Morphology of Frog Questions in English

(D) The absence of a neck in a frog is an evolutionary adaptation that provides a streamlined body shape. This structural feature reduces air resistance and provides stability during the powerful leaps required for jumping on the ground. Therefore,the correct option is $D$.

(B) The forelimbs of a frog are shorter and consist of four digits (fingers).
The hindlimbs are longer and consist of five digits (toes),which are webbed to help in swimming.
Therefore,a frog has four fingers on its forelimbs and five toes on its hindlimbs.

(A) The skin of a frog is moist,smooth,and slippery due to the presence of mucous glands.
Additionally,the skin contains poisonous glands that secrete toxins to protect the frog from predators.
Therefore,the correct answer is $A$.

(A) The zoological name of the common Indian bullfrog is $Rana \text{ } tigrina$.
It belongs to the class $Amphibia$ and the order $Anura$.
Therefore, the correct option is $A$.

(D) The correct answer is $(d)$. Frogs are amphibians,meaning they are capable of living both in water and on land.
They are typically found in or near freshwater bodies such as ponds,lakes,ditches,marshes,and slow-moving streams.
Their dual habitat allows them to utilize both environments for different life stages and activities.

(D) The Indian bullfrog,scientifically known as $Hoplobatrachus \ tigerinus$,is an amphibian.
It is commonly found in freshwater habitats such as ponds,streams,and shallow lakes.
These environments provide the necessary moisture and aquatic conditions required for their survival and reproduction.
Therefore,all the given options are correct habitats for the Indian bullfrog.

(C) Toads belong to the family $Bufonidae$.
Unlike frogs,which typically have smooth,moist skin,toads are characterized by having dry,warty skin.
They possess prominent parotid glands behind their eyes,which secrete toxins as a defense mechanism.
Additionally,they generally have a more rounded or semicircular snout compared to the pointed snout of many frogs.
Therefore,option $C$ is the correct description.

(A) The elevated poison-secreting glands,known as parotid glands,are present behind each tympanum in the genus $Bufo$.

(B) Frogs are cold-blooded animals (poikilotherms) that cannot regulate their internal body temperature.
To survive extreme environmental conditions,they undergo periods of dormancy.
$1$. Aestivation is the state of dormancy or 'summer sleep' that frogs enter during hot and dry summer months to prevent desiccation.
$2$. Hibernation is the state of 'winter sleep' that they enter during cold winter months to conserve energy.
Therefore,the summer sleep of a frog is termed as Aestivation.

(D) The frog $(Rana \, tigrina)$ is widely used in educational institutions for the following reasons:
$1$. They are easily available in nature and are inexpensive to procure.
$2$. Their body size is appropriate for performing dissections to study internal organ systems.
$3$. They are non-poisonous, making them safe for students to handle during laboratory sessions.
Therefore, all the given options are correct.

(A) In frogs,the male possesses a pair of vocal sacs that act as resonators to amplify sound,allowing them to produce a loud croaking call to attract females during the breeding season.
Female frogs lack these vocal sacs and therefore do not produce the characteristic croaking sound associated with males.

(D) The croaking sound produced by male frogs is a mating call or a sex call.
This sound is produced to attract females for the purpose of reproduction.
Male frogs have vocal sacs that amplify this sound,making it audible over long distances.

(A) The body of a frog is divisible into two main parts: the head and the trunk.
Unlike many other vertebrates,frogs do not possess a distinct neck or a tail in their adult stage.
Therefore,the correct division is head and trunk.

(D) The absence of a neck in a frog is an evolutionary adaptation that provides a streamlined body shape.
This streamlined shape reduces resistance while moving through the water,thereby facilitating efficient swimming.
Therefore,the correct option is $D$.

(C) Frogs,particularly tree frogs,have the ability to climb surfaces due to the presence of specialized adhesive pads (also known as toe pads) on their fingers and toes.
These pads contain numerous mucous glands that secrete a sticky substance,which,combined with the microscopic structure of the pads,allows them to adhere to smooth surfaces like leaves or tree bark.

