Cell MCQ Quiz - Objective Question with Answer for Cell - Download Free PDF

The correct answer is Actin

Explanation:

• Flagella are whip-like structures that enable movement in many microorganisms, including bacteria, protozoa, and sperm cells.
• The cytoskeletal protein primarily involved in the structure and function of flagella is Actin.
• Actin is a globular protein that polymerizes to form long filaments, which provide structural support and drive motility.
• In eukaryotic cells, flagella are composed of microtubules arranged in a characteristic "9+2" pattern. Actin filaments, however, play a crucial role in facilitating intracellular transport and regulating the dynamics of associated proteins.
• In prokaryotic cells (like bacteria), flagella are powered by a rotary motor mechanism, although actin-like proteins are still essential for other cellular processes.

Other Options:

• Myosin: Myosin is a motor protein that interacts with actin filaments to generate cellular movement, such as muscle contraction. While myosin is important in eukaryotic cellular processes, it is not the primary cytoskeletal protein of flagella.
• Globulin: Globulin is a class of proteins found in the blood plasma. It is primarily involved in immunity and transport processes within the bloodstream.
• Albumin: Albumin is another protein found in blood plasma, responsible for maintaining osmotic pressure and transporting molecules.

The correct answer is Lipo-protein molecules

Explanation:

• The plasma membrane, also known as the cell membrane, is a biological membrane that separates the interior of all cells from the external environment.
• It plays a vital role in maintaining the structural integrity of the cell, regulating the movement of substances in and out of the cell, and facilitating communication and signaling between cells.
• The plasma membrane is primarily composed of a lipid bilayer interspersed with proteins.

• S. Jonathan Singer and Garth Nicolson proposed the Fluid Mosaic Model in 1972.
• According to this model, the structure of the plasma membrane is a mosaic and is made up of lipids, proteins, cholesterol, and carbohydrates.
• Lipids are present in the form of two layers known as lipid bilayers with protein embedded in it.
• The major constituent of lipids is phospholipids. Each phospholipid is made up of a hydrophilic head and a hydrophobic tail.
• Two types of proteins present in the plasma membrane are peripheral proteins and integral proteins. Integral proteins are deeply embedded in the membrane as compared to the peripheral proteins.
• Cholesterol helps in retaining the fluidity of the membrane.

Other Options:

• Fat molecules: Although lipids, a category of fats, are a critical component of the plasma membrane. The lipids in the membrane are primarily phospholipids, not simple fats.
• Carbohydrate molecules: Carbohydrates are present in the plasma membrane, but they are not the main structural component. They are attached to lipids (glycolipids) or proteins (glycoproteins) and play a role in cell recognition and signaling.
• Protein molecules: Proteins are a significant component of the plasma membrane, but they are not the sole component. They work in conjunction with lipids to form the lipo-protein structure. Proteins serve various functions, such as acting as channels, carriers, receptors, and enzymes.

The correct answer is Mitochondria

Concept:

• Mitochondria are the sites of aerobic respiration.
• The mitochondria are known as the "powerhouses of the cell" because they are responsible for producing energy in the form of ATP (adenosine triphosphate) through the process of cellular respiration.
• Within the mitochondria, the inner membrane is folded into structures called cristae. These folds increase the surface area for biochemical reactions involved in energy production.
• Cristae play a vital role in the electron transport chain and ATP synthesis, which are crucial steps in aerobic respiration.
• The number of mitochondria in a single cell may be up to 50 to 5000.
• The inner lumen of mitochondria contains ribosome phosphate particles and DNA molecules.
• It has the potential to synthesize its own protein and oxidation of carbohydrates and fats are taken place with the help of enzymes in mitochondria.

Other Options:

• Chloroplast: Chloroplasts are the site of photosynthesis in plant cells and do not contain cristae. Instead, they have thylakoid membranes, where the light-dependent reactions of photosynthesis occur.
• Nucleus: The nucleus is the control center of the cell, housing the genetic material (DNA). It is surrounded by a nuclear envelope with nuclear pores for communication and transport.
• Cell Wall: The cell wall is a rigid structure found in plant cells, fungi, and some prokaryotes. It provides structural support and protection.

