Cell Organelles Questions in English

(B) The two organelles that contain their own genetic material $(DNA)$ and ribosomes are $Mitochondria$ and $Plastids$. These organelles are considered semi-autonomous because they can synthesize some of their own proteins.

(N/A) Lysosomes contain very powerful hydrolytic enzymes that are capable of breaking down organic matter.
When a cell gets damaged or its metabolic processes are disturbed,lysosomes may burst,and these enzymes digest their own cell.
Because of this self-digesting action,lysosomes are known as the 'suicide bags' of the cell.

(B) Ribosomes are the sites of protein synthesis within the cell. They are small,granular structures found either floating freely in the cytoplasm or attached to the surface of the Rough Endoplasmic Reticulum $(RER)$.

(B) Effect of absence of Golgi apparatus on the life of a cell:
$(i)$ The packaging and dispatching of various proteins to different targets inside and outside the cell will be severely affected.
$(ii)$ Cellular products cannot be stored,modified,or sorted properly.
$(iii)$ The formation of lysosomes will be inhibited. This leads to the accumulation of worn-out and dead cell organelles within the cell,which may eventually cause cell death.

(N/A) The organelle $Mitochondria$ is known as the powerhouse of the cell.
This is because the process of cellular respiration takes place within the mitochondria to generate energy in the form of $ATP$ ($Adenosine$ $Triphosphate$).
This energy is essential for carrying out various chemical activities required for the life of the cell.

(A) The lipids constituting the cell membrane are synthesized in the smooth endoplasmic reticulum $(SER)$.
Membrane proteins are synthesized by the ribosomes attached to the rough endoplasmic reticulum $(RER)$.
These components are then transported to the cell membrane to facilitate membrane biogenesis.

(B) Amoeba obtains its food through a process called phagocytosis (a type of endocytosis).
When food particles come near the Amoeba,it extends its cell membrane to form finger-like projections known as pseudopodia (false feet).
These pseudopodia surround the food particle and fuse together to form a food vacuole.
Inside the food vacuole,complex substances are broken down into simpler ones,which then diffuse into the cytoplasm.

(D) Ribosomes are the sites of protein synthesis in the cell.
Since enzymes are primarily proteinaceous in nature,ribosomes are involved in their synthesis.
However,most hormones are either steroids (lipids) or proteins. While some protein-based hormones are synthesized by ribosomes,many hormones are not. More importantly,starch is a carbohydrate (polysaccharide) synthesized by plastids (like amyloplasts) in plants,not by ribosomes.
Therefore,$(iii)$ and $(iv)$ are not considered primary functions of ribosomes in the context of general cellular biology.

(A) The endoplasmic reticulum $(ER)$ is involved in the synthesis,folding,modification,and transport of proteins and lipids. It does not generate energy. Energy generation in the form of $ATP$ is the primary function of mitochondria,which are known as the powerhouses of the cell.

(C) Step $1$: Identify the membrane structure of the given organelles.
Step $2$: $Mitochondria$ and $Plastids$ are double-membrane bound organelles.
Step $3$: The $Nucleus$ is a double-membrane bound organelle.
Step $4$: $Lysosomes$ are single-membrane bound organelles.
Therefore, the correct option is $C$.

(B) $RER$ (Rough Endoplasmic Reticulum) has ribosomes on its surface,which are responsible for protein synthesis. Since lysosomal enzymes are proteins,they are synthesized by $RER$. Thus,option $b$ is correct.
Option $a$ is incorrect because $RER$ produces proteins and $SER$ (Smooth Endoplasmic Reticulum) produces lipids.
Option $c$ is incorrect because the endoplasmic reticulum is involved in the synthesis of membrane components,not their destruction.
Option $d$ is incorrect because a nucleoid is the undefined nuclear region found in prokaryotes,not in the nucleoplasm of eukaryotic nuclei.

(C) In the liver cells of vertebrates,the $SER$ (Smooth Endoplasmic Reticulum) plays a crucial role in detoxifying many poisons and drugs. The enzymes present in the $SER$ membrane help in the metabolic breakdown of toxic substances,thereby protecting the cell.