(B) The skin of a frog is smooth and slippery due to the presence of mucus. The mucous glands present in the skin secrete a slimy fluid called mucus,which keeps the skin moist. This moisture is essential for cutaneous respiration,as frogs breathe through their skin in water and on land.

(A) The skin of a frog is smooth and slippery due to the presence of mucous glands.
It is composed of two main layers: the epidermis and the dermis.
Mucous glands and poison glands are present in the dermis and open onto the surface of the skin.
Scales are characteristic of reptiles and are absent in the skin of amphibians like frogs.

(A) The adult frog is carnivorous. It is a predator that feeds on insects,spiders,worms,and other small invertebrates.

(D) Frogs are carnivorous animals that primarily feed on living,moving prey such as insects,worms,molluscs,and tadpoles.
Their visual system is highly sensitive to movement,which triggers their feeding response.
Consequently,any motionless object or dead food is typically ignored by the frog.

(C) Frogs rely heavily on visual stimuli to initiate movement and respond to their environment. When a frog's eyes are covered,it loses the ability to perceive its surroundings,which leads to a state of inactivity or lack of response to external stimuli. Therefore,the frog will not do anything.

(D) The croaking sound produced by male frogs is a vocalization used to attract female partners for mating. This behavior is a form of sexual selection,where the intensity and frequency of the call help females identify suitable mates.

(B) The brow spot (also known as the frontal organ or parietal spot) in frogs is a vestigial structure located on the dorsal surface of the head. It represents the remnant of the median or pineal eye,which was present in ancestral vertebrates. Therefore,it is considered a vestige of a median eye.

(A) Calcified cartilage is a type of cartilage where the matrix becomes impregnated with calcium salts,making it hard and rigid.
In frogs,the femur (thigh bone) contains calcified cartilage,which provides structural support.
This is a characteristic feature of the skeletal system in amphibians like frogs.

(A) In mammals,including rabbits,mature $RBCs$ (red blood cells) are enucleated (lack a nucleus) to provide more space for hemoglobin,which increases the oxygen-carrying capacity of the blood.
In contrast,amphibians like frogs possess nucleated $RBCs$ even in their mature state.
Therefore,the correct answer is frog.

(A) The common Indian bullfrog belongs to the species $Rana$ $tigrina$.
$Rana$ $esculenta$ is the edible frog found in Europe.
$Rana$ $silvatica$ is the wood frog.
$Rana$ $goliath$ is the largest frog in the world.

(A) The skin of the frog is smooth and slippery due to the presence of mucus. The skin is always maintained in a moist condition. The color of the dorsal side of the body is generally olive green with dark spots. On the other hand,the ventral side of the body is uniformly pale yellow in color.

(A) $Rana \, tigrina$ is the scientific name of the common Indian bullfrog. It belongs to the class $Amphibia$ and the order $Anura$. Therefore, the correct option is $A$.

(B) The head of a frog is $triangular$ in shape. The anterior conical part of the head is known as the $snout$.

(C) The absence of a neck in frogs is an adaptation that helps in streamlining the body. This streamlined shape reduces resistance while swimming in water,allowing the frog to move efficiently through the aquatic environment. Therefore,the correct answer is $C$.

(C) $1$. Frogs are poikilothermic (cold-blooded) animals, meaning they cannot regulate their body temperature internally. Thus, option $A$ is incorrect.
$2$. Frogs do not drink water; they absorb it through their skin. Thus, option $B$ is incorrect.
$3$. Many species of frogs, especially those in the family $Dendrobatidae$, possess poison glands in their skin to protect themselves from predators. However, in the context of the common frog $(Rana \, tigrina)$ studied in $NCERT$, the skin is moist and slimy due to mucus glands, but the statement 'poison glands are not found' is generally considered a characteristic feature of the common frog compared to toxic species. Thus, option $C$ is the most appropriate statement.
$4$. Adult frogs do not have a tail. Thus, option $D$ is incorrect.

