Mix Example - THE FUNDAMENTAL UNIT OF LIFE Questions in English

(N/A) $(i)$ The Golgi apparatus is involved in the storage of proteins and enzymes.
$(ii)$ It plays a crucial role in the modification,sorting,and packaging of materials synthesized in the cell.
$(iii)$ It is involved in the synthesis of complex sugars from simple sugars.
$(iv)$ It is responsible for the formation of lysosomes and peroxisomes.

(C) $(i)$ Defence: Lysosomes contain powerful hydrolytic enzymes that help in destroying foreign particles like bacteria and viruses that enter the cell.
$(ii)$ Digestion: They help in the intracellular digestion of food particles by breaking down complex organic molecules into simpler substances.
$(iii)$ Cleansing: They act as a waste disposal system by digesting dead,worn-out cell organelles and damaged cell components,thereby keeping the cell clean.

(N/A) The invention of the microscope by $Antony$ $van$ $Leeuwenhoek$ led to the discovery of the microscopic world.
$(b)$ $Amoeba$ is a single cell that constitutes a whole organism. Such organisms are called unicellular organisms.
$(c)$ Every multicellular organism begins its life as a single cell called the zygote. This zygote is formed by the fusion of male and female gametes during fertilisation. Through repeated cell divisions,this single cell develops into a complex multicellular organism.

(N/A) $(i)$ The fundamental unit of life is the cell.
$(ii)$ The cell was first discovered by Robert Hooke in $1665$.
$(iii)$ Cells are generally observed under a microscope because they are microscopic in size. However, some cells are large enough to be seen with the naked eye, for example, an ostrich egg.

(D) $(i)$ The stain commonly used for onion peel is $Iodine$ solution,and for cheek cells,$Methylene$ $blue$ is typically used. $Safranin$ is also used for plant tissues.
$(ii)$ Stains are necessary because they provide contrast to the transparent or colorless cellular components,making them clearly visible under a microscope.
$(iii)$ No,all organelles do not absorb stain equally. The absorption of stain depends on the chemical composition and density of the specific organelle.

(N/A) The cell sap provides turgidity and rigidity to the cell,which helps in maintaining the cell's shape.
$(b)$ The $SER$ (Smooth Endoplasmic Reticulum) in liver cells plays a crucial role in detoxifying many poisons and drugs.
$(c)$ The ribosomes present on the $RER$ (Rough Endoplasmic Reticulum) are the sites of protein synthesis.

(N/A) The cell contains nuclear material which appears as an entangled mass of thread-like structures called chromatin when the cell is not dividing. During cell division,this chromatin material condenses and organizes into distinct rod-like structures known as chromosomes.
$(b)$ Chloroplasts are specialized green-colored plastids found in plant cells. They contain a green pigment called chlorophyll,which is essential for capturing light energy during photosynthesis.
$(c)$ Genes are the functional segments of $DNA$ molecules. They are located on the $DNA$ strands and act as the hereditary units that control specific traits by coding for the synthesis of specific proteins.

(N/A) Cellulose provides structural strength and helps in maintaining the shape and integrity of the cell.
$(b)$ The deeply folded membranes,known as cristae,increase the surface area for $ATP$ generating chemical reactions,thereby enhancing the efficiency of cellular respiration.
$(c)$ Digestive enzymes in lysosomes help in breaking down complex organic food into simple nutrients,digesting foreign particles like bacteria or viruses,and removing old or worn-out cell organelles through autophagy.

(N/A) The cell organelle present in both prokaryotes and eukaryotes is the $Ribosome$.

$Name \text{ of the organelle}$	$Shape \text{ and } Location$
$Ribosomes$	$Ribosomes$ are small, globular, and granular structures. In eukaryotic cells, they are either attached to the rough endoplasmic reticulum or found freely distributed in the cytoplasm. In prokaryotic cells, they are found freely in the cytoplasm.

(N/A) $(i)$ Proteins and lipids provide structural flexibility and integrity to the plasma membrane.
$(ii)$ The plasma membrane is called selectively permeable because it regulates the entry and exit of specific substances while preventing the movement of others.
$(iii)$ Cellulose provides structural strength and rigidity to the plant cell wall. It also helps in water retention,preventing the desiccation of the cell.
$(iv)$ Plasmolysis is the phenomenon where a living plant cell loses water through osmosis,causing the cell contents to shrink away from the cell wall.
$(v)$ The flexibility of the cell membrane allows the cell to engulf food and other materials from its external environment through a process called endocytosis,which is essential for organisms like $Amoeba$.
$(vi)$ The process is known as diffusion.