(D) The endoplasmic reticulum $(ER)$ is responsible for the synthesis of both proteins and lipids.
Specifically,the Rough Endoplasmic Reticulum $(RER)$ contains ribosomes on its surface and is primarily involved in protein synthesis.
The Smooth Endoplasmic Reticulum $(SER)$ lacks ribosomes and is primarily involved in the synthesis of lipids.
These molecules are then used for membrane biogenesis,which is the process of building the cell membrane.

(B) The $Golgi$ apparatus is the cell organelle responsible for the modification,packaging,and transport of proteins and lipids. It is also involved in the synthesis of complex sugars from simple sugars.

(C) Vacuoles are membrane-bound organelles found in the cytoplasm of plant and animal cells.
They perform various functions such as storage of nutrients,water,and waste products.
In plant cells,they provide turgidity and rigidity by maintaining cell pressure.
Locomotion is not a function of vacuoles; it is typically carried out by specialized structures like cilia,flagella,or pseudopodia.

(B) Camillo Golgi developed a staining technique known as the 'black reaction',which involved the use of silver nitrate.
This technique allowed for the visualization and detailed study of the Golgi apparatus and individual nerve cell structures.

(C) Mitochondria and chloroplasts are semi-autonomous organelles that contain their own $DNA$ and ribosomes. Because they possess their own $DNA$,they have the capability of self-replication,independent of the nuclear $DNA$.

(D) In plant cells,food is synthesized through the process of photosynthesis,which occurs within specialized organelles called chloroplasts. Because they are the sites of food production,chloroplasts are referred to as the kitchen of the cell.

(A) The smooth endoplasmic reticulum $(SER)$ is responsible for the synthesis of lipids,including steroids and phospholipids,within the cell. In contrast,the rough endoplasmic reticulum $(RER)$ is primarily involved in protein synthesis due to the presence of ribosomes on its surface.

(D) Prokaryotic cells lack membrane-bound organelles such as mitochondria,lysosomes,and plastids.
Ribosomes are the only organelles present in prokaryotic cells,which are non-membrane-bound and are responsible for protein synthesis.

(A) Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells. They are composed of ribosomal $RNA$ $(rRNA)$ and proteins. In contrast,organelles like the Golgi apparatus,chloroplasts,and the nucleus are membrane-bound structures.

(C) Lysosomes are membrane-bound cell organelles that contain digestive enzymes. They are formed by the process of packaging in the Golgi apparatus. The enzymes within lysosomes are synthesized by the rough endoplasmic reticulum,transported to the Golgi apparatus for modification and sorting,and then pinched off as vesicles to form lysosomes.

(C) Lysosomes are known as 'suicide-bags' because they contain powerful digestive enzymes. When the cell gets damaged or its metabolism is disturbed,lysosomes may burst,and the released enzymes digest their own cell.

(N/A) non-membranous cell organelle is a structure within the cell that is not enclosed by a lipid bilayer membrane. The most prominent example of a non-membranous organelle is the $Ribosome$. Other examples include the $Centrosome$ and $Cytoskeleton$.

(A) In photoautotrophic bacteria,photosynthesis occurs in specialized structures called chromatophores.
These are small,membrane-bound vesicles or lamellae that are extensions of the plasma membrane.
These structures contain photosynthetic pigments (like bacteriochlorophyll) that trap solar energy to synthesize food.

(N/A) $Chromoplast$: Found in colored parts of plants such as flowers and fruits.
$Chloroplast$: Found in green parts of plants such as leaves.
$Leucoplast$: Found in non-colored parts of plants such as roots,tubers,and seeds.

(A) Endoplasmic reticulum: It acts as a transport system for materials between various regions of the cytoplasm or between the cytoplasm and the nucleus.
$(b)$ Mitochondria: It produces energy in the form of $ATP$ (Adenosine Triphosphate),hence known as the power house.
$(c)$ Golgi body: It is involved in the packaging and dispatching of proteins and lipids synthesized in the cell.
$(d)$ Lysosome: It contains powerful digestive enzymes capable of breaking down all organic material,hence called the digestive bag or suicide bag.
$(e)$ Vacuole: These are storage sacs for solid or liquid contents.
$(f)$ Chloroplast: It contains chlorophyll,which is essential for photosynthesis,thus acting as the kitchen of the cell.
$(g)$ Nucleus: It contains the genetic material $(DNA)$ and regulates all cellular activities,acting as the control room.

