Mix Example-Cell: The Unit of Life Questions in English

(C) The correct matches are as follows:
$(1)$ Endoplasmic Reticulum: $(U)$ Synthesis of lipids (specifically Smooth $ER$).
$(2)$ Golgi apparatus: $(S)$ Site of synthesis of glycolipids and glycoproteins.
$(3)$ Chloroplast: $(T)$ Performs photosynthesis.
$(4)$ Mitochondria: $(P)$ Provides energy $(ATP)$ for various cell functions.
$(5)$ Lysosomes: $(R)$ Surrounded by a single membrane.
$(6)$ Centriole: $(Q)$ Involved in the formation of basal bodies.
Thus, the correct sequence is $(1-U), (2-S), (3-T), (4-P), (5-R), (6-Q)$.

(A) The correct matches are as follows:
$(1)$ Microfilaments are composed of the protein $Actin$ $(Q)$.
$(2)$ Microtubules are composed of the protein $Tubulin$ $(R)$.
$(3)$ Bacterial flagella are composed of the protein $Flagellin$ $(S)$.
$(4)$ The bacterial outer layer is known as the $Glycocalyx$ $(P)$.
Therefore, the correct sequence is $(1-Q), (2-R), (3-S), (4-P)$.

(A) The correct matches are as follows:
$(1)$ Motile bacteria possess flagella, which are composed of the protein flagellin. Thus, $(1-R)$.
$(2)$ Glycocalyx in bacteria can exist as a loose sheath called the slime layer or a thick, tough layer called the capsule. Thus, $(2-P)$.
$(3)$ Gas vacuoles are found in prokaryotes like blue-green algae and purple and green photosynthetic bacteria (autotrophic bacteria) to provide buoyancy. Thus, $(3-S)$.
$(4)$ Ribosomes in prokaryotes are $70S$ type, and their diameter is approximately $20 \, nm$. Thus, $(4-Q)$.
Therefore, the correct sequence is $(1-R), (2-P), (3-S), (4-Q)$.

(D) The correct matches are as follows:
$(1)$ Mitochondria are known as the 'Powerhouse of the cell' because they generate $ATP$, so $(1-S)$.
$(2)$ Chloroplasts are the sites of photosynthesis in plants, so $(2-R)$.
$(3)$ Lysosomes contain hydrolytic enzymes and are known as 'Suicide bags', so $(3-P)$.
$(4)$ Smooth Endoplasmic Reticulum $(SER)$ is primarily involved in the synthesis of lipids and steroids, so $(4-Q)$.
Therefore, the correct sequence is $(1-S), (2-R), (3-P), (4-Q)$.

(A) The correct matching is as follows:
$(1)$ Vacuole: Maintains turgor pressure in plant cells $(S)$.
$(2)$ Nucleus: It is absent in mature human erythrocytes (RBCs) $(P)$.
$(3)$ Nuclear envelope: It is a double membrane structure; however, prokaryotes lack a defined nucleus and thus lack a nuclear envelope $(Q)$.
$(4)$ Nucleolus: It is the site for active synthesis of $rRNA$ $(R)$.
Therefore, the correct sequence is $(1-S), (2-P), (3-Q), (4-R)$.

(D) Assertion $(A)$ is false because not all organelles in a eukaryotic cell are membrane-bound; for example,ribosomes are non-membrane-bound organelles found in eukaryotic cells.
Reason $(R)$ is true because prokaryotic cells lack membrane-bound organelles,and their structures like ribosomes are also non-membrane-bound.
Therefore,$A$ is false and $R$ is true.

(C) The figure shows a bacterial cell. The structure labeled as $A$ is the flagellum.
Bacterial flagella are primarily composed of a protein called flagellin.
Therefore,the correct answer is protein.

(B) In the provided diagram of an animal cell:
$1$. Label $a$ points to the stack of flattened,membrane-bound sacs known as the Golgi apparatus.
$2$. Label $b$ points to the dense,spherical structure located inside the nucleus,which is the nucleolus.
Therefore,the correct identification is $a -$ Golgi apparatus and $b -$ Nucleolus.