(N/A) Diffusion: This is a phenomenon of the spontaneous movement of molecules from a region of higher concentration to a region of lower concentration. This process is faster in the gaseous phase than in liquids and solids. This process leads to a uniform concentration within a cell.
Importance: Substances (molecules,ions) such as $CO_2, O_2, H_2O$,etc.,can move across the plasma membrane by the process of diffusion.
$(b)$ Osmosis: It involves the movement of water molecules (solvent particles) from a region of their higher concentration to a region of lower concentration through a semipermeable membrane.
Importance: It is a purely mechanical diffusion process by which cells absorb water without spending any metabolic energy.

(N/A)

Diffusion	Osmosis
$1$. This process can take place in any medium (solid,liquid,or gas).	$1$. This process occurs only in a liquid medium.
$2$. The molecules undergoing diffusion may be in solid,liquid,or gaseous state.	$2$. Only solvent molecules (usually water) undergo osmosis.
$3$. It can occur without or through a semipermeable membrane.	$3$. It always takes place through a semipermeable membrane.
$4$. This process depends on the kinetic energy of the molecules participating.	$4$. This process involves the movement of solvent molecules from a region of higher water potential to a region of lower water potential.
$5$. It establishes an equilibrium in the concentration of molecules throughout the medium.	$5$. It does not necessarily equalize the concentration of solutes on both sides of the membrane.

(N/A) Osmosis is the spontaneous net movement of water molecules from a region of higher water potential to a region of lower water potential through a selectively permeable membrane,such as the plasma membrane. This is a passive process,meaning it does not require the expenditure of cellular energy.
Examples where osmosis is helpful:
$(i)$ Freshwater organisms like $Amoeba$ and $Paramecium$ maintain their internal water balance through osmosis.
$(ii)$ The movement of water into and out of plant cells occurs primarily due to osmosis.
$(iii)$ Absorption of water from the soil by root hairs is facilitated by osmosis.
$(iv)$ It plays a crucial role in the opening and closing of stomata by regulating the turgor pressure of guard cells.
$(v)$ It is responsible for the seismonastic movements (thigmonasty) in the 'touch-me-not' plant ($Mimosa$ $pudica$).
$(vi)$ This process helps plant cells,tissues,and soft organs like leaves,young shoots,and flowers maintain turgidity and structural integrity.

(N/A) $(i)$ Endocytosis: It is the process of ingestion of material by the cells through the plasma membrane.
$(ii)$ Phagocytosis: It is a common method of feeding in some organisms such as $Amoeba$ and sponges. Biologically, it means "cell eating". The $WBCs$ engulf cell debris and microbes with the help of this process.
$(iii)$ Exocytosis: It is the process by which the plasma membrane removes its contents to the surrounding medium.

(N/A) Plastids are double-membrane-bound organelles present only in plant cells. Like mitochondria, they contain their own $DNA$ and ribosomes, allowing them to synthesize some of their own proteins.

Type of Plastid	Function
$1$. Chloroplast	Contains chlorophyll; involved in photosynthesis to produce food.
$2$. Chromoplast	Contains pigments other than green; imparts attractive colours to flowers and fruits.
$3$. Leucoplast	Colourless plastids; primarily store starch, oils, and protein granules.

(B) The $Golgi$ $apparatus$ is primarily responsible for the packaging,modification,and secretion of proteins and lipids synthesized by the endoplasmic reticulum.
It acts as the 'post office' of the cell,where materials are sorted,packaged into vesicles,and then secreted out of the cell or transported to other organelles.

(C) The $Golgi$ $Apparatus$ is responsible for the synthesis of complex sugars from simple sugars within the cell.
It also plays a key role in the packaging and modification of proteins and lipids.

(D) According to the endosymbiotic theory,certain cell organelles are believed to have originated from independent prokaryotic organisms that were engulfed by a host cell.
These organelles,specifically $Mitochondria$ and $Plastids$ (such as chloroplasts),possess their own circular $DNA$ and $70S$ ribosomes.
Because they contain their own genetic material and protein-synthesizing machinery,they are capable of self-replication and producing some of their own proteins.
Therefore,the correct option is $D$.

