What is living? Questions in English

(D) Living organisms are characterized by self-replication,evolution,and self-regulating interactive systems.
Non-living objects do not possess these biological properties.
However,non-living objects like mountains,boulders,and sand mounds can show growth by the accumulation of material on their surface.
This type of growth is external and reversible,unlike the internal and irreversible growth seen in living organisms.

(D) Growth in non-living objects is extrinsic,meaning it occurs by the accumulation of material on the surface. This process is reversible and not an internal biological process. Therefore,the statement that growth in non-living objects is intrinsic is false,as intrinsic growth is a characteristic feature of living organisms.

(C) Growth is defined as an increase in mass and number of individuals. In living organisms,growth occurs from within,which is known as intrinsic growth. Non-living objects can also show growth (e.g.,mountains,boulders,sand mounds) by the accumulation of material on their surface,which is known as extrinsic growth. Therefore,intrinsic growth is a characteristic feature of all living organisms.

(B) In unicellular organisms,growth and reproduction are mutually inclusive events.
When these organisms increase in cell number,they are simultaneously reproducing.
Examples of such organisms include desmids,diatoms,and protozoans.

(D) The defining property of living organisms that distinguishes them from non-living things without any exception is the ability to respond to their environment (consciousness or responsiveness).
- $A$: Interaction with the environment is a broad trait,but responsiveness is the specific defining feature.
- $B$: Reproduction is not an unexceptional characteristic because some living organisms like sterile worker bees or infertile human couples do not reproduce.
- $C$: Growth is also seen in non-living things (e.g.,crystal growth,mountain growth),so it is not a defining feature.
- $D$: Responsiveness to stimuli (touch,light,temperature,etc.) is a property shown by all living organisms,making it the most accurate choice among the given options.

(A) The process of maintaining a constant internal environment despite changes in external environmental conditions is known as $Homeostasis$.
$Epistasis$ refers to a genetic interaction where one gene masks or interferes with the expression of another gene.
$Heterosis$ (or hybrid vigour) refers to the phenomenon where the progeny of a cross between two genetically different parents shows superior traits compared to the parents.
$Antibiosis$ is a type of $Amensalism$ (interaction type $-; 0$) where one organism produces substances that are harmful to another organism.

(N/A) Non-living objects can exhibit growth,but this is fundamentally different from the growth observed in living organisms.
In non-living things,such as mountains,boulders,or sand dunes,growth occurs due to the accumulation of material on their external surfaces. This is known as external growth or accretion.
In contrast,living organisms exhibit internal growth,where cells divide and increase in mass from within. Therefore,growth cannot be considered a defining property of living organisms because it is not exclusive to them.

(N/A) In unicellular organisms like $Amoeba$,mitotic cell division is a means of reproduction (multiplication) because it increases the number of individuals.
In multicellular organisms,mitotic cell division is a means of growth because it increases the number of cells within the same organism.

(D) To identify living things,we conventionally look for distinctive characteristics exhibited by living organisms.
Growth,reproduction,the ability to sense the environment,and response to stimuli are unique features of living organisms.
Additionally,features such as metabolism,the ability to self-replicate,self-organize,interact,and emergence are also characteristic of living systems.

(B) Growth is a defining characteristic of all living organisms.
In unicellular organisms,growth and reproduction are synonymous.
These organisms grow by cell division (mitosis),which increases the number of individuals in the population.
Therefore,for unicellular organisms,the parameter for growth is an increase in cell number rather than an increase in cell size or volume.

(B) Growth is defined as an irreversible increase in the size or mass of an organism or its parts.
In living organisms,growth is characterized by two main aspects:
$1$. Increase in mass $(V)$
$2$. Increase in number of individuals $(I)$
These two are often referred to as the twin characteristics of growth.
Therefore,the correct option is $B$.

(A) In multicellular organisms,growth occurs through cell division,which increases the number of cells in the body.
In unicellular organisms,cell division is the mechanism by which they increase their population size,and it is also considered a mode of growth as it leads to an increase in the total biomass of the organism.
Therefore,both multicellular and unicellular organisms exhibit growth through cell division.

(C) Growth is a characteristic feature of living organisms,where it occurs from within. However,non-living objects like mountains,boulders,and sand mounds also grow by the accumulation of material on their surface. Therefore,growth is observed in both living and non-living entities,although the mechanism of growth differs (intrinsic in living,extrinsic in non-living).

(D) Reproduction is a characteristic feature of living organisms,but it is not an all-inclusive defining characteristic.
$1$. Worker bees are sterile females that do not reproduce.
$2$. Many human couples are infertile and cannot produce offspring.
$3$. Mules are the sterile offspring of a male donkey and a female horse,and they cannot reproduce.
Since all these examples represent living organisms that are unable to reproduce,the correct answer is $D$.

