BZYCT131 solved Free Assignment 2023
BZYCT131 Solved Free Assignment January 2023
a) What is the difference between dinoflagellates and apicomplexans?
Ans. a) Dinoflagellates and apicomplexans are both types of protists, but they belong to different phyla and have distinct characteristics.
Dinoflagellates: Dinoflagellates are a group of unicellular, photosynthetic protists that are characterized by two flagella, one of which is located in a groove that encircles the cell.
They are known for their diverse shapes and ecological importance, as they are important components of marine and freshwater ecosystems.
Dinoflagellates are primarily marine, but some species can also be found in freshwater habitats. BZYCT131 Solved Free Assignment 2023
They can be autotrophic (photosynthetic) or heterotrophic (non-photosynthetic), and some species are bioluminescent, producing light when disturbed.
Apicomplexans: Apicomplexans are a group of parasitic protists that are characterized by the presence of a complex structure called the apical complex, which is used for host cell invasion.
They are mostly parasitic and can cause diseases in humans and other animals, such as malaria (caused by Plasmodium spp.) and toxoplasmosis (caused by Toxoplasma gondii).
Apicomplexans do not have flagella and are usually non-motile, relying on host cells for their survival and reproduction.
b) List three unique features of Phylum Ciliophora.
Ans b) Three unique features of Phylum Ciliophora, which are characteristics of ciliates, are: BZYCT131 Solved Free Assignment 2023
Cilia: Ciliates are named after the presence of numerous hair-like structures called cilia, which cover their body surface and are used for locomotion, feeding, and sensory functions.
Cilia are short and numerous, arranged in specific patterns, and can be used for diverse functions, such as creating water currents, capturing food particles, and sensing the environment.
Macronucleus and Micronucleus: Ciliates have two types of nuclei – a macronucleus and a micronucleus.
The macronucleus controls the everyday functions of the cell, such as metabolism and reproduction, while the micronucleus is involved in sexual reproduction and genetic exchange. BZYCT131 Solved Free Assignment 2023
Oral Groove and Cytostome: Ciliates have a specialized feeding structure called the oral groove, which is a ciliated groove on the cell surface that leads to a cytostome or mouth.
The cytostome is a specialized feeding organelle that allows ciliates to ingest food particles, such as bacteria and algae.
c) Which of the following is not true for animals with radial symmetry?
i) Non front and back ends
ii) Are always sessile
iii) No left or right sides
iv) Face the environment from all sides
Ans. c) ii) Are always sessile. This statement is not true for animals with radial symmetry. Radially symmetrical animals can be either sessile or motile.
Radial symmetry means that the body is arranged in a circular or radial pattern, and the body parts are arranged around a central axis, like the spokes of a wheel.
Examples of animals with radial symmetry include jellyfish, sea anemones, and starfish. BZYCT131 Solved Free Assignment 2023
While some radially symmetrical animals, such as sea anemones, may be sessile and attached to a substrate, others, such as jellyfish, are motile and can move through water.
d) Match the following:
Ans. i) frontal plane – a) Divides body into left and right
ii) sagittal plane – d) Divides body into dorsal and ventral parts
iii) bilateral symmetry – b) Only one imaginary line divides the body into mirror images
iv) asymmetrical – c) Cannot be divided into mirror images
Q 2. Complete the following sentences inserting appropriate words in blanks:
i) Porifera are ………………. cellular animals incapable of
……………… as they remain to the substratum like a
ii) The sponge body is covered by an outer epithelial layer made up of
iii) Sponges with skeleton made up of spicules of calcium carbonate
belong to the class …………………. .
Ans. i) Porifera are multicellular animals incapable of locomotion as they remain attached to the substratum like a sessile organism.
ii) The sponge body is covered by an outer epithelial layer made up of cells called pinacocytes. BZYCT131 Solved Free Assignment 2023
iii) Sponges with a skeleton made up of spicules of calcium carbonate belong to the class Calcarea.
b) Write true (T) or false (F) in the space provided against each statement.
i) Cnidocyte has a hair like cnidocil which acts as a trigger.
ii) Medusae are asexual zooids.
iii) Obelia colony is bimorphic.
iv) Obelia is a fresh water plant like animal found attached to
v) Gonangium is a sexual way of reproduction.
