Morphology of Cockroach Questions in English

(D) In cockroaches,both males and females possess a pair of jointed filamentous structures called $Anal \ cerci$ arising from the $10^{th}$ segment. However,males possess an additional pair of short,thread-like anal styles arising from the $9^{th}$ sternum. These $Anal \ styles$ are absent in females. Therefore,the presence of $Anal \ styles$ is the characteristic feature that distinguishes male cockroaches from females.

(D) In cockroaches,the $anal$ $cerci$ are paired,jointed,sensory appendages located on the $10^{th}$ abdominal segment.
These structures act as sound-receptive organs,allowing the cockroach to detect vibrations in the air and ground,which helps in sensing predators or environmental changes.

(D) The compound eye of a cockroach consists of approximately $2000$ hexagonal units called $Ommatidia$ (singular: $Ommatidium$).
Each $Ommatidium$ acts as an independent visual unit that captures a small part of the image.
These units collectively form a mosaic vision,which is highly sensitive to movement.

(D) The eggs of cockroaches $(Periplaneta \text{ } americana)$ are $centrolecithal$.
In $centrolecithal$ eggs, the yolk is concentrated in the center of the egg, and the cytoplasm is restricted to the peripheral layer.
This type of egg is characteristic of most insects.

(A) Compound eyes are a characteristic feature of the phylum $Arthropoda$.
Among the given options,the cockroach ($Periplaneta$ $americana$) belongs to the class $Insecta$ of the phylum $Arthropoda$.
Insects typically possess a pair of compound eyes on the dorsal side of the head.
Chameleon is a reptile,Pila is a mollusk,and Octopus is a cephalopod mollusk; none of these possess compound eyes.

(A) Compound eyes are a characteristic feature of the phylum $Arthropoda$.
Among the given options,the cockroach ($Periplaneta$ $americana$) belongs to the class $Insecta$ under the phylum $Arthropoda$.
Therefore,it possesses compound eyes.
Chameleon is a reptile,Pila is a mollusk,and Octopus is a cephalopod mollusk; none of these possess compound eyes.

(D) Let us analyze each option:
$A$. In earthworms,the alimentary canal sequence is mouth,buccal cavity,pharynx,oesophagus,gizzard,stomach,and intestine. The gizzard is located after the oesophagus,but the sequence provided is incomplete/incorrect regarding the standard anatomical order.
$B$. The body of a frog is divided into head and trunk only; it does not have a neck.
$C$. In mammals like rats (and humans),the left kidney is typically situated slightly higher than the right kidney due to the position of the liver on the right side.
$D$. Cockroaches have $10$ pairs of spiracles,but they are arranged as $2$ pairs in the thorax and $8$ pairs in the abdomen. This statement is factually correct.

(A) Periplaneta (cockroach) belongs to the phylum Arthropoda.
Arthropods are characterized by the presence of jointed appendages,which serve as their primary locomotory organs.
These appendages are modified for various functions including walking,running,and climbing.
Setae are found in Annelids,muscular feet in Molluscs,and tube feet in Echinoderms.

(A) The exoskeleton of a cockroach $(Periplaneta \text{ } americana)$ is composed of hard, chitinous plates known as sclerites. Chitin is a nitrogen-containing polysaccharide that provides structural support and protection to the insect's body.

(C) The process of shedding the exoskeleton in insects,such as the cockroach,during their growth and development is known as $Ecdysis$ or molting.
This occurs because the rigid exoskeleton does not grow with the body,so the insect must shed it to accommodate its increasing size.
$Metamorphosis$ refers to the biological process by which an animal physically develops after birth or hatching.
$Polymorphism$ is the occurrence of two or more clearly different morphs or forms in the population of a species.
$Parthenogenesis$ is a form of asexual reproduction in which an embryo develops from an unfertilized egg.

(B) The scientific name of the common cockroach is $Periplaneta$ $americana$.
Therefore,the genus of the cockroach is $Periplaneta$.
$Rana$ is the genus of frogs.
$Pheretima$ is the genus of earthworms.
$Zea$ is the genus of maize (corn).

