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

The correct answer is Cytoplasm.

Key Points

• Cytoplasm
  • Cytoplasm is the jelly - like substance present inside the cell.
  • It is jelly - like, because of its semi permeable characteristic.
  • It exists within the cell membrane.
  • Cytoplasm is extranuclear that means it does not exist within the cell’s nucleus.

Additional Information

• Cell wall
  • The cell wall is the outer covering of a cell.
  • It surrounds the plasma membrane of plant cells and provides tensile strength and protection against mechanical and osmotic stress.
  • The cell wall is present in plant cells and absent in animal cells.
• ​Plasma membrane
  • Plasma membrane, also called the cell membrane is mainly composed of lipids and proteins.
  • The major lipids are arranged in a bilayer and called as phospholipids.
  • Plasma membrane also contains cholesterol.
  • Cell membranes also possess protein and carbohydrate as per Biochemical investigation.
  • The ratio of lipid and protein varies in different cell types.
    • For example, in human beings, the membrane of the erythrocyte has approx 40 per cent lipids and 52 per cent protein.
• Plasma
  • Plasma is the largest component of blood, comprising about 55% of its overall content.
  •  Along with water, plasma carries salts, hormones and enzymes.
  • The main purpose of plasma is to transport nutrients, hormones, and proteins to the parts of the body that need them.
  • Plasma is the largest part of the blood. It makes up more than half (about 55%) of its total content. When separated from the rest of the blood, plasma is a pale yellow liquid that contains water, salts, and enzymes.

The correct answer is Ribosome.Key Points

• Living organisms are made up of several cells.
• Cells are the basic functional unit of a body that is capable of independent reproduction.
• A cell can be either a prokaryotic cell or a eukaryotic cell.
• Prokaryotic cell lacks well-defined nuclear membrane-bound nucleus and organelles.
  • A bacterial cell is a prokaryotic cell.
• A eukaryotic cell has a well-defined nucleus and membrane-bound cell organelles.
  • Humans have eukaryotic cells.
• Thus Ribosome is found both in eukaryotic and prokaryotic cells.
• Cell organelles are sub-cellular structures that have characteristic morphological forms and specific functions.
• Mitochondria, ribosomes, plastids, ER, Golgi body, etc. are some examples of cell organelles.

Additional Information

• Nucleus 
  • ​The nucleus is a prominent organelle in a cell. 
  • It is surrounded by a double-layered membrane called the nuclear envelope. 
  • The nuclear envelope separates the nucleus from the cytoplasm. 
  • The nucleus contains chromosomes, which are made up of DNA. 
  • The nucleus is filled with a semi-solid substance called nucleoplasm. 
• Cell organelle
  • ​A cell organelle is a subcellular structure that performs a specific function in a cell.
  • Organelles are similar to organs in the body. 
• Cell membrane
  • ​The cell membrane, also known as the plasma membrane, is a semipermeable barrier that separates the inside of a cell from its outside environment.
  • It's made of a lipid bilayer, which is a double layer of phospholipids.
  • The cell membrane is responsible for regulating what enters and exits the cell. 

• Cell theory is a fundamental principle in biology that explains the properties and functions of cells, the basic unit of life.
• Matthias Schleiden, a German botanist, and Theodor Schwann, a German physiologist, are credited with formulating the cell theory in 1839. Their work established that all living organisms are composed of cells and that the cell is the basic unit of life.
• The key points of the cell theory are:
  • All living organisms are made up of one or more cells.
  • The cell is the basic structural and functional unit of life.
  • All cells arise from pre-existing cells through cell division.

• Rationale: Singer and Nicolson are known for proposing the fluid mosaic model of the cell membrane in 1972. This model describes the cell membrane as a flexible layer made up of lipid molecules with large protein molecules that act as channels through which other molecules enter and leave the cell.

• Rationale: Rudolf Virchow, a German physician, contributed to the cell theory by adding the concept of "Omnis cellula e cellula," which means "All cells come from pre-existing cells." His work emphasized that diseases are caused by changes at the cellular level.

• Rationale: Robertson is known for his work on the unit membrane model, which proposed that the cell membrane is a bilayer of lipids with proteins on the surface. However, he did not contribute to the formulation of the cell theory.

• Among the given options, Schleiden and Schwann are correctly credited with the formulation of the cell theory, which is a cornerstone of modern biology. Their contributions laid the foundation for our understanding of the structure and function of cells in all living organisms.

The correct answer is Cytokinesis.

Additional Information

• The correct option is "Cytokinesis".
• Cytokinesis is the process by which the cytoplasm of a eukaryotic cell divides into two daughter cells after mitosis or meiosis.
•  During cytokinesis, a contractile ring made of actin and myosin filaments forms around the cell, which then contracts and divides the cytoplasm into two parts.
•  In animal cells, cytokinesis results in the formation of a cleavage furrow, while in plant cells, a cell plate forms in the middle of the cell and grows outward until it reaches the cell wall.
• Cytokinesis is a crucial step in cell division, as it ensures that each daughter cell receives a complete set of chromosomes and other cellular components necessary for survival.