Ans. i) T (True)
ii) F (False)
iii) T (True)
iv) F (False)
v) F (False)
- Please attempt the following questions:
i) Which of the words given in the parantesis is correct? Flame cells in platyhelmninthes are ……………….. in function.
Ans. Flame cells in platyhelminthes are excretory in function.
ii) Arrange the character most appropriate to the class of Platyhelminthes against it.
a) Turbellaria i) Presence of scolex
b) Monogenea ii) Presence of oral and ventral suckers, but no hooks
c) Trematoda iii) Presence of posterior hooks, suckers, clamps etc.
d) Cestoda iv) Ciliated epidermal cells covering the body.
Ans. Classes Characters
a) Turbellaria iv) Ciliated epidermal cells covering the body.
b) Monogenea ii) Presence of oral and ventral suckers, but no hooks.
c) Trematoda iii) Presence of posterior hooks, suckers, clamps etc.
d) Cestoda i) Presence of scolex. BZYCT131 Solved Free Assignment 2023
iii) What do you mean by true coelomates? Discuss their advantages
Ans. True coelomates, also known as eucoelomates, are animals that possess a true coelom, which is a body cavity lined by mesoderm on both sides.
The coelom is a fluid-filled cavity that lies between the body wall and the gut wall.
True coelomates represent a significant advancement in body plan organization compared to animals without a coelom or those with a pseudocoelom, which is a body cavity only partially lined by mesoderm.
Advantages of True Coelomates: BZYCT131 Solved Free Assignment 2023
Improved Organ Development and Function: The presence of a true coelom provides ample space for the organs to develop and function efficiently.
It allows for the proper positioning and suspension of organs within the body cavity, which helps prevent damage from external mechanical forces and allows for their proper functioning.
Organs can also move independently within the coelom, which allows for greater flexibility and efficiency in performing their respective functions.
Enhanced Muscular Function: The coelom acts as a hydrostatic skeleton, providing support to the body and allowing for more precise and coordinated movements of the muscles. BZYCT131 Solved Free Assignment 2023
Muscles can attach to the body wall and exert force against the fluid in the coelom, resulting in more effective and efficient movements.
This is particularly advantageous for animals that require rapid and coordinated movements for locomotion, such as complex body plans like those of arthropods and vertebrates.
Improved Circulation and Respiration: The coelom allows for the circulation of body fluids, such as blood and lymph, within the cavity.
This facilitates the transport of nutrients, gases, and waste products, allowing for efficient respiration and circulation throughout the body.
In some true coelomates, the coelomic fluid may even play a role in gas exchange, aiding in respiration. BZYCT131 Solved Free Assignment 2023
Greater Protection and Adaptability: The coelom acts as a protective barrier, isolating the organs from the external environment and preventing direct contact with the body wall.
This provides an added layer of protection against mechanical damage, pathogens, and other environmental stresses.
The coelom also provides a more stable and buffered environment for the organs, allowing for greater adaptability to changing external conditions.
Increased Reproductive Potential: The coelom provides a spacious environment for the development and maturation of reproductive organs, allowing for the production of large quantities of gametes and facilitating fertilization.
It also allows for the development of specialized reproductive structures and behaviors, which can increase the reproductive potential and success of true coelomates.
Greater Body Size and Complexity: The presence of a coelom allows for greater body size and complexity in animals. BZYCT131 Solved Free Assignment 2023
The coelom provides additional space for organs and structures to develop and function, which allows for the evolution of more complex body plans and organ systems.
This is evident in many true coelomates, such as arthropods, mollusks, and vertebrates, which exhibit a wide range of body sizes and complexities.
true coelomates have several advantages compared to animals without a coelom or those with a pseudocoelom.
The presence of a true coelom allows for improved organ development and function, enhanced muscular function, improved circulation and respiration, greater protection and adaptability, increased reproductive potential, and greater body size and complexity.
These advantages have contributed to the success and diversity of true coelomates in the animal kingdom, allowing them to thrive in various habitats and ecological niches. BZYCT131 Solved Free Assignment 2023
- a) Choose the correct word from the alternative given:
i) Trilobites are an extinct group of primitive/advanced arthropods.
ii) Spiders, ticks, mites and scorpions are included under the class Eurypterida/Arachnida.
iii) Spinning organs or spinnerets are characterstic of Araneae/Acarina.