(A) Viruses are considered to be at the border of living and non-living organisms. Unlike bacteria,amoebae,or sperm cells,which are cellular organisms,viruses consist of genetic material ($DNA$ or $RNA$) enclosed in a protein coat called a capsid. Because they lack cellular machinery and metabolic processes,they can be crystallized and stored like chemical substances,a property characteristic of non-living matter. Therefore,the correct answer is $A$.

(B) cell swells up when it is placed in a hypotonic solution.
In a hypotonic solution,the concentration of water molecules in the surrounding medium is higher than the concentration of water molecules inside the cell.
Due to the process of osmosis,water molecules move from the region of higher water concentration (outside) to the region of lower water concentration (inside the cell) through the semi-permeable plasma membrane.
This net movement of water into the cell causes it to swell.

(C) Chromosomes are thread-like structures located inside the nucleus of animal and plant cells.
Each chromosome is made of protein and a single molecule of deoxyribonucleic acid $(DNA)$.
These components are essential for the packaging of genetic material within the cell nucleus.

(D) Ribosomes are the sites of protein synthesis in the cell.
$(i)$ Ribosomes synthesize proteins,which is their primary function.
$(ii)$ Enzymes are proteins; therefore,ribosomes are involved in their synthesis.
$(iii)$ Many hormones (peptide hormones) are proteins; therefore,ribosomes are involved in their synthesis.
$(iv)$ Starch is a polysaccharide (carbohydrate),not a protein. Ribosomes do not synthesize starch molecules; starch synthesis occurs in plastids (amyloplasts).
Thus,$(iii)$ and $(iv)$ are not functions of ribosomes in the context of direct synthesis,but specifically,$(iv)$ is definitely not a function. However,since peptide hormones are proteins,$(iii)$ is a function. The question asks for what is $NOT$ a function. Starch synthesis $(iv)$ is definitely not a function. Among the options provided,$(iii)$ and $(iv)$ are often grouped in such questions as non-ribosomal functions,though $(iii)$ is technically a protein. Given the standard curriculum,$(iv)$ is the primary non-function.

(A) Plasmolysis is the process in which cells lose water in a hypertonic solution.
When a plant cell is placed in a hypertonic solution (a solution with a higher solute concentration than the cell sap),water moves out of the cell due to osmosis.
As water leaves the cell,the cytoplasm shrinks away from the cell wall.
This phenomenon is known as plasmolysis.

(B, C) In cell biology,organelles are classified based on their membrane structure:
$1$. Mitochondria and Plastids are double-membrane bound organelles.
$2$. Vacuoles are bound by a single membrane known as the tonoplast.
$3$. Lysosomes are also bound by a single membrane.
Since both $B$ and $C$ are single-membrane bound,in the context of standard multiple-choice questions where only one answer is expected,both are technically correct. However,if this is a single-choice question,usually $B$ or $C$ would be selected. Given the options,both Vacuole and Lysosome are single-membrane organelles.

(D) The correct answer is $D$.
$A$ is true: Mitochondria are known as the powerhouse of the cell because they produce energy in the form of $ATP$ through cellular respiration.
$B$ is true: Mitochondria and plastids are semi-autonomous organelles containing their own $DNA$ and ribosomes,allowing them to synthesize some of their own proteins. The nucleus also contains $DNA$.
$C$ is true: The Golgi apparatus plays a crucial role in packaging and modifying proteins,and it is involved in the formation of lysosomes.
$D$ is false: Protoplasm is the living content of the cell,which includes both the cytoplasm and the nucleus. Cytoplasm is only the jelly-like substance present between the cell membrane and the nucleus.

(D) $Leucoplasts$ are a type of plastid that are primarily responsible for the storage of nutrients.
They are colorless plastids that store materials such as starch, oils, and protein granules.
$Golgi$ apparatus is involved in packaging and secretion.
$Chloroplasts$ are involved in photosynthesis.
$Chromoplasts$ provide color to flowers and fruits.

(A) The functional segments of $DNA$ are known as genes.
Genes are the basic units of heredity and are responsible for the transmission of traits from parents to offspring.
Each gene contains the instructions required to synthesize a specific protein or functional $RNA$ molecule.

