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All questions of Cell: The Unit of Life for ACT Exam

Which cell organelle is present in both prokaryotic and eukaryotic cells?
  • a)
    Mitochondria
  • b)
    Endoplasmic reticulum
  • c)
    Nucleus
  • d)
    Ribosomes
Correct answer is option 'D'. Can you explain this answer?

Hansa Sharma answered
  • Prokaryotes and eukaryotes are the two different types of cells. 
  • Eukaryotic cells contain membrane-bound organelles, such as the nucleus, endoplasmic reticulum, mitochondria while prokaryotic cells do not but the ribosome is the only organelle that can be seen in both prokaryotic and eukaryotic cells. 
  • Prokaryotic and eukaryotic ribosomes perform the same functions that is protein synthesis, however, eukaryotic ribosomes are much larger than prokaryotic ones.

 Which of the following is a prokaryote?
  • a)
    Bacteria
  • b)
    Amoeba
  • c)
    Chlamydomonas
  • d)
    Spirogyra
Correct answer is option 'A'. Can you explain this answer?

Hansa Sharma answered
Prokaryotic cells are cells that do not have a true nucleus or most other cell organelles. Organisms that have prokaryotic cells are unicellular and called prokaryotes. Bacteria and archaea are prokaryotes.

The largest subunit of prokaryotic ribosomes is
  • a)
    40S
  • b)
    60S
  • c)
    30S
  • d)
    50S
Correct answer is 'D'. Can you explain this answer?

Shreya Gupta answered
50S, roughly equivalent to the 60S ribosomal subunit in eukaryotic cells, is the larger subunit of the 70S ribosome of prokaryotes. The 50S subunit is primarily composed of proteins but also contains single-stranded RNA known as ribosomal RNA (rRNA).

Glycocalyx is associated with ___________
  • a)
    Nucleosome
  • b)
    Nucleus
  • c)
    Plasma membrane
  • d)
    Nucleolus
Correct answer is option 'C'. Can you explain this answer?

Preeti Iyer answered
The glycocalyx is a thick outer covering of the plasma membrane. It is composed of strands of sugars and proteins bound together. The result is a thick, sticky layer that helps cells stay put in environments with lots of physical stress.

Each question consists of two statements, namely, Assertion (A) and Reason (R).
Assertion (A): Prokaryotic cells have no membrane-bound organelles.
Reason (R): The cytoplasm of prokaryotic cells does not show a streaming movement.
For selecting the correct answer, use the following code:
  • a)
    Both assertion and reason are correct and the reason is the correct explanation for assertion
  • b)
    Assertion is correct but the reason is incorrect.
  • c)
    Both assertion and reason are correct but the reason is not the correct explanation for the assertion.
  • d)
    Both assertion and reason are incorrect.
Correct answer is option 'A'. Can you explain this answer?

Explanation:
• Prokaryotic cells, which are found in bacteria and archaea, lack the membrane-bound organelles that are present in eukaryotic cells. These organelles include the nucleus, mitochondria, endoplasmic reticulum, Golgi apparatus, and lysosomes.
• The cytoplasm of prokaryotic cells does not show a streaming movement, which is a characteristic of eukaryotic cells. In eukaryotic cells, the cytoplasmic streaming is driven by motor proteins that move along actin filaments and microtubules.
• The absence of membrane-bound organelles in prokaryotic cells is related to their small size and simpler structure. They are able to carry out all their necessary functions within the cytoplasm without the need for specialized compartments.
• The lack of cytoplasmic streaming in prokaryotic cells is also related to their small size, as diffusion is sufficient for most of their metabolic processes.

Assertion (A): Prokaryotic cells have no membrane-bound organelles.
Reason (R): The cytoplasm of prokaryotic cells does not show a streaming movement.

The correct answer is option 'A'. Both the assertion and reason are correct, and the reason is the correct explanation for the assertion.

Which is common in plant and animal cells
  • a)
    Mitochondria
  • b)
    Plastids
  • c)
    Centrioles
  • d)
    Central vacuoles
Correct answer is option 'A'. Can you explain this answer?

Ashwini Khanna answered
Mitochondria are present in both plant as well as animal cells. Plastids and central vacuoles are present in plant cells and centrioles are present in only animal cells.

The process of movement of few ions or molecules across the membrane against a concentration gradient from lower to higher  concentration, it is called
a) Diffusion
b)Passive transport
c)Active transport
d) Osmosis
Correct answer is option 'C'. Can you explain this answer?

Vijay Bansal answered
Passive transport, also known as passive diffusion, is a process by which an ion or molecule passes through a cell wall via a concentration gradient, or from an area of high concentration to an area of low concentration. It’s like moving from the train to the platform of a subway station, or stepping out of a crowded room. Basically, passive transport gives an ion or molecule “room to breathe.”

Can you explain the answer of this question below:

Organisms which lack mitosis division and use binary fission method for cell division are known as

  • A:

    prokaryotes

  • B:

    eukaryotes

  • C:

    yeast

  • D:

    fungi

The answer is a.