Ans. i) Trilobites are an extinct group of primitive arthropods.
ii) Spiders, ticks, mites, and scorpions are included under the class Arachnida.
iii) Spinning organs or spinnerets are characteristic of Araneae.
b) Indicate whether the following statements are ‘True’ or ‘False’.
i) There are six pairs of appendages in the head of crustaceans corresponding to six segments.
ii) Malacostracans account for over 60% of all the crustaceans.
Ans. i) True BZYCT131 Solved Free Assignment 2023
c) Write short notes on:
i) Compound eye of insects
ii) Moulting in insects
Ans. i) Compound Eye of Insects:
The compound eyes of insects are a unique type of eyes that are composed of numerous individual units called ommatidia.
Each ommatidium functions as a separate visual unit, capable of perceiving light and forming an image.
The compound eyes are situated on the sides of the insect’s head and provide a wide field of vision, allowing insects to detect motion and perceive their surroundings in a panoramic manner.
The structure of a compound eye consists of a cluster of ommatidia, each with its own cornea, lens, and photoreceptor cells.
The cornea acts as a protective covering, while the lens helps in focusing light onto the photoreceptor cells. BZYCT131 Solved Free Assignment 2023
The photoreceptor cells are responsible for detecting light and transmitting visual information to the insect’s brain.
The compound eyes of insects have several advantages. They provide a wide field of vision, allowing insects to detect predators or prey from various directions.
They are also capable of detecting motion, which is essential for insects in their search for food, mates, and shelter.
Additionally, compound eyes are well-adapted for low-light conditions, allowing insects to be active during twilight or nighttime.
ii) Moulting in Insects:
Moulting, also known as ecdysis, is the process by which insects shed their old exoskeleton and replace it with a new one.
Insects have a hard outer covering called the exoskeleton, which provides support, protection, and prevents desiccation.
However, as the insect grows, the exoskeleton becomes rigid and restricts further growth. Moulting is necessary for insects to grow and develop.
The process of moulting is complex and involves several stages. Prior to moulting, an insect undergoes a process of preparation called pre-ecdysis, during which the old exoskeleton is separated from the underlying epidermis.
The insect then secretes a new exoskeleton underneath the old one. Next, the insect takes in air or water to expand its body, causing the old exoskeleton to crack and split. BZYCT131 Solved Free Assignment 2023
The insect then emerges from the old exoskeleton, revealing the new exoskeleton underneath. Once the insect has fully emerged, it expands its new exoskeleton, which then hardens and becomes functional.
Moulting in insects serves several purposes. It allows insects to grow and develop, as they shed their old exoskeleton and replace it with a larger one that accommodates their increased size.
Moulting also allows insects to repair any damage to their exoskeleton, such as injuries or wear and tear.
Additionally, moulting is essential for insects to undergo metamorphosis, the process of transformation from one developmental stage to another, such as from larva to pupa to adult in holometabolous insects.
Overall, moulting is a crucial process in the life cycle of insects, enabling them to grow, develop, and adapt to their environment.
- a) State whether the following statements are ‘True’ or ‘False’:
i) Bivalves have adapted for filter feeding methods.
ii) The blood of cephalopods contains haemocyanin.
iii) Cephalopods have one of the best developed nervous systems among invertebrates.
iv) Development in bivalves includes trochophore and veliger larvae.
i) True – Bivalves, such as clams, mussels, and oysters, have adapted for filter feeding methods. BZYCT131 Solved Free Assignment 2023
They possess specialized structures, such as gills or ctenidia, which allow them to filter out food particles from water, typically plankton or organic matter, and then draw the filtered water into their bodies for obtaining nutrients.
ii) True – The blood of cephalopods, which includes species such as squids, octopuses, and cuttlefish, contains haemocyanin.
Haemocyanin is a copper-containing respiratory pigment that is responsible for transporting oxygen in the blood of cephalopods.
Haemocyanin gives the blood a blue color when oxygenated and a colorless or pale blue color when deoxygenated.
iii) True – Cephalopods have one of the best developed nervous systems among invertebrates. They possess complex brains and well-developed sensory organs, including eyes that are capable of sophisticated vision.
Cephalopods are known for their advanced behaviors, including complex learning, problem-solving, and communication, which are supported by their well-developed nervous system. BZYCT131 Solved Free Assignment 2023
iv) False – Development in bivalves typically includes a trochophore larval stage, which is a free-swimming larva with a band of cilia for locomotion and feeding, but does not include a veliger larval stage.