(A) The forelimbs and hindlimbs of a frog help in swimming,walking,leaping,and burrowing. The forelimbs are shorter than the hindlimbs. Each forelimb of a frog consists of a humerus,radio-ulna,carpals,metacarpals,and phalanges. Specifically,the forelimb of a frog has $4$ digits,whereas the hindlimb has $5$ digits.

(A) In frogs,the ear is an organ of hearing as well as balancing. The ear consists of only the middle ear and the internal ear. The external ear is absent in frogs. Instead,a membranous structure called the tympanum is present on the surface of the head,which receives sound vibrations.

(C) The genus of the common frog is $Rana$.
$Periplaneta$ is the genus of the cockroach.
$Pheretima$ is the genus of the earthworm.
$Helianthus$ is the genus of the sunflower.

(B) In the anatomy of a mature frog $(Rana \, tigrina)$, the body is divided into head and trunk. Unlike many other vertebrates, frogs lack a neck, which prevents them from turning their heads independently. Additionally, while the tadpole larva possesses a tail for swimming, the tail is completely reabsorbed during the process of metamorphosis into an adult frog. Therefore, both the neck and the tail are absent in a mature frog.

(C) Frogs do not have an external ear (pinna). Instead,they possess a tympanum,which is a membranous structure that receives sound vibrations. The internal ear is present,as are the alimentary canal and nostrils,which are essential for digestion and respiration,respectively.

(B) Frogs are amphibians and do not possess an exoskeleton (like scales,feathers,or hair) on their skin. Their skin is moist and glandular. Digits are present on their limbs. The pancreas is a digestive gland present in both sexes. The ureter is part of the excretory system,present in both male and female frogs.

(B) The $Nuptial$ $pad$ (also known as the $copulatory$ $pad$) is a specialized structure found on the ventral side of the first digit of the forelimbs in male frogs.
It helps the male to grasp the female during the process of amplexus (mating).
Tympanic membrane,rectum,and cloaca are present in both male and female frogs.

(C) The skin of a frog serves multiple vital functions:
$1$. It acts as a sensory organ by detecting environmental stimuli.
$2$. It provides protection against mechanical injury and pathogens.
$3$. It serves as a respiratory organ,allowing for cutaneous respiration,which is essential for gas exchange.
$4$. Digestion is a function of the alimentary canal,not the skin. Therefore,digestion is not a function of the skin of a frog.

(A) In frogs,the male possesses vocal sacs which act as resonators to amplify their croaking sound to attract females during the breeding season.
Female frogs lack these vocal sacs.
Cloaca is present in both sexes as a common chamber for the digestive,urinary,and reproductive tracts.
Oviduct is a female reproductive organ,so it is present in females.
Glottis is the opening to the respiratory tract,present in both sexes.

(A) The scientific name of the Indian bullfrog is $Rana \ tigrina$.
It is a species of frog found in India and other parts of South Asia.
$Rana \ catesbeiana$ is the American bullfrog,while $Rana \ sylvatica$ is the wood frog.

(D) Frogs possess various types of sense organs to interact with their environment.
These include sensory papillae for the sense of touch,taste buds for taste,nasal epithelium for smell,eyes for vision,and the tympanum with internal ears for hearing.
Therefore,sensory papillae are specifically associated with the sense of touch.

(N/A) $\rightarrow$ Frogs can live both on land and in fresh water and belong to the class $Amphibia$ of the phylum $Chordata$. The most common species of frog found in India is $Rana$ $tigrina$.
$\rightarrow$ They do not have a constant body temperature,i.e.,their body temperature varies with the temperature of the environment. Such animals are called cold-blooded or poikilotherms.
$\rightarrow$ The colour of the frog changes while they are in grasses and on dry land. They have the ability to change their colour to hide from their enemies. This protective coloration is known as camouflage or mimicry.
$\rightarrow$ Frogs take shelter in deep burrows to protect themselves from extreme heat and cold during summer and winter. This is known as summer sleep $(aestivation)$ and winter sleep $(hibernation)$.