(A) In multicellular organisms,growth and reproduction are distinct and mutually exclusive events. Growth refers to an increase in mass or number of cells,while reproduction is the process of producing offspring. In contrast,in unicellular organisms,cell division (growth) is synonymous with reproduction.

(D) Living organisms possess the ability to sense their surroundings or environment and respond to these environmental stimuli. These stimuli can be $Physical$,$Chemical$,or $Biological$. For example,plants respond to light (physical),water (chemical),and other organisms (biological). Therefore,all these factors contribute to the sensory response of living beings.

(B) In biological systems,properties of higher levels of organization (like tissues) are not present in the constituent lower levels (like individual cells). Instead,these properties emerge due to the interactions among the constituent components. Therefore,the properties of tissues arise as a result of interactions among the constituent cells.

(D) Living organisms possess the ability to sense their environment and respond to environmental stimuli,which could be physical,chemical,or biological.
$1$. Physical factors include light,temperature,and water.
$2$. Biological factors include other organisms.
$3$. Chemical factors include pollutants.
Since all these factors affect the living organism and it responds to them,the correct answer is $D$.

(B) The biological organization follows a hierarchical structure starting from the simplest level to the most complex level.
$1$. The fundamental building blocks are atoms,which combine to form molecules.
$2$. Molecules form subcellular structures (organelles),which constitute the cell.
$3$. Cells group together to form tissues,and tissues organize into organs.
$4$. Organs work together to form an organism.
Therefore,the correct sequence is: Atom $\rightarrow$ Molecule $\rightarrow$ Subcellular $\rightarrow$ Cellular $\rightarrow$ Tissue $\rightarrow$ Organ $\rightarrow$ Organism.

(A) Nomenclature is the process of providing standardized names to organisms such that a particular organism is known by the same name all over the world. This is done based on specific rules and principles,such as the International Code for Botanical Nomenclature $(ICBN)$ or International Code for Zoological Nomenclature $(ICZN)$.

(B) Identification is the process of correctly recognizing an organism and associating it with a specific name that has already been established through nomenclature. It involves comparing the organism with known specimens to determine its identity.

(C) The term $Systematics$ is derived from the $Latin$ word $Systema$,which means systematic arrangement of organisms. $Linnaeus$ used $Systema$ $Naturae$ as the title of his publication.

(A) Organisms like plants,animals,and fungi exhibit a vast diversity in their external morphology,internal anatomy,and physiological processes due to their different evolutionary lineages and environmental adaptations. However,despite these differences,they all share a common pattern of sexual reproduction,which involves the formation of haploid gametes,their fusion to form a diploid zygote,and subsequent development. Thus,they differ in $P$ (Morphology,Physiology,and Anatomy) and show similarities in $Q$ (Sexual reproduction).

(B) The statement in option $B$ is incorrect. When we observe objects in our immediate surroundings,the light travels from them to our eyes almost instantaneously,so we perceive them as they exist in the present. In contrast,stars are at such vast distances (billions of kilometers) that the light takes years to reach us,meaning we are indeed looking at the past when we observe them. Therefore,the claim that nearby objects are seen as they were in the past is scientifically inaccurate in the context of human perception.

(D) The distance between stars is vast,making standard units like meters or kilometers impractical.
Astronomers use the 'Light-year' as a unit of distance.
$A$ light-year is defined as the distance that light travels in a vacuum in one Julian year.
$1 \text{ light-year} \approx 9.46 \times 10^{12} \text{ km}$.

(A) Reductionist Biology is an approach that attempts to understand the complexity of living organisms by breaking them down into their constituent parts and studying their physico-chemical properties. This method focuses on the molecular and cellular levels to explain biological phenomena,essentially viewing life as a result of physico-chemical interactions.

(A) Ernst Mayr $(1904-2005)$,a Harvard University evolutionary biologist,was awarded the $1999$ Crafoord Prize. He is often referred to as 'The Darwin of the $20^{th}$ century' for his significant contributions to the field of evolutionary biology and his work on the biological species concept.

(A) In unicellular organisms,growth and reproduction are synonymous because they increase in cell number to reproduce. However,in multicellular organisms,growth and reproduction are mutually exclusive events. Growth refers to an increase in mass and number of individuals,while reproduction is the process of producing offspring. Therefore,the statement '$A$' is incorrect.

(A) The properties of cellular organelles are not present in the molecular constituents of the organelles themselves but arise as a result of interactions among the molecular components comprising the organelle. This is a fundamental principle of emergent properties in biological systems. Therefore,statement $A$ is false. Statements $B$,$C$,and $D$ are scientifically accurate descriptions of biological concepts.