Veliger larval stage is characteristic of many gastropods (snails) and some other mollusks, but not bivalves.
Bivalves typically develop from fertilized eggs to trochophore larvae, which then undergo metamorphosis and settle onto a substrate, where they develop into juveniles and eventually adults.
b) Fill in the blanks with suitable words:
i) ……………….. is the only living genus under the subclass Nautiloidea.
ii) The mantle is innervated by ……………….. ganglia.
iii) The endoskeleton of most echinoderms is formed of ……………. .
iv) In echinoderms the system of coelomic canals and tube feet is called ………………….., …………………… system.
v) The larval stages of asteroids are ……………… and ………….. .
Ans.i) Nautilus is the only living genus under the subclass Nautiloidea.
ii) The mantle is innervated by pedal ganglia.
iii) The endoskeleton of most echinoderms is formed of calcareous ossicles.
iv) In echinoderms, the system of coelomic canals and tube feet is called the water vascular system. BZYCT131 Solved Free Assignment 2023
v) The larval stages of asteroids are bipinnaria and brachiolaria.
- a) Correct the given statements.
i) Presence of cranium and paired appendages is a characteristic feature of Agnatha.
ii) In jawless fishes heart is a single chambered structure.
iii) Development in hagflshes includes a larval stage called ammocoetes.
iv) Special mucous glands are present in Petromyzon.
Ans. i) Presence of cranium and paired appendages is not a characteristic feature of Agnatha. It is a characteristic feature of Gnathostomata, which includes jawed fishes.
ii) In jawless fishes, the heart is a two-chambered structure, not a single-chambered structure.
iii) Development in hagfishes does not include a larval stage called ammocoetes. Ammocoetes is a larval stage found in lampreys, which are also jawless fishes.
iv) Special mucous glands are not present in Petromyzon. Petromyzon is a genus of lampreys, which are jawless fishes, and they do not possess special mucous glands.
b) Why do marine teleosts need to drink large amounts of seawater?
Ans. b) Marine teleosts need to drink large amounts of seawater because they face the challenge of constantly losing water through their gills due to osmosis.
Seawater is hypertonic compared to the body fluids of marine teleosts, which means that water tends to move out of their bodies and into the seawater through their gills. BZYCT131 Solved Free Assignment 2023
To compensate for this water loss and maintain proper hydration, marine teleosts drink large amounts of seawater to replenish the water they are losing through osmosis.
c) How do the freshwater teleosts overcome their osmoregulatory challenges?
Ans. c) Freshwater teleosts overcome their osmoregulatory challenges by actively taking in water through their gills and specialized cells in their gill epithelium.
They also produce large amounts of dilute urine to get rid of excess water. Additionally, freshwater teleosts have specialized cells in their gill epithelium that actively transport ions, such as sodium and chloride, into their bodies from the surrounding water to maintain proper electrolyte balance.
This helps them to prevent excess water from entering their bodies and maintain the right balance of ions in their internal fluids despite the dilute nature of freshwater.
- i) Describe parental care in amphibians.
Ans. i) Parental care in amphibians:
Parental care refers to the behaviors exhibited by adult amphibians towards their offspring to ensure their survival and well-being.
Amphibians, which include frogs, toads, salamanders, and caecilians, exhibit a wide range of parental care strategies that vary in duration, intensity, and complexity.
In many amphibian species, parental care begins with courtship behaviors, where males compete for females and engage in various displays or calls to attract mates.
Once mating occurs, the female typically lays her eggs in a suitable environment, such as water or damp terrestrial habitats, depending on the species. Here, different forms of parental care can be observed:
Oviposition site selection: Many amphibians exhibit careful selection of oviposition sites, such as water bodies or moist areas with specific characteristics, to ensure the survival of their eggs. BZYCT131 Solved Free Assignment 2023
This may include choosing sites with low predation risk, optimal temperature and humidity levels, and adequate food availability.
Nest building: Some amphibians, such as certain species of frogs and toads, build nests to protect their eggs from predation and environmental conditions.
These nests can be constructed from foam, plant materials, or secreted substances and may provide a safe environment for eggs to develop.
Egg attendance: Some amphibians, particularly certain species of salamanders, actively guard and attend their eggs to prevent predation and provide optimal conditions for their development.