The correct answer is 2C

Explanation:

•  DNA content is measured in units called "C," where "C" refers to the amount of nuclear DNA in a haploid cell (e.g., a gamete).
• During the cell cycle, the DNA content changes as the cell progresses through different stages, such as interphase, mitosis, and cytokinesis.
• Metaphase is a stage of mitosis where chromosomes are fully condensed and aligned at the metaphase plate, preparing for segregation into daughter cells.
• During metaphase, the cell is in the mitotic phase where chromosomes are duplicated and consist of two sister chromatids joined at the centromere.
• Each chromosome contains twice the amount of DNA compared to a haploid cell (1C), making the total DNA content 2C.
• This oc curs because DNA replication in the S phase of interphase has already taken place, doubling the DNA content in preparation for division.

The correct answer is Peroxisome

Explanation:

• Cell organelles are specialized subunits within a cell that perform specific functions necessary for cellular processes.
• The peroxisome is a membrane-bound organelle found in eukaryotic cells, primarily involved in oxidative metabolism.
• Catalase is an enzyme that plays a critical role in breaking down hydrogen peroxide (H₂O₂) into water and oxygen, thus protecting cells from oxidative damage caused by reactive oxygen species (ROS).

​Peroxisome:

• Peroxisomes are small, spherical organelles found in the cytoplasm of eukaryotic cells.
• They contain oxidase enzymes that produce hydrogen peroxide as a byproduct of various metabolic reactions, such as the breakdown of fatty acids through β-oxidation.
• The catalase enzyme, present in peroxisomes, detoxifies hydrogen peroxide by converting it into water and oxygen, preventing cellular damage.
• This organelle plays a significant role in lipid metabolism, detoxification of harmful substances, and maintaining redox balance in the cell.

Other Options (Incorrect):

• Spherosome: Spherosomes are single-membrane-bound organelles found in plant cells. They are involved in the storage and synthesis of lipids 
• Glyoxysome: Glyoxysomes are specialized peroxisomes found in plant cells, particularly in germinating seeds. They are involved in the glyoxylate cycle, which converts stored lipids into carbohydrates for energy during germination
• Lysosome: Lysosomes are membrane-bound organelles that contain hydrolytic enzymes responsible for breaking down cellular waste and macromolecules. They play a role in autophagy and recycling cellular components.

The correct answer is i - b, ii - a, iii - c, iv - d

Key Points

• The cell physically expands, duplicates organelles, and creates the molecular building blocks it will require in subsequent stages during G1phase, also known as the first gap phase.
• The cell creates a full copy of the DNA in its nucleus during the S phase. Moreover, it makes duplicates of the centrosome, a structure that organises microtubules. During M phase, the centrosomes aid in the separation of DNA.
• The second gap phase, also known as the G2 phase, is a time of increased cell growth, protein and organelle production, and content reorganisation in preparation for mitosis.
• The cell's nuclear DNA condenses into its visible chromosomes during mitosis and is separated by the mitotic spindle, a specialised microtubule-based structure.

Additional Information

•  Stages of the cell cycle
  • ​A cell must grow, replicate its genetic material (DNA), and physically split into two daughter cells before it may divide.
  • The cell cycle is a structured, predictable series of actions that cells take to complete these goals.
  • Because the two daughter cells can restart the entire process from the beginning after each cycle, the cell cycle is a cycle rather than a linear pathway.

The correct answer is Nucleoid.

Key Points

• In prokaryotic organisms, the nuclear region is not surrounded by any membrane.
  • The undefined nuclear region lacking a nuclear membrane and containing only DNA without proteins in bacteria is called the nucleoid.
• Prokaryotic cells are primitive organisms.
  • In prokaryotes, the nucleoid contains all or most of the genetic material.
  • In prokaryotic cells, the nucleus is not well-defined because it is not surrounded by the nuclear membrane.

Additional Information

• A nucleosome is a section of DNA wrapped around a core of protein.
  • Inside the nucleus, DNA forms a complex with a protein called chromatin, which allows the DNA to condense into small amounts.
• A nucleus, as it relates to genomics, is a membrane-bound organelle within a cell that contains chromosomes.
  • A series of pores, or pores, in the nuclear membrane allow selective passage of certain molecules (such as proteins and nucleic acids) in and out of the nucleus.
• Nucleoproteins are a type of proteins that are associated with nucleic acids and ribosomes and lipoproteins, they often serve as lipid transport and storage proteins such as vitelline.
  • A nucleoprotein is a conjugated protein structure consisting of a protein linked to a nucleic acid, either DNA abbreviated as deoxyribonucleic acid or RNA abbreviated as ribonucleic acid.

Concept:

• Cells are the structural and functional unit of life.
• They exist in different shapes and sizes.
• The structure of a cell is directly proportional to its function.