(B) The scientific classification of the American cockroach $(Periplaneta \ americana)$ is as follows:
$1$. Phylum: Arthropoda (jointed appendages).
$2$. Class: Insecta (three pairs of legs,body divided into head,thorax,and abdomen).
$3$. Order: Blattodea (cockroaches).
$4$. Family: Blattidae.
$5$. Genus: $Periplaneta$.
$6$. Species: $americana$.
Therefore,option $B$ provides the correct taxonomic hierarchy.

(B) The taxonomic classification of the American cockroach $(Periplaneta \ americana)$ is as follows:
$1$. Phylum: Arthropoda (Jointed appendages)
$2$. Class: Insecta (Three pairs of legs)
$3$. Order: Blattodea (Cockroaches)
$4$. Family: Blattidae
$5$. Genus: Periplaneta
$6$. Species: americana
Therefore, the correct sequence is $Arthropoda \rightarrow Insecta \rightarrow Blattodea \rightarrow Blattidae \rightarrow Periplaneta \rightarrow americana$.

(D) $Periplaneta$ $americana$ (cockroach) belongs to the phylum $Arthropoda$.
In insects,the cleavage during embryonic development is superficial,not radial or indeterminate.
Radial and indeterminate cleavage are characteristic features of deuterostomes (e.g.,echinoderms and chordates).
Therefore,option $D$ is the correct answer as it is not a feature of $Periplaneta$ $americana$.

(A) The correct answer is $A$.
In the body of a cockroach,the exoskeleton consists of hardened plates called sclerites.
The dorsal plates are called terga,the ventral plates are called sterna,and the lateral plates are called pleura.
These sclerites are joined to each other by a thin,flexible,and tough cuticle known as the arthrodial membrane,which allows for movement between the segments.

(A) The cockroach undergoes paurometabolous development,meaning the nymphal stages resemble the adult. The nymph moults about $13$ times to reach the adult form. The next-to-last nymphal stage has wing pads,but only the adult cockroach possesses fully developed wings (forewings and hindwings). Therefore,the development of wings is the primary external change visible after the final moult.

(B) : Malpighian tubules are the main excretory organs in cockroaches. They extract nitrogenous wastes and water from the haemolymph and reabsorb certain salts,resulting in the excretion of uric acid. Thus,cockroaches are uricotelic. Males possess a pair of anal styles on the $9^{th}$ abdominal sternite,which are absent in females.

(B) is the correct statement.
In $Periplaneta$ $americana$ (cockroach),the posterior segment of the abdomen bears a pair of jointed filamentous structures called anal cerci,which are present in both sexes.
However,males can be distinguished from females by the presence of an additional pair of short,thread-like structures called anal styles.
These anal styles assist in the process of copulation.

(B) The head of a cockroach is triangular in shape and lies anteriorly at right angles to the longitudinal body axis.
It is formed by the fusion of $6$ embryonic segments.
These segments are highly modified to form the head capsule,which bears the mouthparts,antennae,and compound eyes.

(B) In male cockroaches,the abdomen consists of $10$ segments.
The male genital pore is situated ventrally,specifically in the mid-ventral region of the $9^{th}$ segment.
This pore is surrounded by genital structures such as gonapophyses or phallomeres.
Therefore,the correct option is $B$.

(B) In cockroaches,the sense organs include antennae,eyes (compound eyes),maxillary palps,labial palps,and anal cerci.
Antennae are sensory organs that help in monitoring the environment.
Eyes are visual organs.
Anal cerci are paired appendages on the $10^{th}$ abdominal segment that act as sensory organs sensitive to vibrations in the ground and air.
Wings are locomotory organs used for flight,not sensory organs.

(B) The scientific name of the common American cockroach is $Periplaneta$ $americana$.
$Rana$ $tigrina$ is the scientific name of the Indian bullfrog.
$Pheretima$ $posthuma$ is the scientific name of the earthworm.
$Eichhornia$ $crassipes$ is the scientific name of the water hyacinth.