This may involve behaviors such as remaining near the eggs, fanning them to improve oxygen supply, or removing fungal growth.
Brooding: In some amphibian species, such as certain frogs, the female may carry the eggs on her back or in specialized pouches until they hatch. This protects the eggs from predation, desiccation, and other environmental risks.
Larval care: After hatching, some amphibians may continue to provide care to their offspring during the larval stage. BZYCT131 Solved Free Assignment 2023
This can include behaviors such as guarding, transporting, and feeding the larvae until they undergo metamorphosis and become independent juveniles.
Feeding and protection: Once amphibian offspring become independent, adults may continue to provide care by protecting them from predation, guiding them towards suitable habitats, or providing food through regurgitation or direct feeding.
Parental care in amphibians is diverse and can vary greatly depending on the species, environmental conditions, and other factors.
It is often associated with increased survival and reproductive success of the offspring, as it enhances their chances of survival in challenging environments.
ii) Distinguish between anurans and urodeles
Ans. Anurans and urodeles are two major groups of amphibians that are commonly referred to as frogs and salamanders, respectively.
While they share many similarities as amphibians, there are several key differences that distinguish them from each other:
Body shape and locomotion: Anurans generally have a streamlined body shape with short limbs and are well-adapted for jumping and leaping.
They have a large, muscular hindlimb for jumping and swimming, and their forelimbs are modified for burrowing or grasping.
Urodeles, on the other hand, have a more elongated body shape with longer limbs, making them well-suited for crawling or walking.
They have four well-developed limbs of roughly equal size, making them more adept at terrestrial locomotion. BZYCT131 Solved Free Assignment 2023
Tail: Anurans typically have a short tail, while urodeles have a long, often regenerative tail. The tail of urodeles is an important organ for locomotion, balance, and regeneration.
Skin: The skin of anurans is thin, smooth, and glandular, adapted for gas exchange through the process of cutaneous respiration.
Urodeles, on the other hand, have a thicker, more glandular skin that is often covered with scales or granules, and is not as efficient for cutaneous respiration.
Metamorphosis: Anurans undergo a distinct metamorphosis during their development, where they transition from aquatic tadpoles with gills to terrestrial adults with lungs.
Urodeles, on the other hand, typically have a more gradual metamorphosis, with some species skipping the aquatic larval stage altogether and hatching as miniature adults, while others may retain gills throughout their entire life cycle.
Reproduction: Anurans generally lay their eggs in water, and the larvae develop in aquatic habitats.
Urodeles, on the other hand, may lay their eggs in water, on land, or in damp environments, and the larvae may be aquatic or terrestrial, depending on the species.
Regeneration: Urodeles are known for their remarkable regenerative abilities, with many species capable of regenerating lost body parts, including limbs, tails, and even internal organs. BZYCT131 Solved Free Assignment 2023
Anurans, on the other hand, have limited regenerative abilities and are not known for extensive regeneration.
Diversity: Anurans are more diverse in terms of species richness and ecological adaptations, with over 7,000 known species found in a wide range of habitats across the world.
Urodeles, on the other hand, are relatively less diverse, with around 700 known species, and are typically found in freshwater habitats.
- a) Describe the distinguishing features of turtles of Order Testudines.
b) How are tuataras different from lizards?
c) Describe two anatomical features of lizards (including legless members)
that distinguish them from snakes.
d) How do crocodiles and alligators differ from each other?
Ans. Turtles are a unique group of reptiles known for their distinctive features and adaptations.
Order Testudines, commonly known as turtles or tortoises, includes over 350 species of turtles that are distributed across various habitats, from freshwater to marine environments. Here are some distinguishing features of turtles of Order Testudines:
Shell: One of the most distinctive features of turtles is their shell, which is composed of two parts – the dorsal carapace (upper shell) and the ventral plastron (lower shell).
The shell is made of bony plates covered by a layer of keratin, giving it a hard and protective structure that encases the turtle’s body.
The shell serves as a defense mechanism against predators and provides support for the turtle’s body.
Limbs and Feet: Turtles have four limbs, each with five toes, and their feet are adapted to their respective habitats.
Aquatic turtles have webbed feet for swimming, while terrestrial turtles have feet with sturdy claws for walking on land.