(B) The Endoplasmic Reticulum $(ER)$ is a network of membrane-bound tubules and sacs.
Its structure is composed of a lipid bilayer with embedded proteins,which is fundamentally similar to the structure of the plasma membrane.
This similarity is due to the process of membrane biogenesis,where proteins and lipids synthesized by the $ER$ are used to build the plasma membrane and other cell organelles.

(C) Chloroplasts are specialized organelles found in plant cells that perform photosynthesis.
They contain the green pigment chlorophyll,which is essential for trapping light energy.
In addition to chlorophyll,chloroplasts also contain accessory pigments,specifically carotenoids,which include carotenes and xanthophylls.
Carotenes are typically orange in color,while xanthophylls are yellow.
Therefore,besides chlorophyll,chloroplasts contain yellow or orange pigments.

(D) The symbol $\mu$ represents the prefix 'micro'.
By definition,$1 \text{ micro} = 10^{-6}$.
Therefore,$1 \mu m = 10^{-6} \text{ m}$.
This unit is commonly used in biology to measure the size of cells and organelles.

(A) Lysosomes are membrane-bound vesicular structures formed by the process of packaging in the Golgi apparatus.
These vesicles contain hydrolytic enzymes (hydrolases like lipases,proteases,and carbohydrases) that are synthesized in the rough endoplasmic reticulum and then transported to the Golgi apparatus for modification and packaging into lysosomes.

(A) Anton van Leeuwenhoek was the first person to observe and describe living cells,such as bacteria,protozoa,and spermatozoa,using a simple microscope in $1674$.
Robert Hooke discovered dead cells in a cork slice in $1665$.
Purkinje coined the term 'protoplasm'.
Robert Brown discovered the nucleus in the cell.

(B) The correct answer is $B$.
$A$ is correct: Osmosis is the movement of water across a semipermeable membrane,which depends on the solute concentration.
$B$ is incorrect: Plasma membranes in plants are composed of lipids and proteins; they do not contain chitin. Chitin is a structural polysaccharide found in the cell walls of fungi and the exoskeletons of arthropods,not in plant plasma membranes.
$C$ is correct: Biological membranes are primarily composed of a phospholipid bilayer with embedded proteins.
$D$ is correct: Since the membrane is lipid-based,substances that are lipid-soluble (soluble in organic solvents) can diffuse through the membrane easily.

(C) The $Smooth$ $Endoplasmic$ $Reticulum$ $(SER)$ is the cell organelle responsible for the detoxification of many poisons and drugs.
In liver cells of vertebrates,$SER$ plays a crucial role in detoxifying a wide range of toxins and drugs,making them more water-soluble and easier for the body to excrete.

(D) The $Rough$ $Endoplasmic$ $Reticulum$ $(RER)$ is responsible for the synthesis of proteins because it has ribosomes attached to its surface.
$Smooth$ $Endoplasmic$ $Reticulum$ $(SER)$ is responsible for the synthesis of lipids (fats).
These proteins and lipids are essential for building the cell membrane,a process known as membrane biogenesis.
Therefore,the correct answer is $Rough$ $Endoplasmic$ $Reticulum$ (considering the primary site of protein synthesis and the overall role of the $ER$ system).

(A) In prokaryotic cells,the nuclear region is not well-defined because it lacks a nuclear membrane. This undefined nuclear region,which contains only nucleic acids,is called the $Nucleoid$.

(B) The $Golgi$ $apparatus$ is the cell organelle responsible for the modification, packaging, and secretion of proteins and lipids.
One of its primary functions is the synthesis of complex sugars from simple sugars.
It also plays a crucial role in the formation of lysosomes.

(C) Vacuoles are membrane-bound organelles found in the cells of plants,fungi,and some protists,animals,and bacteria.
Their primary functions include:
$1$. Storage: They store nutrients,water,and various substances.
$2$. Turgidity and Rigidity: In plant cells,the large central vacuole maintains turgor pressure,which provides structural support and rigidity to the cell.
$3$. Waste Excretion: They help in the removal of waste products from the cell.
Locomotion is not a function of the vacuole. Locomotion in cells is typically facilitated by structures like cilia,flagella,or pseudopodia.

