1Which of the following terms describes the type of metamorphosis found in silverfish (Order Thysanura), where the young look exactly like adults except for size and sexual maturity?
A.Hemimetabolous
B.Ametabolous
C.Holometabolous
D.Paurometabolous
Correct Answer: Ametabolous
Explanation:Ametabolous development refers to 'no metamorphosis'. The insect hatches from the egg looking like a miniature adult and simply grows larger through molts. This is characteristic of primitive wingless insects like silverfish.
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2Which endocrine gland is responsible for the secretion of the Juvenile Hormone (JH)?
A.Prothoracic glands
B.Corpora cardiaca
C.Corpora allata
D.Neurosecretory cells
Correct Answer: Corpora allata
Explanation:The corpora allata are paired endocrine glands located behind the brain that secrete Juvenile Hormone, which regulates metamorphosis and reproduction.
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3In the context of insect development, what is diapause?
A.The process of shedding the exoskeleton
B.A period of suspended development and physiological arrest
C.The rapid growth phase of the larva
D.The transformation from pupa to adult
Correct Answer: A period of suspended development and physiological arrest
Explanation:Diapause is a genetically determined state of arrested development or suspended animation, usually triggered by environmental cues like photoperiod or temperature, to survive unfavorable conditions.
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4What type of larvae are characterized by having three pairs of thoracic legs but no abdominal prolegs, often found in beetles?
A.Polypod
B.Oligopod
C.Apodous
D.Protopod
Correct Answer: Oligopod
Explanation:Oligopod larvae have well-developed thoracic legs but lack abdominal prolegs. Examples include campodeiform and scarabaeiform larvae found in many Coleoptera.
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5Which type of pupa has its appendages firmly glued to the body wall, common in Lepidoptera (butterflies and moths)?
A.Exarate
B.Coarctate
C.Obtect
D.Decticous
Correct Answer: Obtect
Explanation:In obtect pupae, the appendages (legs, wings, antennae) are cemented to the body wall. A common example is the chrysalis of a butterfly.
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6The insect digestive system is divided into three main regions. Which region is lined with cuticle and is primarily responsible for ingestion, storage, and grinding of food?
A.Stomodeum (Foregut)
B.Mesenteron (Midgut)
C.Proctodeum (Hindgut)
D.Haemocoel
Correct Answer: Stomodeum (Foregut)
Explanation:The Stomodeum (foregut) is of ectodermal origin and lined with intima (cuticle). It includes the pharynx, oesophagus, crop, and proventriculus.
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7What is the primary function of the peritrophic membrane in the insect midgut?
A.To secrete digestive enzymes
B.To grind solid food particles
C.To protect the midgut epithelium from abrasion and pathogens
D.To absorb water from feces
Correct Answer: To protect the midgut epithelium from abrasion and pathogens
Explanation:The peritrophic membrane is a mesh-like structure secreted in the midgut that envelopes the food bolus, protecting the delicate epithelial cells from mechanical damage and pathogens while allowing enzyme/nutrient transport.
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8Which structure in the alimentary canal of fluid-feeding insects (like Homopterans) allows excess water to bypass the absorptive midgut to concentrate nutrients?
A.Gastric caeca
B.Filter chamber
C.Rectal pads
D.Proventriculus
Correct Answer: Filter chamber
Explanation:The filter chamber is a modification where the anterior midgut and hindgut are closely opposed or enclosed in a sheath, allowing water to bypass the main absorptive section of the midgut to prevent dilution of enzymes and concentrate nutrients.
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9The insect circulatory system is described as 'open'. What is the name of the body cavity filled with haemolymph?
A.Coelom
B.Haemocoel
C.Pseudocoelom
D.Lumen
Correct Answer: Haemocoel
Explanation:Insects have an open circulatory system where internal organs are bathed in a fluid called haemolymph within a cavity called the haemocoel.
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10What are the lateral openings in the dorsal vessel (heart) through which haemolymph enters?
A.Spiracles
B.Taenidia
C.Ostia
D.Alary pores
Correct Answer: Ostia
Explanation:Ostia are slit-like openings in the heart wall that allow haemolymph to flow from the haemocoel into the dorsal vessel.
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11Which muscles are responsible for supporting the dorsal vessel and aiding in the flow of haemolymph?
A.Alary muscles
B.Longitudinal muscles
C.Dorso-ventral muscles
D.Visceral muscles
Correct Answer: Alary muscles
Explanation:Alary muscles are wing-shaped muscles attached to the dorsal diaphragm that support the heart and assist in diastole (expansion) to intake haemolymph.