 Additional Information

• Sepsis is a potentially life-threatening condition caused by the body's response to an infection. It has no relation to cytokinesis.
• Karyokinesis is the division of the nucleus of a eukaryotic cell into two daughter nuclei during cell division. It is different from cytokinesis, which involves the division of the cytoplasm.
• Genesis refers to the beginning or origin of something and has no relation to cell division or cytokinesis.

The correct answer is Ribosome.Key Points

• Living organisms are made up of several cells.
• Cells are the basic functional unit of a body that is capable of independent reproduction.
• A cell can be either a prokaryotic cell or a eukaryotic cell.
• Prokaryotic cell lacks well-defined nuclear membrane-bound nucleus and organelles.
  • A bacterial cell is a prokaryotic cell.
• A eukaryotic cell has a well-defined nucleus and membrane-bound cell organelles.
  • Humans have eukaryotic cells.
• Thus Ribosome is found both in eukaryotic and prokaryotic cells.
• Cell organelles are sub-cellular structures that have characteristic morphological forms and specific functions.
• Mitochondria, ribosomes, plastids, ER, Golgi body, etc. are some examples of cell organelles.

Additional Information

• Nucleus 
  • ​The nucleus is a prominent organelle in a cell. 
  • It is surrounded by a double-layered membrane called the nuclear envelope. 
  • The nuclear envelope separates the nucleus from the cytoplasm. 
  • The nucleus contains chromosomes, which are made up of DNA. 
  • The nucleus is filled with a semi-solid substance called nucleoplasm. 
• Cell organelle
  • ​A cell organelle is a subcellular structure that performs a specific function in a cell.
  • Organelles are similar to organs in the body. 
• Cell membrane
  • ​The cell membrane, also known as the plasma membrane, is a semipermeable barrier that separates the inside of a cell from its outside environment.
  • It's made of a lipid bilayer, which is a double layer of phospholipids.
  • The cell membrane is responsible for regulating what enters and exits the cell. 

The correct answer is Protein synthesis.

Key Points

• Ribosomes are membranous granular structures present in the cytoplasm.
• They were first observed under an electron microscope as dense particles by George Palade in the year 1953.
• Ribosomes are the site for ''protein synthesis'' so they are also called the ''protein factory'' of the cell.
• There are two types of ribosomes

1. Eukaryotic ribosomes - 80s - occurs in the cytoplasm of eukaryotic cell
2. Prokaryotic ribosomes - 70s - occur in the cytoplasm as well as are associated with the cell membrane of prokaryotic cell.

• The subunits of the ribosomes are:
  • 80s ribosomes - are made of 60s and 40s subunits.
  • 70s ribosomes - are made of 50s and 30s subunits.

Important Points

• Composition of the structure of ribosome:
• They are composed of ribonucleic acid (RNA) and proteins

Additional Information

• Photosynthesis: It is the process by which green plants and some other organisms use sunlight to synthesize nutrients from carbon dioxide and water. In this process, plant the chlorophyll, carbon dioxide, water, sunlight, and release oxygen.
• Synthesis of Fatty acids occurs in the cytoplasm.

The correct answer is Both chloroplast and mitochondria

Concept:

Theory of endosymbiosis:-

• Symbiotic relationship, where one organism lives inside the other, is known as endosymbiosis. 
• The theory proposed that mitochondria and chloroplasts evolved from engulfed prokaryotes.
• A large anaerobic bacteria engulfed an aerobic prokaryote, which then formed an endosymbiotic relationship with the host, gradually developing into a mitochondrion.
• It is believed that chloroplasts originated from a cyanobacterial endosymbiont.

Explanation:

Similarities between Prokaryotic cells, Mitochondria, and Chloroplast:

• Mitochondria and chloroplast are of the same size as prokaryotic cells.
• Mitochondria and prokaryotic cells both have their own circular DNA.
• The ribosome of bacteria, mitochondria, and chloroplasts have a 70S type of ribosome.
• Divides by binary fission.

The correct answer is Cellulose.

• Plant cell walls are primarily made of cellulose.

Key Points

• Cellulose is the most abundant macromolecule on Earth.
  • Cellulose fibers are long, linear polymers of hundreds of glucose molecules.
  • These fibres aggregate into bundles of about 40, which are called microfibrils.

Additional Information

• Carbohydrates are the sugars, starches, and fibres found in fruits, grains, vegetables, and milk products.
  • A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H), and oxygen (O) atoms.
• Lipids are molecules that contain hydrocarbons and make up the building blocks of the structure and function of living cells.
  • A lipid is a biomolecule that is soluble in nonpolar solvents.
• A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid also known as fat molecules in water, as in blood plasma or other extracellular fluids.
  • It consists of a Triglyceride and Cholesterol centre, surrounded by a phospholipid outer shell, with the hydrophilic portions oriented outward towards the surrounding water and lipophilic portions oriented inward toward the lipid centre.