(B) The arthrodial membrane is a thin, flexible, and soft chitinous membrane.
It connects the sclerites (hardened plates of the exoskeleton) in insects, specifically in the cockroach $(Periplaneta \text{ } americana)$.
This membrane allows for the movement of the body segments and appendages by providing flexibility between the rigid plates of the exoskeleton.
Therefore, the correct answer is $B$ (Cockroach).

(A) The cockroach $(Periplaneta \text{ } americana)$ possesses an open type of circulatory system, not a closed one. In an open circulatory system, the blood (hemolymph) flows into body cavities called sinuses. Therefore, the statement 'Blood vascular system - closed' is incorrect. The other options are correct: the respiratory system consists of a network of trachea, the head is triangular in shape, and the eyes are compound.

(B) The abdomen of both male and female cockroaches consists of $10$ segments.
In female cockroaches,the $7$th sternum is boat-shaped and together with the $8$th and $9$th sterna,forms a brood or genital pouch.
In males,the genital pouch is present at the hind end of the abdomen bounded dorsally by the $9$th and $10$th terga and ventrally by the $9$th sternum.

(D) In male cockroaches,the $9^{th}$ abdominal segment bears a pair of short,thread-like anal styles,which are absent in females.
Anal cerci are a pair of jointed filamentous structures present in both male and female cockroaches on the $10^{th}$ segment.
Phallomeres are chitinous asymmetrical structures surrounding the male gonopore,which are specific to male cockroaches.
Since all three structures (anal cerci,phallomeres,and anal styles) are found in male cockroaches,the correct answer is $D$.

(A) In cockroaches,the $9^{th}$ abdominal segment in males bears a pair of short,thread-like anal styles,which are absent in females.
Anal cerci are present in both sexes.
Tarsus is a part of the leg and is present in both sexes.
Mouth parts are present in both sexes for feeding.

(A) In cockroaches,the antennae are sensory organs located on the head. They contain various sensory receptors that allow the organism to monitor the surrounding environment,such as detecting vibrations,chemicals,and changes in air currents. Therefore,both the assertion $(A)$ and the reason $(R)$ are correct,and the reason correctly explains the function of the antennae.

(A) The development of the cockroach is paurometabolous, meaning development occurs through the nymphal stage.
The nymph looks very much like the adult.
The nymph grows by moulting (ecdysis) about $13$ times to reach the adult form.
The next nymphal stage is very similar to the adult, except for the lack of wings and external genitalia.

(C) The process of ootheca formation in a cockroach follows these steps:
$1$. First,the ova enter the genital chamber.
$2$. Second,the ova are fertilized by sperms within the genital chamber.
$3$. Third,a protective cover (ootheca) is secreted around the fertilized eggs.
Therefore,the correct sequence is $1 \rightarrow 3 \rightarrow 2$.

(A) The figure represents the circulatory system of a cockroach.
In cockroaches,the heart consists of an elongated tube with $13$ funnel-shaped chambers.
The label $X$ points to these specific chambers of the heart.
Therefore,the correct option is $A$.

(B) In cockroaches,the female produces a dark reddish to blackish brown capsule called an $ootheca$.
This $ootheca$ contains the fertilised eggs.
Each $ootheca$ is dropped or glued to a suitable surface,usually in a crack or crevice of high relative humidity near a food source.
Therefore,the $ootheca$ covers the fertilised eggs in the female.

(A) In cockroaches,sexual dimorphism is present.
Male cockroaches can be distinguished from females by the presence of a pair of short,thread-like anal styles on the $9^{th}$ sternum.
Anal cerci are present in both males and females on the $10^{th}$ segment.
Therefore,the presence of anal styles in males is the primary external feature used to distinguish them from females.

(C) Statement $-A$ is true because $Periplaneta$ $americana$ (cockroach) is indeed a nocturnal,omnivorous,and household pest that causes damage to food and contaminates it.
Reason $-R$ is also true because cockroaches are scavengers,meaning they feed on decaying organic matter,waste,and food scraps.
Since the cockroach's habit of being a scavenger is the primary reason it thrives as a household pest (by feeding on human waste and food),$R$ is the correct explanation of $A$.