Neha Joshi answered
  • As in prokaryotes, centrioles are absent.
  • Centrioles play an important part in mitosis during spindle fibre formation. so mitosis is not seen in them, thus they use binary fission.

Cell organelles with single membrane is
  • a)
    Lysosomes
  • b)
    Chloroplast
  • c)
    Plastids
  • d)
    Mitochondria
Correct answer is option 'A'. Can you explain this answer?

Ishaan Menon answered
Lysosomes are single membrane structures containing enzymes for digestion of all types of macromolecules.

Can you explain the answer of this question below:

Maximum enzymes are found in:-

  • A:

    Lysosomes

  • B:

    Mitochondria

  • C:

    Nucleus

  • D:

    E.R.

The answer is b.

Navya Sengupta answered
Mitochondria is the site for aerobic respiration in cell and produces energy in the form of ATP. For the formation of energy different pathways like electron transport chain, kreb's cycle are involved and operated by the different enzymes. Thus, the maximum number of enzymes are found in  mitochondria. 

 Nuclear membrane is absent in
  • a)
    Nostoc
  • b)
    Penicillium
     
  • c)
    Volvox
  • d)
    Agaricus
Correct answer is option 'A'. Can you explain this answer?

Rohit Shah answered
Nostoc, genus of blue-green algae with cells arranged in beadlike chains that are grouped together in a gelatinous mass. Ranging from microscopic to walnut-sized, masses of Nostoc may be found on soil and floating in quiet water. Reproduction is by fragmentation. A special thick-walled cell (akinete) has the ability to withstand desiccation for long periods of time. After 70 years of dry storage, the akinete of one species germinates into a filament when moistened. Like most blue-green algae, Nostoc contains two pigments, blue phycocyanin and red phycoerythrin, as well as chlorophyll, and has the ability to fix nitrogen in specialized cells called heterocysts. A terrestrial species has been used as a supplementary food source in Asia.

Which cell organelle secretes zymogen granules :-
a)Lysosomes
b)Smooth E. R.
c)Golgibody
d)Sphaerosomes
Correct answer is option 'B'. Can you explain this answer?

Vijay Bansal answered
The Golgi apparatus is a system of membranous cisternae and vesicles arranged in stacks near the nucleus. Secretory vesicles or granules usually contain specific substances synthesized by cells that are exported to the extracellular medium. They include zymogen granules, mucous droplets, and mast cell granules.

Rough E.R. mainly responsible for:-
  • a)
    Protein synthesis
  • b)
    Cell wall formation
  • c)
    Lipid synthesis
  • d)
    Cholesterol synthesis
Correct answer is option 'A'. Can you explain this answer?

Neha Joshi answered
Rough endoplasmic reticulum carry ribosomes on their surface. The ribosomes present on rough endoplasmic reticulum synthesize secretory proteins. The proteins required for internal use of cell are synthesized on cytoplasmic ribosomes.

The chlorophyll pigment is readily soluble in:-
  • a)
    Water
  • b)
    Acids
  • c)
    Alkalies
  • d)
    Acetone
Correct answer is option 'D'. Can you explain this answer?

Rajesh Gupta answered
The chlorophyll pigment is readily soluble in acetone. Chlorophylls possess a phytyl chain which is bound to a porphyrin ring system. The possession of the phytyl side chain, which is esterified to the carboxyl group of the ring, gives the chlorophylls their lipid character. Moreover, chlorophylls are fat-soluble compounds that can be extracted from water-containing living plant tissue by organic solvents such as acetone, methanol, or ethanol, which can take up water.

Smallest free living organism are
  • a)
    PPLOs
  • b)
    Bacteria
  • c)
    Viroids
  • d)
    Virus
Correct answer is option 'A'. Can you explain this answer?

Rohan Singh answered
Pelagibacter ubique is one of the smallest known free-living bacterium with a length of 0.37-0.89 μm and an average cell diameter of 0.12-0.20 μm. They also have the smallest free-living bacterium genome; 1.8Mbp, 1354 protein genes, 35 RNA genes.

 The prokaryotic cells are characterised by
  • a)
    Presence of a distinct chromosome
  • b)
    Absence of chromatin material
  • c)
    Absence of a nuclear membrane
  • d)
    Presence of a distinct nuclear membrane
Correct answer is option 'C'. Can you explain this answer?

Vijay Bansal answered
Prokaryotes lack an organized nucleus and other membrane-bound organelles. Prokaryotic DNA is found in a central part of the cell called the nucleoid. The cell wall of a prokaryote acts as an extra layer of protection, helps maintain cell shape, and prevents dehydration.prokaryotic cells are those that do not have a membrane-bound nucleus. In fact "pro-karyotic" is Greek for "before nucleus". Besides bacteria, the cyanobacteria (blue-green algae) are a major group of prokaryotes.