(D) $Amoeba$ is a unicellular organism that captures its food using temporary finger-like extensions of its cell surface called pseudopodia.
This process of engulfing food particles from the external environment into the cell is known as endocytosis.
Once the food is inside,it is enclosed in a food vacuole where digestion occurs.
Therefore,the correct term for the acquisition of food by $Amoeba$ is endocytosis.

(A) The cell wall of plants,such as $Hydrilla$,$Mango$ $tree$,and $Cactus$,is primarily composed of cellulose,which provides structural support and rigidity.
In contrast,the cell wall of $Bacteria$ is made up of peptidoglycan (also known as murein),which consists of sugars and amino acids.
Therefore,the correct option is $A$.

(B) Plastids are organelles found in plant cells that are classified based on the pigments they contain:
$1$. Chromoplasts: These are coloured plastids (containing pigments like carotenoids) that provide yellow,orange,or red colours to various plant parts.
$2$. Chloroplasts: These are green-coloured plastids containing chlorophyll,which is essential for photosynthesis.
$3$. Leucoplasts: These are colourless plastids primarily involved in the storage of nutrients like starch,oils,and proteins.
Therefore,the sequence for coloured,green,and colourless plastids is Chromoplasts,Chloroplasts,and Leucoplasts respectively.

(C) In a non-dividing cell,the genetic material is present in the form of chromatin material.
Chromatin is a complex of $DNA$ and proteins (histones).
It appears as an entangled mass of thread-like structures within the nucleus.
When the cell prepares to divide,this chromatin condenses into distinct,thick,rod-like structures known as chromosomes.

(D) In $1839$,the Czech physiologist $Jan$ $Evangelista$ $Purkinje$ coined the term $Protoplasm$ for the fluid substance of the cell.
$Protoplasm$ is the living content of the cell,which includes both the cytoplasm and the nucleus.
Therefore,the correct option is $D$.

(A) Camillo Golgi discovered the Golgi apparatus in $1898$. He used a technique called 'black reaction' to stain the nerve cells and other cells. This technique involves the use of silver nitrate solution,which helps in visualizing the structure of the Golgi apparatus under a microscope. Therefore,silver nitrate solution is specifically used to study the Golgi apparatus.

(B) Mitochondria and chloroplasts are unique cell organelles because they possess their own $DNA$ and ribosomes.
This allows them to synthesize some of their own proteins,a phenomenon known as semi-autonomous nature.
Since the nucleus is the primary site of $DNA$ in a cell,mitochondria are the organelles other than the nucleus that contain $DNA$.

(C) The $Chloroplast$ is known as the 'kitchen of the cell'.
This is because chloroplasts contain the green pigment $Chlorophyll$, which is essential for the process of $Photosynthesis$.
Through $Photosynthesis$, plants synthesize their own food (glucose) using sunlight, water, and carbon dioxide, similar to how a kitchen is used to prepare food.

(D) The $Smooth$ $Endoplasmic$ $Reticulum$ $(SER)$ is responsible for the synthesis of lipids, including steroids and phospholipids, which are essential for the formation of the cell membrane.
In contrast, the $Rough$ $Endoplasmic$ $Reticulum$ $(RER)$ is primarily involved in protein synthesis due to the presence of ribosomes on its surface.
Therefore, the correct option is $D$.

(B) The concept that new cells arise from pre-existing cells, known as "Omnis cellula-e cellula", was proposed by Rudolf Virchow in $1855$.
This statement expanded the cell theory originally proposed by Schleiden and Schwann, which did not explain how new cells were formed.
Therefore, the correct answer is $B$ (Virchow).

(B) The cell theory was formulated by $M.J. Schleiden$ and $Theodor Schwann$ in $1838$ and $1839$, respectively.
$M.J. Schleiden$, a German botanist, observed that all plants are composed of different kinds of cells which form the tissues of the plant.
$Theodor Schwann$, a British zoologist, reported that cells had a thin outer layer which is today known as the '$plasma membrane$'.
Together, they proposed the cell theory, which states that all living organisms are composed of cells and products of cells.

(C) Prokaryotic cells are characterized by the absence of membrane-bound organelles such as mitochondria,plastids,and lysosomes.
Ribosomes are the only organelles present in prokaryotic cells.
These ribosomes are of the $70S$ type,which are smaller than the $80S$ ribosomes found in eukaryotic cells.
They are not membrane-bound,which allows them to exist in the cytoplasm of prokaryotes.