(A) The cell is considered the fundamental unit of life and a biological marvel because it possesses the ability to perform metabolic activities,such as converting nutrients into free energy $(ATP)$ through processes like cellular respiration.
Additionally,the cell contains genetic material $(DNA)$ which stores the information necessary for its structure,function,and reproduction.
Therefore,both the assertion and the reason are scientifically accurate,and the reason provides a valid explanation for why the cell is considered a marvel of life.

(C) The correct answer is $C$.
$1$. Flagella are hair-like extensions of the cell membrane that arise from the basal body in both prokaryotic and eukaryotic cells.
$2$. Cilia are also hair-like outgrowths of the cell membrane that arise from the basal body.
$3$. Pili are elongated tubular structures made of a special protein called pilin,which are found in bacteria. They are surface appendages and do not arise from a basal body.
Therefore,the statement that pili arise from the basal body is incorrect.

(A) The correct matching is as follows:
$(1)$ Mesosome: These are infoldings of the cell membrane in prokaryotes,which help in respiration and cell wall formation. Thus,$(1-d)$.
$(2)$ Peroxisome: These are microbodies that are not part of the endomembrane system. Thus,$(2-a)$.
$(3)$ Polysome: $A$ structure formed when many ribosomes are associated with a single $m-RNA$ molecule. Thus,$(3-b)$.
$(4)$ Lysosome: These are membrane-bound vesicular structures formed by the process of packaging in the Golgi apparatus and are single membrane-bound organelles. Thus,$(4-c)$.
Therefore,the correct sequence is $(1-d, 2-a, 3-b, 4-c)$.

(C) The endomembrane system includes organelles whose functions are coordinated,such as the endoplasmic reticulum $(ER)$,Golgi complex,lysosomes,and vacuoles.
Organelles like mitochondria,chloroplasts,and peroxisomes are not part of the endomembrane system because their functions are not coordinated with the above-mentioned components.
In option $C$,both peroxisomes and mitochondria are not part of the endomembrane system.

(A) The endomembrane system includes the endoplasmic reticulum,Golgi complex,lysosomes,and vacuoles.
In the given diagram:
$A$ represents the mitochondria.
$B$ represents the rough endoplasmic reticulum.
$C$ represents the plasma membrane (or a vesicle).
$D$ represents the Golgi apparatus.
Since the mitochondria are not part of the endomembrane system,the correct option is $A$.

(B) In the provided diagram of a plant cell,the label $X$ points to the dense,central structure within the cell,which is the nucleus. The label $Y$ points to an organelle containing internal lamellar structures characteristic of a chloroplast,which is the site of photosynthesis in plant cells. Therefore,$X$ is the nucleus and $Y$ is the chloroplast.

(B) Statement $P$ is false because the middle lamella is primarily composed of calcium and magnesium pectates,not cellulose.
Statement $Q$ is false because the formation of gametes (gametogenesis) typically involves meiosis,not mitosis,to ensure the reduction of chromosome number to haploid $(n)$.
Therefore,both statements are false.

(D) cell is the fundamental structural and functional unit of life. It is composed of various organelles (such as mitochondria,ribosomes,endoplasmic reticulum,etc.) which are specialized structures that perform specific functions. These organelles are themselves built from complex biomolecules (such as proteins,lipids,carbohydrates,and nucleic acids). Therefore,both organelles and biomolecules are essential components that participate in the formation and maintenance of a cell.

(D) Nucleoproteins are proteins that are structurally associated with nucleic acids (either $DNA$ or $RNA$).
$1$. The $Nucleus$ contains chromatin, which is a complex of $DNA$ and histone proteins.
$2$. $Chromosomes$ are condensed forms of chromatin, consisting of $DNA$ and proteins.
$3$. $Ribosomes$ are composed of ribosomal $RNA$ $(rRNA)$ and ribosomal proteins.
Since all three structures are composed of nucleoproteins, the correct answer is $D$.

(C) The biological hierarchy of organization starts from the simplest level and progresses to more complex levels.
$1$. The sequence is: $\text{Subatomic particles} \rightarrow \text{Atoms} \rightarrow \text{Molecules} \rightarrow \text{Organelles} \rightarrow \text{Cells} \rightarrow \text{Tissues} \rightarrow \text{Organs} \rightarrow \text{Organ systems} \rightarrow \text{Organism}$.
$2$. Comparing this with the given sequence $(P) \rightarrow \text{Subatomic particles} \rightarrow \text{Atoms} \rightarrow \text{Molecules} \rightarrow (Q) \rightarrow \text{Cells} \rightarrow \text{Tissues}$,it is clear that the sequence provided in the question is slightly different in its starting point.
$3$. However,looking at the options,$(P)$ represents the fundamental components (Subatomic particles) and $(Q)$ represents the structure formed after molecules but before cells,which is Organelles.
$4$. Therefore,$(P)$ is Subatomic particles and $(Q)$ is Organelles.