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12What is the primary nitrogenous waste product excreted by terrestrial insects to conserve water?
A.Ammonia
B.Urea
C.Uric acid
D.Creatinine
Correct Answer: Uric acid
Explanation:Terrestrial insects are uricotelic; they excrete uric acid, which is insoluble in water and relatively non-toxic, allowing them to conserve water.
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13Which organs are the primary excretory structures in insects, functioning similarly to kidneys?
A.Rectal pads
B.Malpighian tubules
C.Salivary glands
D.Oenocytes
Correct Answer: Malpighian tubules
Explanation:Malpighian tubules are blind-ending tubes floating in the haemolymph that extract nitrogenous wastes and empty them into the hindgut.
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14In the cryptonephridial system found in some beetles and moth larvae, the distal ends of the Malpighian tubules are closely associated with which organ?
A.Crop
B.Ventriculus
C.Rectum
D.Heart
Correct Answer: Rectum
Explanation:In the cryptonephridial system, the ends of the Malpighian tubules are embedded in the rectal wall to efficiently recycle water and ions from the feces, crucial for insects in dry environments.
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15The external openings of the tracheal system found on the pleuron of the thorax and abdomen are called:
A.Ostia
B.Spiracles
C.Tracheoles
D.Micropyles
Correct Answer: Spiracles
Explanation:Spiracles are the valved openings on the exoskeleton that allow air to enter the tracheal system.
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16What keeps the tracheal tubes from collapsing under pressure?
A.Chitinous intima
B.Taenidia
C.Epidermis
D.Basement membrane
Correct Answer: Taenidia
Explanation:Taenidia are spiral thickenings of the cuticle (intima) lining the tracheae that prevent them from collapsing.
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17Which part of the respiratory system acts as the direct site of gas exchange with tissues?
A.Trachea
B.Spiracle
C.Tracheole
D.Air sac
Correct Answer: Tracheole
Explanation:Tracheoles are the finest branches of the tracheal system (less than 1 micron diameter), which contact individual cells and are the site of gas exchange.
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18Aquatic insects that carry a permanent film of air held by hydrofuge hairs for respiration utilize a mechanism known as:
A.Tracheal gills
B.Rectal gills
C.Plastron respiration
D.Cuticular respiration
Correct Answer: Plastron respiration
Explanation:Plastron respiration involves a physical gill (a thin film of air) held by hydrophobic hairs, which does not need to be replenished at the surface as oxygen diffuses into it from the water.
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19The basic functional unit of the insect nervous system is the:
A.Neuron
B.Ganglion
C.Axon
D.Synapse
Correct Answer: Neuron
Explanation:The neuron (nerve cell) is the fundamental structural and functional unit of the nervous system.
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20The insect brain (supraesophageal ganglion) consists of three fused ganglia. Which part innervates the eyes?
A.Protocerebrum
B.Deutocerebrum
C.Tritocerebrum
D.Suboesophageal ganglion
Correct Answer: Protocerebrum
Explanation:The Protocerebrum is the largest and most anterior part of the brain, responsible for innervating the compound eyes and ocelli.
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21Which part of the insect brain innervates the antennae?
A.Protocerebrum
B.Deutocerebrum
C.Tritocerebrum
D.Suboesophageal ganglion
Correct Answer: Deutocerebrum
Explanation:The Deutocerebrum contains the antennal lobes and processes sensory information from the antennae.
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22The Visceral Nervous System (or Stomatogastric Nervous System) primarily controls:
A.Flight muscles
B.Sensory perception
C.The gut, heart, and reproductive organs
D.Leg movements
Correct Answer: The gut, heart, and reproductive organs
Explanation:The visceral nervous system regulates the involuntary motions of internal organs such as the anterior gut, dorsal vessel, and tracheal system.
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23Which hormone triggers the molting process by stimulating the separation of the old cuticle?
A.Juvenile Hormone
B.Ecdysone
C.Bursicon
D.Eclosion hormone
Correct Answer: Ecdysone
Explanation:Ecdysone (secreted by prothoracic glands) initiates the molting process (ecdysis) and differentiation of tissues.
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24Which neurohormone is responsible for the tanning and hardening (sclerotization) of the new cuticle after molting?
A.PTTH
B.Allatostatin
C.Bursicon
D.Ecdysteroid
Correct Answer: Bursicon
Explanation:Bursicon is a neurohormone that mediates the tanning (sclerotization) and mechanical expansion of the wings and cuticle immediately after ecdysis.