(B) $1$. The nervous system of the cockroach consists of a series of fused,segmentally arranged ganglia joined by paired longitudinal connectives on the ventral side. Thus,option $A$ is incorrect.
$2$. Males possess a pair of short,thread-like anal styles,which are absent in females. Thus,option $B$ is correct.
$3$. $100-150$ yellow-colored thin filamentous Malpighian tubules are present at the junction of the midgut and hindgut,not $16$. Thus,option $C$ is incorrect.
$4$. The grinding of food is performed by the gizzard (proventriculus),not the mouthparts. Thus,option $D$ is incorrect.

(D) The development of a cockroach is paurometabolous,meaning it undergoes gradual metamorphosis through nymphal stages. The nymph looks very much like an adult. The nymph grows by moulting (ecdysis) about $13$ times to reach the adult form. The next to last nymphal stage has wing pads,but only the adult cockroaches have fully developed wings (forewings and hindwings).

(A) The cockroach $(Periplaneta \text{ } americana)$ belongs to the phylum $Arthropoda$.
Key characteristics of arthropods include a chitinous exoskeleton made of $N$-acetylglucosamine, a metamerically segmented body, and a haemocoel (blood-filled body cavity).
However, indeterminate and radial cleavage are characteristic features of deuterostomes (like echinoderms and chordates).
Cockroaches, being protostomes, exhibit determinate and spiral cleavage during embryonic development.
Therefore, the correct answer is $A$.

(D) In insects like the cockroach,the circulatory system is of the open type. The blood (hemolymph) does not contain respiratory pigments like hemoglobin and lacks $RBC$ (erythrocytes). Instead,oxygen is transported directly to tissues via the tracheal system. In contrast,frogs,cows,and camels are vertebrates and possess $RBC$ in their blood.

(D) In male cockroaches,the $9th$ abdominal segment bears a pair of short,thread-like anal styles (caudal styles).
These structures are absent in female cockroaches.
Anal cerci are present in both male and female cockroaches.
The $7th$ sternum is boat-shaped in females,not males.
Therefore,the presence of caudal styles is the diagnostic feature used to distinguish a male cockroach from a female.

(B) Cockroaches belong to the class $Insecta$ and the phylum $Arthropoda$.
$Arthropoda$ is the largest phylum of $Animalia$ which includes insects.
Cockroaches are characterized by a chitinous exoskeleton,jointed appendages,and a segmented body,which are key features of the phylum $Arthropoda$.

(C) The dissecting microscope allows for the viewing of $3D$ images at magnifications up to $50x$. It is commonly used during dissections to observe external morphological features.
An ultracentrifuge is used to separate components of a mixture based on density by spinning at high speeds.
Microdissection instruments are specialized tools used for manipulating microscopic structures,such as cell nuclei.
Electron microscopes provide extremely high magnification (up to $250,000x$) and are used to study internal cellular ultrastructure,not external features of an organism.

(B) Based on the anatomy of the cockroach head:
$A$ represents the Ocellus (fenestra),which is a simple eye.
$B$ represents the Compound eye.
$C$ represents the Mandible,which is a hard,biting jaw.
$D$ represents the Maxilla,which helps in food manipulation.
$E$ represents the Labrum,which acts as the upper lip.
$F$ represents the Labium,which acts as the lower lip.
Therefore,the correct sequence is $A-$ Ocellus,$B-$ Compound eye,$C-$ Mandible,$D-$ Maxilla,$E-$ Labrum,$F-$ Labium.

(D) Both sexes of the cockroach possess anal cerci,which are jointed,paired structures located on the $10^{th}$ abdominal segment.
However,the male cockroach possesses an additional pair of unjointed,needle-like structures called anal styles on the $9^{th}$ abdominal segment.
These anal styles are absent in the female cockroach,making them a key morphological feature for distinguishing between the two sexes.

