Textbook - DIVERSITY IN LIVING ORGANISMS Questions in English

(N/A) There are millions of organisms on this Earth. It is extremely difficult to study each organism individually. Therefore,we identify similarities and differences among them and group them into different categories. Classification makes the study of such a vast diversity of life forms systematic,organized,and easier.

(N/A) Examples of the range of variations observed in daily life are:
$1$. Size: Organisms vary greatly in size,ranging from microscopic bacteria to massive organisms like elephants,whales,and large trees.
$2$. Colour: The colour of various animals differs significantly. Some worms are colourless or transparent,while plants exhibit a wide variety of pigments.
$3$. Life span: The life span of different organisms is also quite varied. For example,a crow lives for only $15$ years,whereas a parrot can live for about $140$ years.

(B) The more basic characteristic for classifying organisms is the kind of cells they are made of.
This is because organisms living in the same habitat (e.g.,water) can have vastly different cellular structures (e.g.,prokaryotic bacteria vs. eukaryotic fish).
The kind of cells (prokaryotic vs. eukaryotic,unicellular vs. multicellular) determines the fundamental biological processes and evolutionary relationships of an organism,making it a more reliable and basic criterion for classification than the habitat.

(A) The primary characteristic on which the broad division of organisms is made is the nature of the cell,specifically whether it is a $prokaryotic$ or $eukaryotic$ cell. This distinction forms the basis for the highest level of classification,separating organisms into those with simple,unorganized nuclei and those with complex,membrane-bound nuclei.

(D) Plants and animals are classified into different categories primarily based on their $Mode$ of $nutrition$.
Plants are $autotrophs$, meaning they synthesize their own food through photosynthesis.
In contrast, animals are $heterotrophs$, meaning they depend on other organisms for their food.
Additionally, other fundamental differences include the presence of a rigid cell wall in plants (absent in animals), the presence of chloroplasts in plants, and the ability of animals to exhibit $locomotion$.

(N/A) primitive organism is one that possesses a simple body structure and an ancient body design or features that have not changed significantly over a long period of time.
In terms of body design,primitive organisms are characterized by simple structures,whereas so-called advanced organisms possess complex body structures and higher levels of biological organization.

(A) Yes,advanced organisms are generally considered complex organisms.
Evolutionary history shows that life progressed from simple,primitive forms to more complex,advanced forms.
Advanced organisms have acquired their complexity over a long period of evolutionary time.
This complexity allows them to adapt better,compete,and survive in changing environments.

(C) The primary criterion for classifying organisms into Kingdom $Monera$ or Kingdom $Protista$ is their cellular structure.
Organisms in Kingdom $Monera$ are unicellular and prokaryotic,meaning they lack a well-defined nucleus and membrane-bound organelles.
Organisms in Kingdom $Protista$ are unicellular and eukaryotic,meaning they possess a well-defined nucleus and membrane-bound organelles.

(B) The organism described is single-celled,eukaryotic,and photosynthetic.
According to the five-kingdom classification system,these characteristics are defining features of the Kingdom Protista.
Specifically,unicellular photosynthetic eukaryotes like diatoms,dinoflagellates,and euglenoids are classified under Kingdom Protista.

(A) In the hierarchy of classification,the $Species$ is the basic unit and contains the smallest number of organisms that share the maximum number of common characteristics.
Conversely,the $Kingdom$ is the highest category in the taxonomic hierarchy and contains the largest number of organisms with the least number of common characteristics.

(A) The division $Thallophyta$ consists of the simplest plants. These organisms do not have a well-differentiated body structure,meaning their body is not differentiated into roots,stems,and leaves. They are predominantly aquatic and are commonly referred to as algae.

(N/A)

Pteridophyta	Phanerogams
They have inconspicuous or less differentiated reproductive organs.	They have well-developed reproductive organs.
They produce naked embryos called spores.	They produce seeds.
Examples include ferns,Marsilea,and Equisetum.	Examples include Pinus,Cycas,and fir.

(N/A)

Gymnosperm	Angiosperm
They are non-flowering plants.	They are flowering plants.
Naked seeds not enclosed inside fruits are produced.	Seeds are enclosed inside fruits.
$Pinus$,$Cedar$,$fir$,$Cycas$,etc.,are examples.	$Coconut$,$palm$,$mango$,etc.,are examples.

(N/A)

Porifera	Coelenterata
They are mostly marine, non-motile, and found attached to rocks.	They are aquatic, mostly marine, and can be sessile or free-swimming.
They exhibit a cellular level of organization.	They exhibit a tissue level of organization.
The body has pores (ostia) and a central cavity called spongocoel.	The body has a central gastrovascular cavity with a single opening called the hypostome.
Examples: $Spongilla$, $Euplectella$, $Sycon$.	Examples: $Hydra$, $Sea \text{ } anemone$, $Corals$.