Explanation:

• A cytoskeleton is found in the cytoplasm as a network of protein filaments.
• There are three types of cytoskeletons found in the cytoplasm- microtubules, microfilaments, and intermediate filaments.
• They are found only in eukaryotic cells.
• Cytoskeleton provides mechanical support to the cell and helps maintain the shape of the cell.
• They are important for cell division and movements inside the cell.
• They also function in supporting the cell organelle and allow cell motility.
• Intracellular transport is not carried out by the cytoskeleton.
• There are vesicles and certain motor proteins that help in intracellular transport.

So, the correct answer is option  i.e. Intracellular transport

Additional Information

•  Microtubules, Microfilaments, and intermediate filaments are proteinaceous structures to support the extensive system of membranes that collectively form the cytoskeleton of a cell.
• The microtubules occur in cilia, flagella, centrioles and basal bodies, mitotic apparatus, etc.
• The microfilaments are mainly composed of the globular protein actin but have filamentous protein myosin also.
• Microfilaments are involved in cytoplasmic streaming and amoeboid movements. 

The correct answer is golgi apparatus

Key Points

Golgi Bodies Functions:

• Its main function is the packaging and secretion of proteins.
• It receives proteins from Endoplasmic Reticulum. It packages it into membrane-bound vesicles, which are then transported to various destinations, such as lysosomes, plasma membrane or secretion.
• They also take part in the transport of lipids and the formation of lysosomes.
• Post-translational modification and enzymatic processing occur near the membrane surface in Golgi bodies, e.g. phosphorylation, glycosylation, etc.
• Golgi apparatus is the site for the synthesis of various glycolipids, sphingomyelin, etc.
• In the plant cells, complex polysaccharides of the cell wall are synthesised in the Golgi apparatus.

Additional Information

Golgi Apparatus:

• The Golgi apparatus has multiple names such as the Golgi complex or Golgi body.
• The name is given on the name of the scientist, who discovered the organelle, i.e. Camillo Golgi.
• It is found in all the eukaryotic cells, plants as well as animals.
• They are membrane-bound organelles present in the cytosol of the cell.
• The Golgi body comprises 5 to 8 cup-shaped, series of compartments known as cisternae. Cisternae is a flattened, disk-shaped, stacked pouches that make up the Golgi apparatus. A Golgi stack mostly contains 4 to 8 cisternae. However, ~60 cisternae are found in some protists. A mammalian cell contains ~40 to 100 stacks of cisternae.
• Animal cells generally contain around 10 to 20 Golgi stacks per cell, which are connected by tubular connections.
• Golgi complex is mostly found near the nucleus.

The correct answer is Cell wall.Key Points

• The cell wall is a rigid layer that surrounds the cell membrane of plant cells, bacteria, fungi, and some protists.
• It provides structural support and protection to the cell, and helps maintain its shape.
• The cell wall is made up of cellulose, a complex carbohydrate that gives it its strength and rigidity.
• The cell wall also has pores that allow for the exchange of water, nutrients, and gases between the cell and its environment.

Additional Information

• The cell membrane is a thin, flexible layer that surrounds the cell and separates its internal environment from the external environment.
  • It regulates the movement of substances in and out of the cell, and also plays a role in cell signaling and communication.
• Lysosomes are membrane-bound organelles that contain enzymes for breaking down and recycling cellular waste and foreign materials.
  • They are found in animal cells, but not in plant cells.
• The Golgi apparatus is an organelle that sorts, modifies, and packages proteins and lipids for transport within the cell or secretion outside the cell.
  • It is made up of a series of flattened, membrane-bound sacs called cisternae.

The correct answer is room.

Key Points

The word "cell" comes from the Latin word "cella", which means a small room or chamber.

• It was first discovered in the year 1665 by the English philosopher and architect named Robert Hooke.
• Later in the year 1839, two German Scientists, Matthias Schleiden and Theodor Schwann proposed the cell theory. According to this theory:
  • Every living organism is composed of one or more cells.
  • The cell is the fundamental unit of life.
  • Cells are the structural and functional organization in organisms.
  • All cells arise from pre-existing cells.
  • All biochemical processes are carried out by cells.
  • On the whole, cell biology is essential to all other biological sciences, including genetics, molecular biology, immunology, etc.