(B) The cell is the fundamental structural and functional unit of life. The organization of a cell is primarily maintained by its plasma membrane,which acts as a selective barrier,and various membranous organelles (such as the nucleus,mitochondria,endoplasmic reticulum,etc.) that compartmentalize cellular functions. Tissues and organs are higher levels of biological organization formed by groups of cells,not components of a single cell's internal organization.

(A) Statement $(A)$ is true: Mitochondria and chloroplasts are known as semi-autonomous organelles because they possess their own genetic material $(DNA)$ and ribosomes.
Statement $(B)$ is false: While these organelles are formed by the division of pre-existing organelles,they do not lack protein-synthesizing machinery. They contain their own $DNA$,$mRNA$,$tRNA$,$rRNA$,and ribosomes,which allow them to synthesize some of their own proteins.
Therefore,$(A)$ is true but $(B)$ is false.

(D) The correct matching is as follows:
$A$. Thylakoids: These are flattened membranous sacs found within the stroma of chloroplasts,involved in light-dependent reactions $(iii)$.
$B$. Cristae: These are the infoldings of the inner mitochondrial membrane that increase the surface area for cellular respiration $(iv)$.
$C$. Cisternae: These are the disc-shaped,flattened sacs that make up the Golgi apparatus $(i)$.
$D$. Chromatin: This is the condensed,thread-like structure of $DNA$ and proteins found in the nucleus $(ii)$.
Therefore,the correct sequence is $A-(iii), B-(iv), C-(i), D-(ii)$.

(B) The correct answer is $B$.
Membrane-bound organelles include the endoplasmic reticulum,nuclei,lysosomes,Golgi apparatus,and mitochondria.
Ribosomes are non-membrane-bound ribonucleoprotein particles.
Chromosomes are structures composed of $DNA$ and proteins found within the nucleus and are not considered membrane-bound organelles.

(A) The correct matches are as follows:
$1$. $(A)$ Centriole: It forms the basal body of cilia or flagella $(iv)$.
$2$. $(B)$ Chlorophyll: It is present in the thylakoids of chloroplasts $(ii)$.
$3$. $(C)$ Cristae: These are the infoldings of the inner mitochondrial membrane $(i)$.
$4$. $(D)$ Ribozymes: These are catalytic $RNA$ molecules, which are nucleic acids $(iii)$.
Therefore, the correct sequence is $(A)-(iv), (B)-(ii), (C)-(i), (D)-(iii)$.

(A) : Thylakoids are the flattened sac-like membranous structures that are stacked on top of one another to form the grana of plant chloroplasts.
Chlorophyll and other photosynthetic pigments are situated in the thylakoid membranes,which are the site for the light-dependent reactions of photosynthesis.
$B$ is incorrect because centrioles are involved in spindle formation during cell division,not $RNA$ synthesis.
$C$ is incorrect because chloroplast ribosomes are $70S$ and cytoplasmic ribosomes are $80S$.
$D$ is incorrect because lysosomes contain hydrolytic enzymes that are optimally active at an acidic $pH$ (about $5.0$).

(B) The correct answer is $B$.
While each of the membranous organelles is distinct in terms of its structure and function,many of these are considered together as an endomembrane system because their functions are coordinated.
The endomembrane system includes the endoplasmic reticulum $(ER)$,Golgi complex,lysosomes,and vacuoles.
Since the functions of the mitochondria,chloroplasts,and peroxisomes are not coordinated with the above-mentioned components,they are not considered part of the endomembrane system.