(B) The primary differences between annelids and arthropods are as follows:

$1$. Annelids possess a closed circulatory system, whereas arthropods possess an open circulatory system.

$2$. The body of annelids is divided into many identical segments (metamerism), while the body of arthropods is divided into a few specialized segments (tagmatization).

(C)

< strong>Amphibian	< strong>Reptiles
They have a dual mode of life (aquatic and terrestrial).	They are completely terrestrial.
Skin is moist and scales are absent.	Skin is dry and covered with scales.
They lay eggs in water.	They lay eggs on land.
Examples include frogs,toads,and salamanders.	Examples include lizards,snakes,turtles,and chameleons.

(N/A)

$Aves$	$Mammalia$
$Aves$ possess feathers and a beak.	$Mammals$ do not have feathers and lack a beak.
They are oviparous (egg-laying).	They are mostly viviparous (give birth to young),though some are oviparous.
They have pneumatic (hollow) bones to aid in flight.	They possess mammary glands to nourish their young.

(N/A) The advantages of classifying organisms are as follows:
$1$. It provides information regarding the diversity of plants and animals.
$2$. It makes the study of different kinds of organisms much easier and systematic.
$3$. It reveals the inter-relationships among various organisms.
$4$. It helps in understanding the evolutionary history and relationships of organisms.
$5$. It facilitates the development of other life sciences.
$6$. It assists environmentalists in developing new methods for the conservation of biodiversity.

(N/A) To develop a hierarchy in classification,we choose characteristics that are more fundamental and basic.
$1$. The first characteristic chosen is the one that forms the broadest group and is present in the largest number of organisms.
$2$. The subsequent characteristics are chosen based on how they further differentiate the organisms within the already established groups.
$3$. Essentially,we select a characteristic that depends on the previous one and helps in creating a more specific and detailed classification.

(N/A) The basis for grouping organisms into five kingdoms are:
$1$. Complexity of cell structure: Organisms are classified based on whether they are $Prokaryotic$ (lacking a defined nucleus) or $Eukaryotic$ (having a well-defined nucleus).
$2$. Body organization: Organisms are categorized as $Unicellular$ (single-celled) or $Multicellular$ (many-celled),which significantly impacts their physiological complexity.
$3$. Presence or absence of cell wall: The presence of a rigid cell wall is a key feature used to distinguish between plants,fungi,and certain protists versus animals.
$4$. Mode of nutrition: Organisms are classified based on how they obtain food,primarily into $Autotrophic$ (synthesizing their own food,e.g.,plants) and $Heterotrophic$ (obtaining food from external sources,e.g.,animals and fungi).

(N/A) The major divisions in Kingdom Plantae are:
$1$. Thallophyta
$2$. Bryophyta
$3$. Pteridophyta
$4$. Gymnosperms
$5$. Angiosperms
The basis for these divisions includes the following criteria:
- Whether the plant body is well-differentiated into distinct components like roots,stems,and leaves.
- Whether the plant body possesses specialized vascular tissues ($xylem$ and $phloem$) for the transport of water and nutrients.
- The ability of the plant to produce seeds.
- Whether the seeds are enclosed within fruits (ovary) or are naked.

(N/A) The characteristics used to classify plants are different from those used for animals because their basic body designs differ significantly,based on the need to produce their own food (plants) or acquire food (animals).
Criteria for deciding divisions in plants include:
$1$. Whether the plant body is differentiated or undifferentiated.
$2$. Presence or absence of specialized vascular tissues.
$3$. Ability to bear seeds (with or without seeds).
$4$. If seeds are present,whether they are naked or enclosed within fruits.
Animals cannot be classified using these criteria because their fundamental body plans are distinct from plants. Animals are instead classified based on their specific body structure,such as the presence of a notochord,symmetry,levels of organization,and the presence of a coelom.

(A) Animals in Vertebrata are classified into five main classes:
$(i)$ Class Pisces: This class includes fish such as $Scoliodon$,tuna,rohu,shark,etc. These animals are aquatic. They possess adaptive features like a streamlined body,a tail for movement,and gills for respiration.
$(ii)$ Class Amphibia: This includes frogs,toads,and salamanders. They have a dual mode of life. In the larval stage,they respire through gills,while in the adult stage,respiration occurs through lungs or skin. They lay eggs in water.
$(iii)$ Class Reptilia: This includes reptiles like lizards,snakes,and turtles. They typically creep or crawl on land. Their body is covered with dry,cornified skin to prevent water loss,and they lay eggs on land.
$(iv)$ Class Aves: This includes all birds such as sparrows,pigeons,and crows. Most possess feathers. Their forelimbs are modified into wings for flight,while hind limbs are adapted for walking and clasping. They lay eggs.
$(v)$ Class Mammalia: This includes animals that possess milk-producing (mammary) glands to nourish their young. Some lay eggs,while others give birth to live young. Their skin features hair,sweat glands,and oil glands to regulate body temperature.