(N/A) The common name of $Periplaneta \text{ } americana$ is the American cockroach.

(10) In both male and female cockroaches,the abdomen consists of $10$ segments.

(D) The mouthparts of a cockroach consist of a labrum (upper lip),a pair of mandibles,a pair of maxillae,and a labium (lower lip).
Maxilla,mandible,and labrum are all components of the mouthparts of a cockroach.
Antennae are sensory organs located on the head of the cockroach,not part of the mouthparts.
Therefore,antennae is the odd one out.

(N/A) $\rightarrow$ Cockroaches are brown or black-bodied animals.
$\rightarrow$ Cockroaches are included in the class $Insecta$ of the phylum $Arthropoda$. Bright yellow,red,and green-coloured cockroaches have also been reported in tropical regions.
$\rightarrow$ Their size ranges from $1/4$ inches to $3$ inches. They possess antennae,legs,and a flat extension of the upper body wall that conceals the head.
$\rightarrow$ They are nocturnal omnivores that live in damp places throughout the world.
$\rightarrow$ They have become residents of human homes and thus are serious pests and vectors of several diseases.

(N/A) $\rightarrow$ The adults of the common species of cockroach are $Periplaneta$ $americana$.
$\rightarrow$ The body of the cockroach is long,dorso-ventrally flattened,and brownish-red in colour.
$\rightarrow$ Adult cockroaches have a length of $25 \ mm$ to $45 \ mm$ and a breadth of $8 \ mm$ to $12 \ mm$.
$\rightarrow$ The body is covered by a hard,chitinous exoskeleton.
$\rightarrow$ In each segment,the exoskeleton has hardened plates called tergites (dorsally) and sternites (ventrally),which are joined to each other by a thin and flexible articular membrane called the arthrodial membrane.
$\rightarrow$ The body is segmented and divisible into three distinct regions: head,thorax,and abdomen.
$\rightarrow$ Head: The head is triangular in shape and lies anteriorly at right angles to the longitudinal body axis. It is formed by the fusion of six segments and bears a pair of compound eyes and a pair of thread-like antennae.
$\rightarrow$ Mouth parts: The mouth parts consist of a labrum (upper lip),a pair of mandibles,a pair of maxillae,and a labium (lower lip). $A$ median flexible lobe acting as a tongue (hypopharynx) lies within the cavity enclosed by the mouth parts.
$\rightarrow$ Thorax: The thorax consists of three parts: prothorax,mesothorax,and metathorax. Each thoracic segment bears a pair of walking legs. The first pair of wings arises from the mesothorax (tegmina) and the second pair from the metathorax.
$\rightarrow$ Abdomen: The abdomen in both males and females consists of $10$ segments. In females,the $7^{th}$ sternum is boat-shaped and forms a brood or genital pouch. In males,the genital pouch lies at the hind end of the abdomen,bounded dorsally by the $9^{th}$ and $10^{th}$ terga and ventrally by the $9^{th}$ sternum. Anal cerci are present in both sexes,while anal styles are present only in males.

(N/A) $\rightarrow$ Many species of cockroaches are wild and are of no economic importance.
$A$ few species thrive in and around human habitats.
They are considered pests because they destroy food and contaminate it with their smelly excreta.
They act as vectors and can transmit a variety of bacterial diseases by contaminating food material and water.

(N/A) $\rightarrow$ The head of a cockroach is triangular in shape and lies anteriorly at right angles to the longitudinal body axis.
$\rightarrow$ It is connected to the thorax by a short,thin,and flexible neck.
$\rightarrow$ The head is formed by the fusion of six embryonic segments.
$\rightarrow$ The head capsule bears a pair of large,sessile,compound eyes. These are bean-shaped.
$\rightarrow$ $A$ pair of thread-like antennae arise from membranous sockets lying in front of the eyes. These antennae contain sensory receptors that help in monitoring the environment.
$\rightarrow$ The anterior end of the head bears appendages that form biting and chewing type of mouthparts,which include the labrum,a pair of mandibles,a pair of maxillae,and the labium.