(A) Amoeba obtains its food by forming temporary finger-like extensions of the cell surface known as pseudopodia.
These pseudopodia surround the food particle and fuse over it.
This process results in the formation of a food vacuole inside the cell,where complex substances are broken down into simpler ones.
This process of engulfing food by Amoeba is known as endocytosis.

(B) The two organelles in a plant cell that possess their own genetic material $(DNA)$ and ribosomes are mitochondria and plastids.
These organelles are considered semi-autonomous because they can synthesize some of their own proteins and replicate independently of the cell nucleus.

(B) Lysosomes contain powerful digestive enzymes that are capable of breaking down complex organic molecules,worn-out cell organelles,and foreign materials like bacteria or viruses that enter the cell.
By digesting these waste materials and cellular debris,they keep the cell clean.
Because of this cleaning function,lysosomes are commonly referred to as the 'scavengers of the cells' or 'suicide bags'.

(B) The $Nucleus$ is known as the control center of the cell. It contains the genetic material $(DNA)$ which regulates cellular activities such as metabolism, protein synthesis, and cell division by controlling gene expression.

(A) Leucoplasts are colorless plastids primarily found in the roots of plants,where they store nutrients like starch,oils,and proteins.
$(b)$ Chloroplasts are green-colored plastids containing chlorophyll,which are abundant in the leaves of plants to facilitate photosynthesis.
$(c)$ Chromoplasts are colored plastids (containing pigments like carotene and xanthophyll) that provide red,orange,or yellow colors to flowers and fruits.

(D) Plant cells possess large-sized vacuoles for the following reasons:
$1$. They store many important substances,including nutrients,water,and waste products.
$2$. They contain cell sap,which exerts turgor pressure against the cell wall,providing turgidity and structural rigidity to the plant cell.

(N/A) An animal cell is a eukaryotic cell that lacks a cell wall and contains various membrane-bound organelles. Key components include:
$1$. Plasma membrane: The outer boundary of the cell.
$2$. Nucleus: The control center containing genetic material.
$3$. Cytoplasm: The jelly-like substance filling the cell.
$4$. Mitochondria: The powerhouse of the cell.
$5$. Endoplasmic Reticulum (Rough and Smooth): Involved in protein and lipid synthesis.
$6$. Golgi apparatus: Responsible for packaging and modifying proteins.
$7$. Lysosomes: Known as the suicide bags of the cell.
$8$. Ribosomes: Sites of protein synthesis.
$9$. Centrioles: Involved in cell division.

(N/A) The eukaryotic nucleus is a membrane-bound organelle that contains the cell's genetic material. It consists of a nuclear envelope,nucleolus,chromatin,and nuclear pores. $A$ nucleoid,on the other hand,is an irregularly shaped region within a prokaryotic cell that contains all or most of the genetic material.

Nucleus	Nucleoid
$(i)$ Nuclear membrane is present.	$(i)$ Nuclear membrane is absent.
$(ii)$ Nucleolus is present.	$(ii)$ Nucleolus is absent.
$(iii)$ Genetic material is enclosed within the nuclear envelope.	$(iii)$ Genetic material is not contained in any membrane-bound structure.
$(iv)$ Found in eukaryotic cells.	$(iv)$ Found in prokaryotic cells.

(N/A) The ribosomes, which are present in all active cells, are the sites of protein synthesis. Endoplasmic reticulum helps in transporting these proteins to various places. The smooth endoplasmic reticulum helps in the manufacture of fat and lipids, which, along with proteins, help in building the cell membrane, a process known as membrane biogenesis.

Smooth Endoplasmic Reticulum $(SER)$	Rough Endoplasmic Reticulum $(RER)$
$SER$ does not have ribosomal particles on its surface, hence it looks smooth. It helps in the manufacture of lipids and fat molecules.	$RER$ has particles of ribosomes on its surface. Ribosomes are the sites of protein synthesis.