Some turtles, like the tortoises, have elephantine limbs adapted for walking on land and digging burrows. BZYCT131 Solved Free Assignment 2023
Head and Neck: Turtles have a distinct head and neck structure. Their head is usually small and has a beak-like mouth with no teeth.
Turtles also have well-developed senses, including excellent vision and hearing. Most turtles have a neck that is retractable into their shell, allowing them to withdraw their head and neck for protection.
Respiration: Turtles have unique respiratory adaptations. Aquatic turtles have specialized glands in their cloaca, called bursae, which allow them to extract oxygen from water.
Terrestrial turtles, on the other hand, have lungs for breathing air, and their ribcage is fused to the carapace, providing protection for their lungs.
Reproduction: Turtles exhibit various reproductive strategies. Most turtles lay eggs, and the temperature during incubation determines the sex of the hatchlings.
Some turtles, like the sea turtles, are known for their long migrations to nesting beaches to lay their eggs. However, some turtles, like the softshell turtles, give birth to live young instead of laying eggs.
Diet: Turtles have diverse diets depending on their habitat and species. Aquatic turtles typically feed on small animals like insects, fish, and aquatic vegetation, while terrestrial turtles may have a more herbivorous diet consisting of plants, fruits, and insects. BZYCT131 Solved Free Assignment 2023
Longevity: Turtles are known for their longevity, with some species living for several decades or even over a century.
This is due to their slow metabolism, efficient respiration, and ability to retract into their shell for protection.
In conclusion, turtles of Order Testudines are characterized by their unique features, including their shell, limbs and feet, head and neck structure, respiratory adaptations, reproductive strategies, diet, and longevity.
These distinguishing features make turtles a fascinating and diverse group of reptiles with remarkable adaptations to their respective habitats.
Ans b) Tuataras, also known as Sphenodon, are reptiles that are native to New Zealand and are distinct from lizards in several ways:
Evolutionary History: Tuataras are considered a living fossil as they are the only surviving species of their order, Rhynchocephalia, which dates back to the time of the dinosaurs.
Lizards, on the other hand, belong to the order Squamata, which includes various lizard species as well as snakes. BZYCT131 Solved Free Assignment 2023
Body Structure: Tuataras have a unique body structure that sets them apart from lizards. Tuataras have a spiny crest running down their back, a relatively larger head, and a shorter tail compared to most lizards.
Lizards, on the other hand, have a more streamlined body with longer tails and a smaller head in proportion to their body size.
Ans c) Lizards, including legless members such as snakes, have several anatomical features that distinguish them from snakes:
Eyelids: Most lizards have movable eyelids, including a transparent lower eyelid that allows them to blink and close their eyes fully.
Snakes, on the other hand, lack movable eyelids and have a clear protective scale, called a spectacle, covering their eyes instead.
External Ears: Many lizards have visible external ears in the form of small holes or openings on the sides of their head.
Snakes, on the other hand, do not have external ears and rely on other sensory organs, such as their forked tongues and specialized hearing structures in their lower jaws, to perceive sound.
Ans d) Crocodiles and alligators are both large, aquatic reptiles that belong to the order Crocodilia, but they have some differences:
Geographic Distribution: Crocodiles are found in different regions around the world, including Africa, Asia, Australia, and the Americas, whereas alligators are primarily found in the United States and China.
Snout Shape: One of the main distinguishing features between crocodiles and alligators is the shape of their snout.
Crocodiles typically have a V-shaped, narrow snout, while alligators have a U-shaped, broader snout. This difference in snout shape is related to their feeding habits and habitats. BZYCT131 Solved Free Assignment 2023
Tooth Visibility: When their mouths are closed, crocodiles have visible teeth on both their upper and lower jaws, even when their mouths are shut.
In contrast, alligators have only their upper teeth visible when their mouths are closed, as their lower teeth are concealed.
Habitat Preferences: Crocodiles tend to prefer saltwater habitats and are known to tolerate more saline environments, while alligators are more commonly found in freshwater habitats, such as swamps, rivers, and lakes.
Behavior: Crocodiles are generally considered more aggressive and can tolerate saltwater habitats, while alligators are known to be less aggressive and tend to prefer freshwater habitats.
- i) Where was the Archaeopteryx discovered? Give reasons for the Archaeopteryx being considered the connecting link between reptiles and birds.
Ans. The Archaeopteryx, also known as the “first bird” or “Urvogel,” is a fossil species that is considered a key transitional form between reptiles and birds.
