systems

Which protein filaments slide over one another during muscle contraction according to the sliding filament theory studied in TN HSE Zoology?

  1. Tubulin and dynein
  2. Keratin and lamin
  3. Collagen and elastin
  4. Actin and myosin Correct answer.

Explanation

Muscle contraction occurs when thin actin filaments slide over thick myosin filaments, shortening the sarcomere. Myosin heads bind actin and use ATP to pull the filaments past each other. The other protein pairs serve structural or transport roles, not sarcomere sliding.

Question 48Animal Tissues and Organ Systems

A student observes a tissue with cells having a single long axon and many short branched dendrites, and with a prominent Nissl granule-rich cell body. This tissue is specialised mainly to do which of the following?

  1. Store fat as a reserve food
  2. Conduct impulses and integrate information Correct answer.
  3. Secrete hormones directly into blood
  4. Support and bind other tissues mechanically

Explanation

Neurons with dendrites, an axon and Nissl granules in the cyton are the units of nervous tissue, whose function is to receive, conduct and integrate impulses. Hormone secretion into blood is endocrine glandular function, fat storage is adipose tissue and mechanical support is connective tissue.

Question 49Animal Tissues and Organ Systems

Which of the following is a correct pairing of a bone of the human skull with the type of joint it makes with its neighbour?

  1. Atlas with occipital bone - cartilaginous symphysis
  2. Femur with hip bone - fibrous suture
  3. Parietal with frontal bone - pivot joint
  4. Mandible with temporal bone - hinge (synovial) joint Correct answer.

Explanation

The temporomandibular joint between the mandible and the temporal bone is a synovial hinge-type joint that permits opening and closing of the mouth. Sutures between flat skull bones are fibrous and immovable, and the atlas-occipital joint is a synovial ellipsoid joint, not a symphysis.

Question 50Animal Tissues and Organ Systems

In the human alimentary canal, the region where most chemical digestion and absorption of nutrients occurs is the

  1. Oesophagus
  2. Small intestine Correct answer.
  3. Stomach
  4. Large intestine

Explanation

The small intestine receives pancreatic juice and bile and its own intestinal juice, and its villi greatly increase surface area for absorption of digested nutrients. The stomach mainly digests protein partly, the oesophagus only conducts food and the large intestine mainly absorbs water and salts.