(A) Based on the provided diagram:
$A$ points to the Rough Endoplasmic Reticulum $(RER)$,which is studded with ribosomes.
$B$ points to the Smooth Endoplasmic Reticulum $(SER)$,which lacks ribosomes.
$C$ points to the Nucleus,which is the large central organelle.
$D$ points to the Cytoplasm,the fluid surrounding the organelles.
Therefore,the correct matching is:
$A - (v)$ (Rough endoplasmic reticulum)
$B - (iv)$ (Smooth endoplasmic reticulum)
$C - (viii)$ (Nucleus)
$D - (iii)$ (Cytoplasm)
Thus,the correct option is $(A)$.

(A) is the incorrect statement.
$1$. Mitochondria and chloroplasts are semi-autonomous organelles. They contain their own $DNA$,which encodes for $mRNA$,$tRNA$,and $rRNA$.
$2$. Both organelles possess their own ribosomes,allowing them to synthesize some of their own proteins.
$3$. The thylakoid space and thylakoid membrane are specific to chloroplasts,not mitochondria. Mitochondria have an inner membrane folded into cristae,enclosing the matrix.
$4$. Both organelles are double-membrane bound structures,and chloroplasts are typically larger than mitochondria.

(D) The correct answer is $(d)$.
Adult human red blood cells $(RBCs)$ are enucleated,meaning they lack a nucleus and other cell organelles like mitochondria,ribosomes,and Golgi bodies.
The primary advantage of this structural adaptation is that it maximizes the internal space within the cell.
By removing the nucleus and organelles,the cell can accommodate a significantly larger amount of haemoglobin,which is the oxygen-carrying pigment.
This allows for more efficient transport of oxygen throughout the body.

(A) Plasmodesmata are microscopic channels that traverse the cell walls of plant cells and some algal cells,enabling transport and communication between them.
These structures connect the cytoplasm of adjacent cells,forming a continuous cytoplasmic network known as the symplast.
This pathway allows for the movement of water,ions,and various molecules between cells,making it an effective transport pathway in plants.

(D) In the provided diagram of an animal cell:
$1$. The label $X$ points to the outermost boundary of the cell,which is the cell membrane.
$2$. The label $Y$ points to the stack of flattened,membrane-bound sacs known as the Golgi body (or Golgi apparatus).
Therefore,$X$ represents the cell membrane and $Y$ represents the Golgi body.

(C) The process of protein synthesis and packaging follows a specific pathway within the cell:
$1$. Proteins are synthesized on the ribosomes attached to the Rough Endoplasmic Reticulum $(RER)$.
$2$. These proteins are then transported to the Golgi apparatus (Golgi body) via transport vesicles.
$3$. In the Golgi body,these proteins are modified,sorted,and packaged into vesicles.
$4$. Finally,these vesicles may become lysosomes or be secreted out of the cell.
Therefore,the correct sequence is $RER$ - Golgi body - Lysosomes.

(D) Phagocytosis is a process by which a cell engulfs large particles or microorganisms.
$Amoeba$ uses pseudopodia to perform phagocytosis for feeding.
$WBCs$ (White Blood Cells),specifically neutrophils and macrophages,use phagocytosis to engulf and destroy pathogens as part of the immune response.
Therefore,both $Amoeba$ and $WBC$ exhibit phagocytosis.

(D) The correct matching is as follows:
$a$. Pinocytosis is the process of ingestion of liquid materials into the cell,often referred to as 'cell drinking'. Thus,$a-5$.
$b$. Lysosomes contain hydrolytic enzymes that function optimally at an acidic pH. Thus,$b-3$.
$c$. Endoplasmic Reticulum $(ER)$ is often associated with ribosomes (Rough $ER$). Thus,$c-4$.
$d$. Centrioles are present in animal cells and are absent in most plant cells. Thus,$d-1$.
Therefore,the correct sequence is $a-5, b-3, c-4, d-1$.

(D) The correct answer is $D$ (Cytoplasm).
$A$,$B$,and $C$ (Golgi body,Lysosomes,and $ER$) are all membrane-bound cell organelles found within the eukaryotic cell.
$D$ (Cytoplasm) is the jelly-like substance that fills the cell and surrounds these organelles,rather than being an organelle itself.

(C) $1$. Mycoplasma is a type of prokaryotic cell lacking a cell wall $(1-r)$.
$2$. Mesophyll cells are specialized cells found in leaves,which are plant cells $(2-p)$.
$3$. Capsule is a type of glycocalyx layer found in some bacteria $(3-s)$.
$4$. Flagella in bacteria consist of three parts: filament,hook,and basal body $(4-q)$.
Therefore,the correct matching is $1-r, 2-p, 3-s, 4-q$.