The first Archaeopteryx fossil was discovered in 1861 in the Solnhofen limestone quarries of Bavaria, Germany, by a collector named Jakob Niemeyer.
Since then, several other specimens of Archaeopteryx have been found in the same region, making it one of the most famous and well-studied fossils in the field of paleontology.
There are several reasons why Archaeopteryx is considered the connecting link between reptiles and birds: BZYCT131 Solved Free Assignment 2023
Anatomical Features: The anatomy of Archaeopteryx exhibits a combination of reptilian and avian features, which provides evidence for its transitional nature.
For example, it has reptilian characteristics such as teeth, a long bony tail, and clawed fingers on its wings, similar to those found in reptiles.
At the same time, it also possesses bird-like features such as feathers, a beak, and hollow bones, which are typical of modern birds.
Flight Capabilities: The fossilized feathers of Archaeopteryx provide strong evidence of its ability to fly, albeit in a more primitive form compared to modern birds.
The feathers are asymmetrical, with a well-developed vane on one side and a narrower vane on the other, which is similar to the flight feathers of birds.
This suggests that Archaeopteryx had the necessary adaptations for powered flight, although it may not have been as agile or efficient in flight as modern birds.
Bone Structure: The bones of Archaeopteryx also show characteristics that are intermediate between reptiles and birds.
For example, its bones are hollow, a feature typical of birds, but they lack some of the specialized adaptations for flight found in modern birds, such as a keeled sternum for attachment of flight muscles.
Teeth: Unlike modern birds, which lack teeth, Archaeopteryx had teeth in its jaws, which is a reptilian characteristic. BZYCT131 Solved Free Assignment 2023
The teeth of Archaeopteryx resemble those of small theropod dinosaurs, suggesting a close evolutionary relationship between birds and dinosaurs.
Claws on Wings: Another reptilian feature seen in Archaeopteryx is the presence of three fingers on its wings, each with a sharp claw.
This is in contrast to modern birds, which have reduced their fingers and have only a single finger (the thumb) with a small claw. This suggests that Archaeopteryx retained some reptilian characteristics in its wing structure.
Similar Skeletal Structure: The skeletal structure of Archaeopteryx is similar to that of theropod dinosaurs, particularly the family Dromaeosauridae.
Features such as the elongated arms, grasping hands with sharp claws, and a long bony tail are reminiscent of its reptilian ancestors.
Shared Evolutionary Traits: Studies of the fossil record and comparative anatomy have shown that Archaeopteryx shares several evolutionary traits with both reptiles and birds.
For example, it shares skeletal characteristics with small theropod dinosaurs, particularly those related to the shoulder girdle, pelvis, and hind limbs.
At the same time, it shares avian features such as feathers, a beak, and a wishbone with modern birds.
ii) Explain the role of drag and thrust in bird flight.
Ans. Bird flight is a complex and fascinating phenomenon that involves various aerodynamic principles, including drag and thrust.
Drag refers to the resistance that air exerts on an object moving through it, while thrust refers to the force that propels an object forward.
In bird flight, drag and thrust play critical roles in enabling birds to achieve and maintain flight.BZYCT131 Solved Free Assignment 2023
Drag is a significant factor in bird flight, as birds need to overcome the resistance of air as they move through it. There are two main types of drag that birds encounter during flight: form drag and induced drag.
Form drag is the result of the shape of the bird’s body and wings, and it increases with the bird’s speed.
Birds have evolved streamlined bodies and wings to minimize form drag and reduce the resistance of air as they move through it.
The streamlined shape of a bird’s body and wings allows the air to flow smoothly over them, reducing turbulence and minimizing drag.
Induced drag, on the other hand, is the result of the lift that birds generate to stay airborne. When a bird’s wings generate lift, it creates a pressure difference between the upper and lower surfaces of the wings.
This pressure difference results in air flowing from the high-pressure region (lower surface) to the low-pressure region (upper surface) of the wings, creating vortices or swirling air currents at the wingtips.
These vortices generate induced drag, which is a byproduct of lift.
Birds have evolved various strategies to minimize induced drag. One such strategy is wingtip slotting, which involves having gaps or slots at the tips of the wings.
These gaps allow the air from the upper surface of the wing to flow through to the lower surface, reducing the strength of the vortices and minimizing induced drag.