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25In the male reproductive system, sperm is stored in the:
A.Testis
B.Vas deferens
C.Seminal vesicle
D.Ejaculatory duct
Correct Answer: Seminal vesicle
Explanation:Sperm produced in the testes travel through the vas deferens to the seminal vesicles, where they are stored until copulation.
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26What is the function of the spermatheca in female insects?
A.To produce eggs
B.To store sperm after mating
C.To secrete adhesive for eggs
D.To digest sperm for nutrition
Correct Answer: To store sperm after mating
Explanation:The spermatheca is a specialized organ in the female reproductive tract that stores sperm received from the male, sometimes for the duration of the insect's life, allowing fertilization to occur long after mating.
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27Which type of ovariole lacks nutritive cells (nurse cells), with the oocyte obtaining nutrients solely from the follicular epithelium?
A.Panoistic
B.Polytrophic
C.Acrotrophic
D.Telotrophic
Correct Answer: Panoistic
Explanation:Panoistic ovarioles lack specialized nurse cells (trophocytes). All cells in the germarium develop into oocytes. Examples include Odonata and Orthoptera.
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28A form of asexual reproduction where the egg develops into a new individual without fertilization is called:
A.Viviparity
B.Parthenogenesis
C.Polyembryony
D.Paedogenesis
Correct Answer: Parthenogenesis
Explanation:Parthenogenesis is the development of an embryo from an unfertilized egg. It is common in aphids and bees.
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29What is Arrhenotoky?
A.Production of only females from unfertilized eggs
B.Production of only males from unfertilized eggs
C.Production of both sexes from unfertilized eggs
D.Reproduction by immature larvae
Correct Answer: Production of only males from unfertilized eggs
Explanation:Arrhenotoky is a form of parthenogenesis where unfertilized eggs develop into haploid males (e.g., drones in honey bees), while fertilized eggs become diploid females.
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30The reproduction phenomenon where a single egg divides to produce multiple embryos (often in parasitic wasps) is known as:
A.Paedogenesis
B.Polyembryony
C.Ovoviviparity
D.Hermaphroditism
Correct Answer: Polyembryony
Explanation:Polyembryony is the formation of two or more embryos from a single fertilized egg. It is a strategy often used by parasitoid Hymenoptera to maximize offspring from a single host.
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31Which term describes insects that give birth to live larvae or nymphs instead of laying eggs?
A.Oviparous
B.Viviparous
C.Ovoviviparous
D.Parthenogenetic
Correct Answer: Viviparous
Explanation:Viviparity is the condition of giving birth to living young rather than laying eggs. Aphids are a common example during summer generations.
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32Paedogenesis is defined as:
A.Reproduction by sexually mature adults
B.Reproduction by immature stages (larvae or pupae)
C.Reproduction involving two males
D.Giving birth to pupae
Correct Answer: Reproduction by immature stages (larvae or pupae)
Explanation:Paedogenesis is a rare form of reproduction where the ovaries mature and produce offspring while the insect is still in a larval or pupal stage (e.g., gall midges).
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33The individual functional unit of a compound eye is called a(n):
A.Ocellus
B.Ommatidium
C.Rhabdom
D.Cornea
Correct Answer: Ommatidium
Explanation:The compound eye is composed of thousands of repeating hexagonal units called ommatidia, each with its own lens and photoreceptor cells.
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34What is the specific function of the Johnston’s organ located in the pedicel of the antenna?
Explanation:Johnston's organ detects motion in the antennal flagellum. It senses flight speed (air speed) in many insects and sound (vibrations) in male mosquitoes.
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35Tympanal organs are responsible for:
A.Vision
B.Taste
C.Hearing
D.Balance
Correct Answer: Hearing
Explanation:Tympanal organs are the 'ears' of insects, consisting of a thin membrane (tympanum) stretched over a frame, used to detect sound waves.
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36Simple eyes found in holometabolous larvae (like caterpillars) are called:
A.Dorsal ocelli
B.Stemmata
C.Ommatidia
D.Pseudopods
Correct Answer: Stemmata
Explanation:Stemmata (singular: stemma), or lateral ocelli, are the visual organs of holometabolous larvae. They usually provide poor image resolution compared to compound eyes.
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37Scolopidia are the fundamental units of which type of sensory organ?
A.Chemoreceptors
B.Mechanoreceptors
C.Photoreceptors
D.Hygroreceptors
Correct Answer: Mechanoreceptors
Explanation:Scolopidia are the bipolar neuron units found in chordotonal organs (mechanoreceptors) that detect stretching, vibration, or pressure.