The correct answer is Lysosome.

Key Points

• ​Lysosome:
  • Lysosomes are an important cell organelle found within eukaryotic animal cells.
  • Due to their peculiar function, they are also known as the “suicide bags” of the cell.
  • Lysosomes work as the waste-discarding structures of the cell by processing undesirable materials and degrading them, both from the exterior of the cell and waste constituents inside the cell.
  • But sometimes, the digestive enzymes may end up damaging the lysosomes themselves, and this can cause the cell to die.
  • This is termed autolysis, where “auto” means “self” and “lysis” means “the disintegration of the cell by the destruction of its cell membrane“

Additional Information

• Peroxisomes:
  • It is a microbody.
  • In-plant it helps in photorespiration.
  • In animals concerned with peroxide metabolism.
• Glyoxysomes: These are the special type of peroxisomes found in plants & some fungi.
• Polysome: Many ribosomes may associate with a single mRNA to form multiple copies of a polypeptide simultaneously.
  • Such strings of ribosomes are termed as Polysome.

The correct answer is Cellulose.

• The epidermis is the protective outer layer of clonally related cells covering all plant organs.
• It is made up of cellulose, hemicelluloses, and pectin.

Important Points

• Functions of the cell wall in the plant:
  • Regulates and controls the direction of cell growth.
  • Providing strength, structural support, and maintaining the shape of the cell.
  • It supports the entry of smaller molecules moving freely.

Additional Information

• Cell Membrane is present in all organisms including plants.
  • It is also known as the plasma membrane.
  • It is a semi-permeable membrane composed of lipids and proteins.

Key Points

Explanation:

• Ribosomes are known as protein factories because they are the main site of protein synthesis. The molecule of RNA which is a component of the ribosome organelle is called ribosomal RNA.
• Ribosomes are composed of ribonucleic acids and proteins.
• It is made up of two subunits-
  • Large subunits- join amino acids to form a polypeptide chain.
  • Small subunits- reads RNA.

So, each subunit is made up of one or more of ribosomal RNA and ribosomal proteins.

Explanation:

• The cell is the structural and functional unit of life. 
• The size & shape of cells vary with their functions, for example, Mycoplasmas, the smallest cells, are only 0.3 μm in length while bacteria could be 3 to 5 μm.
• Human red blood cells are about 7.0 μm in diameter
• Osteocytes, the bone cells are the longest-lived cells.
• The largest cell of the Human body is the Female gamete i.e. Ovum, however, according to the options given Neuron will be considered the correct answer. 
• Nerve cells or neurons are the longest body cells

Mistake Points

• The largest body cell in humans is the Female gamete - ovum but here it is not given in the options, so according to the options neurons will be considered correct as it is the longest body cell

The correct answer is Mitochondria and Plastids.

Key Points

• Both mitochondria and chloroplasts contain their own DNA and ribosomes.
• Both plant cells and animal cells possess mitochondria. It has its own DNA and plays a met role in the synthesis of enzymes and the production of energy.
• Mitochondria are membrane-bound cell organelles (mitochondrion, singular) that generate most of the chemical energy needed to power the cell's biochemical reactions.
  • Chemical energy produced by the mitochondria is stored in a small molecule called adenosine triphosphate (ATP).
• Chloroplasts are plant cell organelles that convert light energy into relatively stable chemical energy via the photosynthetic process.
  • By doing so, they sustain life on Earth. Chloroplasts are plant cell organelles that convert light energy into relatively stable chemical energy via the photosynthetic process.

EXPLANATION:

A cell is the fundamental structural and functional unit of all living organisms. Anton van Leeuwenhoek discovered the first living cell in 1674.

• Inside each cell is a dense membrane-bound structure called the nucleus. 
• The nucleus is the largest organelle in the cell that contains thread-like structures called chromosomes on which genes (DNA) are present.
• A gene is the basic physical and functional unit of heredity. Genes are made up of DNA.
• The nucleolus is the round irregular structures present inside the nucleus.
• The ribosome is not a part of the nucleus. They are found floating in the cytosol or attached to the endoplasmic reticulum.

​

The Correct Answer is Option 3 i.e Mitochondria.

• Golgi apparatus:
  • This cell organelle is primarily responsible for storage, processing, and packaging proteins.
  • Golgi Apparatus is found within the cytoplasm of a cell and are present in both plant and animal cells.
• Mitochondria:
  • Mitochondria is the cell organelle also called the Powerhouse of the cell.
  • It generates energy molecules called ATP or Adenosine Triphosphate.
• Cell membrane:
  • The cell membrane, also called the plasma membrane, is found in all cells and separates the interior of the cell from the outside environment.
  • The cell membrane regulates the transport of materials entering and exiting the cell.
• Nucleus:
  • It is a membrane-bound organelle that contains the genetic material of organisms.