(N/A) Initially,the dry apricots swell due to endosmosis (water enters the cells). When transferred to a sugar solution,they shrink due to exosmosis (water leaves the cells).
$(b)$ The $RBC$ will lose water to the surrounding hypertonic environment through osmosis,causing the cell to shrink (crenation).
$(c)$ The cell will lose its integrity and die,as the plasma membrane is essential for regulating the movement of substances in and out of the cell.
$(d)$ Boiling kills the cells of the Rhoeo leaves. Since the cells are dead,they cannot perform plasmolysis,and therefore,no change will be observed when sugar syrup is added.
$(e)$ The Golgi apparatus is responsible for packaging and modifying proteins and lipids. If it is removed,all vesicle formation,packaging,and secretion processes within the cell will stop.

(N/A) The three parts that differentiate a plant cell from an animal cell are as follows:
$1$. Cell Wall: It is a rigid outer covering present only in plant cells,providing structural support and protection.
$2$. Chloroplast: These are plastids containing chlorophyll,which are responsible for photosynthesis and are absent in animal cells.
$3$. Large Central Vacuole: Plant cells typically contain a large,permanent central vacuole that occupies most of the cell volume,whereas animal cells have either no vacuoles or very small,temporary ones.

(N/A) The organelle responsible for maintaining the turgidity and rigidity of mature plant cells is the $Vacuole$. In plant cells, large central vacuoles occupy up to $90\%$ of the cell volume. The cell sap contained within the vacuole exerts pressure against the cell wall, known as turgor pressure, which provides structural support and rigidity to the plant.

(B) The $Nucleus$ is called the brain of the cell because it contains the genetic material $(DNA)$ and controls all the metabolic activities and cellular functions of the cell.

(A) $(i)$ Papaya contains chromoplasts,which are colored plastids (other than green) that provide yellow,orange,or red pigments to fruits.
$(ii)$ Grass contains chloroplasts,which are green-colored plastids containing chlorophyll,essential for photosynthesis.

(B) The cell organelle that is generally small-sized in animal cells and large in plant cells is the $Vacuole$.
In plant cells, $Vacuoles$ are large, membrane-bound sacs that can occupy up to $90\%$ of the cell volume, providing turgidity and rigidity to the cell.
In animal cells, if present, $Vacuoles$ are either absent or very small in size.

(B) The two primary types of nucleic acids found in a cell are $DNA$ (Deoxyribonucleic acid) and $RNA$ (Ribonucleic acid).
$DNA$ serves as the genetic material that stores hereditary information.
$RNA$ is primarily involved in protein synthesis and gene expression.

(B) Vacuoles are membrane-bound organelles found in the cytoplasm of cells.
In plant cells,they are large and occupy a significant portion of the cell volume,providing turgidity and rigidity to the cell by maintaining internal pressure.
They also serve as storage sacs for various substances,including water,nutrients,and waste products.

(N/A) The two cell organelles that possess a double membrane are the $Chloroplast$ and the $Mitochondria$. These organelles are unique because they contain their own $DNA$ and ribosomes,which supports the endosymbiotic theory.

(B) The cell organelles that lack a membrane are known as non-membrane-bound organelles.
Ribosomes are the primary example of such organelles,as they are composed of $RNA$ and proteins and are not enclosed by any lipid bilayer membrane.
Centrosomes are another example of non-membrane-bound organelles found in animal cells.

(A) The $Lysosome$ is a single membrane-bound cell organelle found in animal cells. It contains powerful digestive enzymes that help in the breakdown of waste materials and foreign substances within the cell.

(B) In the liver cells of vertebrate animals,the smooth endoplasmic reticulum $(SER)$ plays a crucial role in the detoxification of many poisons and drugs.

(A) Mature mammalian $RBCs$ (Red Blood Cells) lack both mitochondria and endoplasmic reticulum.
This adaptation allows them to carry more hemoglobin,thereby increasing their oxygen-carrying capacity.
They rely on anaerobic respiration for their energy requirements.

(B) The mitochondrion is known as the 'powerhouse of the cell' because it is the site of cellular respiration.
During this process,it oxidizes nutrients (food) to release energy.
This energy is stored and released in the form of $Adenosine$ $Triphosphate$ $(ATP)$,which is the energy currency of the cell.