(N/A) $\rightarrow$ Skin of frog: The skin of a frog is smooth and slippery due to the presence of mucus. The skin lacks an exoskeleton and is always maintained in a moist condition.
$\rightarrow$ The colour of the dorsal side of the body is generally olive green with dark irregular spots. On the ventral side, the skin is uniformly pale yellow.
$\rightarrow$ A frog does not drink water but absorbs it through the skin.
$\rightarrow$ The body of a frog is divisible into head and trunk. A neck and tail are absent.
$\rightarrow$ Above the mouth, a pair of nostrils is present.
$\rightarrow$ Eyes are bulged and covered by a nictitating membrane that protects them while in water.
$\rightarrow$ On either side of the eyes, a membranous tympanum (ear) receives sound signals.
$\rightarrow$ The forelimbs and hind limbs help in swimming, walking, leaping, and burrowing.
$\rightarrow$ Feet have webbed digits that help in swimming.
$\rightarrow$ Sexual dimorphism in frogs: Frogs exhibit sexual dimorphism. Male frogs can be distinguished by the presence of sound-producing vocal sacs and a copulatory pad on the first digit of the forelimbs, which are absent in female frogs.
$\rightarrow$ During the mating period, the skin colour of the male frog becomes dark yellow. No such colour change occurs in females.
$\rightarrow$ In male frogs, the abdomen region is narrow and flat, while during the reproductive season, the abdomen of the female becomes broad and inflated due to the development of numerous egg cells in the ovary.

(N/A) $\rightarrow$ Frogs are beneficial to mankind because they consume insects and protect crops from pests.
$\rightarrow$ Frogs maintain ecological balance by serving as an important link in the food chain and food web within the ecosystem.
$\rightarrow$ In some countries,the muscular legs of the frog are consumed as food by humans.

(N/A) The differences between a male frog and a female frog are as follows:
$1$. Vocal sacs: Male frogs possess a pair of vocal sacs,which are absent in female frogs.
$2$. Copulatory pad: Male frogs have a copulatory pad (nuptial pad) on the first digit of each forelimb,which is absent in female frogs.
$3$. Size: Generally,male frogs are smaller in size compared to female frogs.
$4$. Sound: Male frogs can produce a croaking sound using their vocal sacs to attract females during the breeding season,whereas females do not produce such sounds.

(N/A) Frogs are considered beneficial for human life due to the following reasons:
$1$. Ecological Balance: Frogs act as important predators in the ecosystem. They feed on insects and pests that damage crops,thereby acting as natural biological control agents.
$2$. Food Chain: They serve as an essential link in the food chain by being both predators (of insects) and prey (for snakes,birds,and other animals),helping to maintain the stability of the ecosystem.
$3$. Scientific Research: Frogs are widely used in biological and medical research,particularly in developmental biology and physiology,due to their relatively simple anatomy and accessible embryos.
$4$. Environmental Indicators: As amphibians,they are highly sensitive to environmental changes and pollution. Their presence or absence serves as an indicator of the health of an ecosystem.

(N/A)

Male Frog	Female Frog
$(1)$ It has two vocal sacs.	$(1)$ It has no vocal sacs.
$(2)$ It has a copulatory pad on the first digit of the forelimb.	$(2)$ It is absent in females.
$(3)$ It obtains a dark yellow colour of skin during the reproductive period.	$(3)$ No change in skin colour is observed.
$(4)$ Its abdominal region is narrow and flat.	$(4)$ During the reproductive period,the abdomen becomes broad and swollen.

(N/A) Frogs are considered beneficial to mankind for the following reasons:
$1$. They are an important link in the food chain and ecosystem. They act as predators of insects and pests,thereby controlling their population.
$2$. They protect crops from damage by feeding on harmful insects.
$3$. Frogs are widely used in biological and medical research as laboratory animals for dissection and physiological studies.
$4$. In some cultures,frog legs are consumed as a source of protein.

(N/A) $\Rightarrow$ Frogs are beneficial for mankind because they feed on insects and act as natural pest controllers,thereby protecting crops.
$\Rightarrow$ Frogs maintain ecological balance as they serve as an important link in the food chain and food web within the ecosystem.
$\Rightarrow$ In some countries,the muscular legs of the frog are consumed as food by humans.