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38Where are gustatory (taste) receptors primarily located in butterflies?
A.Antennae
B.Tarsi (feet)
C.Wings
D.Abdomen
Correct Answer: Tarsi (feet)
Explanation:Many butterflies and flies have taste receptors on their tarsi to detect host plants or food sources upon landing.
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39The Proventriculus (gizzard) is most highly developed in insects that eat:
A.Liquid nectar
B.Solid food
C.Blood
D.Plant sap
Correct Answer: Solid food
Explanation:The proventriculus contains sclerotized teeth or plates used to grind solid food before it enters the midgut. It is prominent in chewing insects like Orthoptera and Coleoptera.
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40What is the function of the rectal pads or papillae?
A.Secretion of pheromones
B.Reabsorption of water and salts
C.Digestion of cellulose
D.Storage of waste
Correct Answer: Reabsorption of water and salts
Explanation:Rectal pads act to recover water, salts, and amino acids from the feces before excretion, playing a vital role in osmoregulation.
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41Which type of larvae is legless and often has a reduced head capsule, typical of house flies?
A.Scarabaeiform
B.Vermiform
C.Campodeiform
D.Elateriform
Correct Answer: Vermiform
Explanation:Vermiform larvae are worm-like, legless (apodous), and often have reduced heads (maggots). They are characteristic of specialized Diptera.
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42A Coarctate pupa is enclosed within:
A.A silken cocoon
B.The last larval skin (puparium)
C.Leaves tied together
D.An earthen cell
Correct Answer: The last larval skin (puparium)
Explanation:In coarctate pupae (found in higher Diptera), the pupa remains enclosed inside the hardened exuviae of the last larval instar, known as the puparium.
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43The process of breakdown of larval tissues during metamorphosis is called:
A.Histogenesis
B.Histolysis
C.Ecdysis
D.Sclerotization
Correct Answer: Histolysis
Explanation:Histolysis is the breakdown of larval tissues into material that can be used to build adult structures. The building of new tissues is called Histogenesis.
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44Which cells in the insect haemolymph are responsible for encapsulation of large parasites?
A.Prohemocytes
B.Plasmatocytes/Lamellocytes
C.Oenocytes
D.Trophocytes
Correct Answer: Plasmatocytes/Lamellocytes
Explanation:Haemocytes, specifically plasmatocytes and lamellocytes, aggregate around large foreign bodies (like parasitoid eggs) to form a capsule.
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45Neurosecretory cells in the brain produce PTTH (Prothoracicotropic Hormone). What is its target organ?
A.Corpora Allata
B.Prothoracic Glands
C.Ovaries
D.Midgut
Correct Answer: Prothoracic Glands
Explanation:PTTH stimulates the prothoracic glands to secrete ecdysone.
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46In the female reproductive system, the accessory glands often secrete a substance to protect eggs. In cockroaches and mantids, this forms a(n):
A.Puparium
B.Ootheca
C.Spermatophore
D.Chorion
Correct Answer: Ootheca
Explanation:The colleterial (accessory) glands secrete substances that harden to form an ootheca (egg case) protecting the eggs.
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47Campodeiform larvae are:
A.Active, predaceous with long legs
B.Sluggish, C-shaped grubs
C.Legless maggots
D.Wireworms with hard bodies
Correct Answer: Active, predaceous with long legs
Explanation:Campodeiform larvae are active, elongated, and flattened with well-developed legs and antennae, typical of predaceous beetles like Coccinellids or Neuroptera.
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48What is the function of the intima in the tracheal system?
A.Gas exchange
B.Structural lining
C.Secretion of mucus
D.Filtering dust
Correct Answer: Structural lining
Explanation:The intima is the cuticular lining of the tracheae, continuous with the external exoskeleton, providing structure.
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49The distinct light-refracting structure in an ommatidium consisting of a lens and a crystalline cone is the:
A.Dioptric apparatus
B.Receptor apparatus
C.Pigment cells
D.Optic nerve
Correct Answer: Dioptric apparatus
Explanation:The dioptric apparatus focuses light onto the photoreceptors. It includes the corneal lens and the crystalline cone.
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50An insect with an Exarate pupa has:
A.Appendages free from the body
B.Appendages glued to the body
C.A puparium
D.No pupal stage
Correct Answer: Appendages free from the body
Explanation:Exarate pupae have appendages (legs, wings, antennae) that are free and not cemented to the body wall. Common in beetles (Coleoptera) and bees (Hymenoptera).