(C) Based on the provided diagram of the endomembrane system:
$A$ points to the central organelle,which is the Nucleus $(iii)$.
$B$ points to the Rough Endoplasmic Reticulum $(RER)$ $(v)$.
$C$ points to the Smooth Endoplasmic Reticulum $(SER)$ $(i)$.
$D$ points to the Ribosomes $(ii)$ attached to the $RER$.
$E$ points to the Nuclear pore $(iv)$ on the nuclear envelope.
Therefore,the correct matching is $A-iii, B-v, C-i, D-ii, E-iv$.

(A) The endomembrane system includes organelles whose functions are coordinated,such as the Endoplasmic Reticulum $(ER)$,Golgi complex,lysosomes,and vacuoles.
Ribosomes are not membrane-bound organelles and are not part of the endomembrane system because they are involved in protein synthesis rather than the transport or processing pathways defined by the endomembrane system.

(B) The correct matches are as follows:
$A$. Vacuole: Involved in storage and excretion of waste products $(iii)$.
$B$. Mitochondria: The site of aerobic respiration,specifically the Krebs cycle $(i)$.
$C$. Golgi body: Acts as the site for the synthesis and packaging of glycolipids and glycoproteins $(iv)$.
$D$. Chloroplast: The site of photosynthesis in plant cells $(ii)$.
Therefore,the correct matching is $(A-iii), (B-i), (C-iv), (D-ii)$.

(B) The correct pair is $B$ (Lysosome - Suicidal body).
$1$. Lysosomes contain hydrolytic enzymes (hydrolases) that can digest cellular components,earning them the name 'suicidal bags' or 'suicidal bodies'.
$2$. Fungi do not typically possess contractile vacuoles; these are common in freshwater protists like Amoeba for osmoregulation.
$3$. Mitochondria contain cristae (folds of the inner membrane),not cisternae (which are found in the Golgi apparatus).
$4$. $RER$ (Rough Endoplasmic Reticulum) is primarily involved in protein synthesis,while the synthesis of glycolipids and glycoproteins occurs in the Golgi apparatus.

(A) . Microfilaments are components of the cytoskeleton.
$B$. Microtubules are structural components found in cilia and flagella.
$C$. Intermediate filaments are composed of durable proteins that provide mechanical strength.
$D$. The cell wall in plants is primarily composed of cellulose.
Therefore,the correct matching is $(A-ii), (B-iii), (C-iv), (D-i)$.

(B) The correct statement is that cell division occurs very rapidly in prokaryotic cells $(B)$.
- Option $A$ is incorrect because Schwann reported that cells have a thin outer layer which is today known as the plasma membrane.
- Option $C$ is incorrect because free ribosomes are responsible for protein synthesis,while smooth endoplasmic reticulum $(SER)$ is responsible for lipid synthesis.
- Option $D$ is incorrect because particles that store starch are known as amyloplasts,not phosphate particles.

(A) The correct matches are as follows:
$1$. Microfilaments are composed of the protein $Actin$ $(A-ii)$.
$2$. Microtubules are composed of the protein $Tubulin$ $(B-iii)$.
$3$. Flagella in eukaryotes are associated with the outer compartment or extension of the cell membrane $(C-iv)$.
$4$. The outer layer of bacteria is known as the $Glycocalyx$ $(D-i)$.
Therefore,the correct sequence is $(A-ii), (B-iii), (C-iv), (D-i)$.

(D) $1$. The egg of an ostrich is the largest isolated single cell.
$2$. Mycoplasma are the smallest living cells,measuring about $0.3 \mu m$ in length.
$3$. $A$ Kinetochore is a protein structure on chromatids where spindle fibers attach during cell division; it is not an organelle,and the term 'organelle without membrane' usually refers to structures like ribosomes or centrioles.
$4$. The 'Mantle' is not a standard term for a structure present in the cytoplasmic region of a cell in the context of cell biology. Therefore,option $D$ is the incorrect pair.