Additional Information

• Cell biology is about the cell, cell division and its functions. Every living species are composed of a cell. The human body comprises around a billion to trillion cells, which are mainly involved in different specialized functions. Their shape and size usually vary, and a single, minute cell alone can perform several functions to keep an organism healthy and alive.
• Cell or cellular biology, the sub-discipline of biology, mainly deals with the study of the cell, cell theory, different types of cell- unicellular, multicellular, cell organelles along with their functions, prokaryotes, eukaryotes, and different kinds of cellular processes.

Concept-

• Mitotic produced genetically identical cells, which are similar to the mother cells.
• Mitotic is also called equational division.
• Mitotic cell division is divided into the following four stages-
  • (a) Prophase  (b) Metaphase  (c) Anaphase  (d) Telophase

Explanation-

• At the beginning of the final stage of mitosis, i.e., telophase, the chromosomes that have reached their respective poles decondense and lose their individuality.
• The individual chromosomes can no longer be seen and chromatin material tends to collect in a mass in the two poles.
• This is the stage which shows the following key events-
  • Chromosomes cluster at opposite spindle poles and their identity is lost as discrete elements.

Hence in telophase, chromosome lost their identity.

Additional Information

• Mitosis or the equational division is usually restricted to the diploid cells only.
• Mitosis usually results in the production of diploid daughter cells with identical genetic complement.
• The growth of multicellular organisms is due to mitosis.
• A very significant contribution to mitosis is cell repair.

The correct answer is Golgi Apparatus.

Key Points

• Golgi Apparatus:
  • The Golgi apparatus has multiple names such as the Golgi complex or Golgi body.
  • The name is given on the name of the scientist, who discovered the organelle, i.e. Camillo Golgi.
  • It is found in all eukaryotic cells, plants as well as animals.
  • They are membrane-bound organelles present in the cytosol of the cell.
  • The Golgi body comprises 5 to 8-cup-shaped, series of compartments known as cisternae. Cisternae is a flattened, disk-shaped, stacked pouches that make up the Golgi apparatus. A Golgi stack mostly contains 4 to 8 cisternae. However, ~60 cisternae are found in some protists. A mammalian cell contains ~40 to 100 stacks of cisternae.
  • Animal cells generally contain around 10 to 20 Golgi stacks per cell, which are connected by tubular connections.
  • The Golgi complex is mostly found near the nucleus.

Additional Information

• Mitochondria.
  • The number of mitochondria in a single cell may be up to 50 to 5000.
  • The inner lumen of mitochondria contains ribosome phosphate particles and DNA molecules.
  • It has the potential to synthesize its own protein and oxidation of carbohydrates and fats are taken place with the help of enzymes in mitochondria.
  • This energy is stored in the form of ATP ( Adenosine Triphosphate ) so, these are known as the "Powerhouse of the cell".​
• Chloroplast:
  • The chloroplast is a double membrane-bound cell organelle.
  • Out of the two membranes, the inner membrane is relatively less permeable. (the outer membrane contains porins).
  • The space limited by the inner membrane is called the stroma.
  • Chloroplasts contain chlorophyll and carotenoid pigments which are responsible for trapping of light energy essential for photosynthesis.
  • The majority of chloroplasts are found in the mesophyll cells of the leaves.

• Chromosomes
  • 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).
  • Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.

Concept:

• Cell cycle refers to the series of changes that occur in a newly formed cell. It involves a cell's growth and division to form two daughter cells.

• The cell cycle comprises two stages - the Interphase and M phase.
• The M Phase represents the phase when the actual cell division or mitosis occurs. It is a short dividing phase.
• Interphase represents the phase between two successive M phases. It is a long non-dividing growing phase.
• Interphase can be divided into 4 steps: Gap 1 (G1), S (synthesis) phase, and Gap 2 (G2).

Important Points

• G₁ Phase - 
  • In a human cell, the G1  phase of the cell cycle lasts for approximately 11-12 hours.
  • During the G1 phase, the cell is metabolically active and continuously grows but does not replicate its DNA.
• S Phase - 
  • In a human cell, the S phase of the cell cycle lasts for about 8 hours.
  • S or synthesis phase marks the period during which DNA synthesis or replication takes place.
• G₂ Phase - 
  • The G2  phase of the cell cycle lasts for about 4 hours.
  • During the G2 phase, proteins are synthesized in preparation for mitosis while cell growth continues. 
• M Phase
  • The M phase of the cell cycle lasts for about 1 hour in a human cell.
  • It is the phase of the cell cycle where cell division takes place.
• The​ cell cycle in a human cell comprising of the Interphase and M phase lasts for a total time of 24 hours.

So the correct answer is option 1 (24 hours).