Additionally, birds often change the shape of their wings during flight, adjusting the angle of attack and the curvature of the wings to optimize lift and reduce drag.
Thrust, on the other hand, is the force that propels a bird forward through the air. Thrust is generated by the flapping motion of a bird’s wings, as the bird pushes air backward with each downstroke and propels itself forward.
The shape, size, and angle of attack of a bird’s wings, as well as the strength and timing of its wing beats, play a crucial role in generating thrust.
Thrust must be greater than drag for a bird to achieve and maintain forward flight.
Birds also use other techniques to generate thrust, such as gliding and soaring. Gliding involves using gravity to descend while minimizing drag, and soaring involves using rising air currents, such as thermals or updrafts, to gain altitude and maintain flight without much flapping.
These techniques allow birds to minimize the energy expenditure required for flight and optimize their flight performance. BZYCT131 Solved Free Assignment 2023
- a) State whether the following statements are True (T) or False (F).
i) Elephants are the largest land animals.
ii) Blubber is found in monkeys.
iii) Carnivores are grass eating mammals.
iv) Kangaroos are egg laying mammals.
v) Monotremes are viviparous.
Ans. i) False (F). Elephants are the largest land animals.
ii) False (F). Blubber is not found in monkeys. Blubber is a layer of thick fat that is found in marine mammals, such as whales, seals, and walruses, to help them survive in cold environments.
iii) False (F). Carnivores are meat-eating mammals. They primarily feed on other animals.
iv) False (F). Kangaroos are not egg-laying mammals. They are marsupials, which means they give birth to relatively undeveloped young, which then continue to develop and grow in a pouch on the mother’s belly.
v) False (F). Monotremes are not viviparous. Monotremes are a unique group of mammals that lay eggs instead of giving birth to live young. Examples of monotremes include the platypus and the echidna.
b) Differentiate between Artiodactyla and Perissodactyla.
Ans. Artiodactyla and Perissodactyla are two different orders of mammals that are differentiated based on the number of toes they have on their feet and some other anatomical features.
Artiodactyla are mammals that have an even number of toes on their feet (typically two or four).
They are herbivorous mammals that include animals like cows, deer, pigs, giraffes, hippos, and camels.
Artiodactyls typically have a complex four-chambered stomach to aid in digestion of plant material.
They have an elongated skull, with a large diastema (gap) between their front teeth and cheek teeth. BZYCT131 Solved Free Assignment 2023
Artiodactyls typically have well-developed hooves for terrestrial locomotion.
Perissodactyla are mammals that have an odd number of toes on their feet (typically one, three, or five).
They are herbivorous mammals that include animals like horses, zebras, tapirs, and rhinoceroses.
Perissodactyls have a simple stomach compared to the complex four-chambered stomach of artiodactyls.
They have a unique foot structure where the weight-bearing toe is either the third toe (in horses and zebras) or the third and fourth toes (in tapirs and rhinoceroses).
Perissodactyls typically have a large body size and are well-adapted to running.
c) Give one distinguishing morphological feature of each of the following
Ans.Distinguishing morphological features of the following orders:
i) Cingulata (Order Cingulata):
Cingulata are a group of mammals that includes armadillos.
One distinguishing morphological feature of Cingulata is the presence of a protective armor made of bony plates on their dorsal side.
These bony plates are formed by fused dermal bones and provide defense against predators. BZYCT131 Solved Free Assignment 2023
Armadillos also have sharp, curved claws for digging and a long tongue for feeding on insects.
ii) Sirenia (Order Sirenia):
Sirenia are a group of aquatic mammals that includes manatees and dugongs.
One distinguishing morphological feature of Sirenia is their fusiform body shape, which is streamlined for efficient swimming in water.
They have paddle-like flippers and lack hind limbs, and their forelimbs are modified into flippers for swimming.
Sirenia also have a large, horizontally flattened tail for propulsion in water.
iii) Primate (Order Primates):
Primates are a group of mammals that includes humans, monkeys, and apes.
One distinguishing morphological feature of primates is their highly developed brain, relative to body size, which is responsible for their complex social behaviors and problem-solving abilities. BZYCT131 Solved Free Assignment 2023
Primates typically have grasping hands and feet with opposable thumbs, which allow for precise and coordinated movements.
Primates also have forward-facing eyes with stereoscopic vision, which provides depth perception and enhances their ability to judge distances accurately.