(A) The organelles are classified based on the number of membranes they possess:
$1$. Double-membrane bound organelles: Nucleus,Mitochondria,and Chloroplasts.
$2$. Single-membrane bound organelles: Lysosomes,Golgi bodies,Endoplasmic reticulum,and Vacuoles.
$3$. Non-membrane bound organelles: Ribosomes and Centrosomes.
Since the question asks for an organelle with a single membrane,options $A$,$B$,and $D$ are all technically single-membrane bound. However,in many standard biology contexts,Lysosomes are the most classic example of single-membrane organelles. Given the options provided,all $A$,$B$,and $D$ are correct. If this is a single-choice question,Lysosomes are often cited as the primary example.

(A) Chloroplasts and mitochondria are both semi-autonomous organelles found in eukaryotic cells.
$1$. Both contain their own circular $DNA$ and ribosomes,allowing them to synthesize some of their own proteins.
$2$. Both are capable of self-replication through binary fission.
$3$. However,chloroplasts are primarily found in plant cells and some protists (like algae) to perform photosynthesis,whereas they are absent in animal cells. Mitochondria are found in almost all eukaryotic cells,including animal cells.
Therefore,being present in animal cells is not a common feature.

(A) . Cristae are the infoldings of the inner mitochondrial membrane,which increase the surface area for biochemical reactions. Thus,$a-ii$.
$b$. Cisternae are the flattened,disc-shaped sacs found in the Golgi apparatus. Thus,$b-iii$.
$c$. Thylakoids are flattened,sac-like structures present in the stroma of chloroplasts,which are the sites of light-dependent reactions. Thus,$c-i$.
$d$. Kinetochores are disc-shaped protein structures associated with the centromere of a chromosome,where spindle fibers attach during cell division. Thus,$d-iv$.
Therefore,the correct matching is $(a-ii), (b-iii), (c-i), (d-iv)$.

(D) The correct pair is $D$.
$A$ is incorrect because an Ostrich's egg is a single eukaryotic cell,not a prokaryotic cell.
$B$ is incorrect because animal cells lack a cell wall; they only have a cell membrane.
$C$ is incorrect because plant cells typically lack centrioles,which are characteristic of animal cells.
$D$ is correct because a defining feature of eukaryotic cells is the presence of a well-defined nucleus enclosed by a nuclear membrane.

(B) The correct matches are as follows:
$(1)$ Typical bacterial cell size is generally $1-2 \ \mu m$. Thus,$(1-q)$.
$(2)$ Ribosomes are the sites of protein synthesis in the cell. Thus,$(2-p)$.
$(3)$ Nerve cells are characterized as long and branched structures for signal transmission. Thus,$(3-s)$.
$(4)$ Plasmids are small,circular,extrachromosomal $DNA$ molecules in bacteria that often carry genes for antibiotic resistance or other traits,involved in bacterial transformation. Thus,$(4-r)$.
Therefore,the correct sequence is $(1-q), (2-p), (3-s), (4-r)$.

(C) Let us analyze the statements:
$a-$ Erythrocytes of many mammals (like humans) are enucleated at maturity. This is correct.
$b-$ Sieve tube cells of vascular plants lack a nucleus at maturity. This is incorrect.
$c-$ Centrioles are not membrane-bound organelles. This is incorrect.
$d-$ Centrioles consist of triplets of microtubules,not pairs. This is incorrect.
$e-$ The cytoskeleton is composed of microfilaments,intermediate filaments,and microtubules,which are proteinaceous. This is correct.
$f-$ Chloroplasts contain $70S$ ribosomes (prokaryotic type). This is correct.
$g-$ Aleuroplasts store proteins,not pigments. Chloroplasts and chromoplasts are responsible for plant color. This is incorrect.
$h-$ Vacuoles occupy up to $90\%$ of the volume of plant cells,not animal cells. This is incorrect.
Therefore,option $C$ contains two correct statements.

(C) The correct answer is $C$.
Centrioles are cylindrical structures composed of microtubule triplets made of tubulin protein.
They are typically found in animal cells and some lower plant cells (like certain algae and bryophytes),but they are absent in the cells of higher plants (angiosperms and gymnosperms).
Therefore,the statement that centrioles are present in all plants and animals is incorrect.
Ribosomes are composed of $rRNA$ and proteins.
Ribozymes are $RNA$ molecules that possess catalytic activity,thus acting as enzymes.