Eukaryotic cells are different from prokaryotic cells in having:
  • a)
     
    True nucleus
  • b)
    Mitochondria in mesosome form
  • c)
    Only smooth endoplasmic reticulum
  • d)
    70S ribosomes
Correct answer is option 'A'. Can you explain this answer?

Anjali Iyer answered
Correct option is A)
  • Eukaryotic cells have a true nucleus whereas prokaryotic cells have a primitive nucleus. 
  • The true nucleus of eukaryotes is a double membrane-covered protoplasmic body that contains hereditary information. 
  • A true nucleus is made up of five parts- nuclear envelope, nucleoplasm, nuclear matrix, chromatin, and nucleolus. 
  • The primitive nucleus of a prokaryote is also called as nucleoid as it lacks these parts. It is comprised of only the genetic material. So, option A is correct.

A single unit membrane surrounds the organelle:
  • a)
    Chloroplast
  • b)
    Nucleus
  • c)
    Lysosome
  • d)
    Microsome
Correct answer is option 'C'. Can you explain this answer?

Pooja Mehta answered
Single membrane-bound: Some organelles are bounded by a single membrane. For example, vacuole, lysosome, Golgi Apparatus, Endoplasmic Reticulum etc. They are present only in a eukaryotic cell.

Protoplasm found inside the nucleus is known as
  • a)
    Amyloplast
  • b)
    Nucleoplasm
  • c)
    cytoplasm
  • d)
    Elaioplast
Correct answer is option 'B'. Can you explain this answer?

Nandini Patel answered
Protoplasm is the living content of a cell that is surrounded by a plasma membrane. It is a general term for the cytoplasm. Protoplasm is composed of a mixture of small molecules such as ions, amino acids, monosaccharides and water, and macromolecules such as nucleic acids, proteins, lipids and polysaccharides.Similar to the cytoplasm of a cell, the nucleus contains 'nucleoplasm' (nucleus sap) or karyoplasm. The nucleoplasm is one of the types of protoplasm, and it is enveloped by the nuclear membrane or nuclear envelope. The nucleoplasm includes the chromosomes and nucleoli.

The rod shaped bacteria is called as
  • a)
    Bacillus
  • b)
    Vibrio
  • c)
    Spiral
  • d)
    Spherical
Correct answer is option 'A'. Can you explain this answer?

The shapes of bacteria are bacillus (rod like), coccus (spherical), vibrio (comma shaped) and spirillum (spiral).

The structure of plasma membrane fluid mosaic model is proposed by
  • a)
    Gram
  • b)
    Singer and Nicolson
  • c)
    Schwann and Schleiden
  • d)
    Robert brown
Correct answer is option 'B'. Can you explain this answer?

Rajeev Saxena answered
 An improved model of the structure of cell membrane was proposed by S.J. Singer and G.L. Nicolson (1972) widely accepted as fluid mosaic model.CORRECT OPTION IS B.

Phospholipid synthetase enzyme occur in :-
  • a)
    RER
  • b)
    SER
  • c)
    Golgibody
  • d)
    Glyoxysome
Correct answer is option 'B'. Can you explain this answer?

Pooja Mehta answered
There are two forms of this enzyme; one is found in the outer mitochondrial membrane, while the other is found in the endoplasmic reticulum. ... This occurs primarily in the endoplasmic reticulum. Phosphatidic acid can be used in the synthesis of several phospholipids by two different mechanisms.

Lysosomes are produced by
  • a)
    Leucoplast
  • b)
    Golgi bodies
  • c)
    Mitochondria
  • d)
    Endoplasmic reticulum
Correct answer is option 'B'. Can you explain this answer?

Rohan Unni answered
These are membrane bound vesicular structures formed by the process of packaging in the Golgi apparatus.

Chlorophyll in chloroplasts is located in
  • a)
    Pyrenoid
  • b)
    Both grana and stroma
  • c)
    Grana
  • d)
    Stroma
Correct answer is option 'C'. Can you explain this answer?

Raghav Bansal answered
Correct Answer :- c
Explanation : Chloroplasts are structurally made up of two components- thylakoids (internal membrane structures) and stroma. Some of the thylakoid membranes are stacked one above the other and are called as grana. The grana contain light trapping pigment chlorophyll and are thus the site of light reaction.

Which of the following cell organelles store hydrolytic enzymes?
  • a)
    Chloroplasts
  • b)
    Centrioles
  • c)
    Chromoplasts
  • d)
    Lysosomes
Correct answer is option 'D'. Can you explain this answer?

Lysosomes are spherical bodies, or vacuoles that are enclosed by a single membrane  (membrane- bound organelles). It contains different hydrolytic enzymes, such as proteases, lipases, and nucleases that are capable of breaking down all types of biological polymers (e.g., proteins, nucleic acids, carbohydrates, and lipids) that enter the cell or are no longer useful to the cell. So, the correct answer is 'Lysosome'.

Carbohydrates, the most abundant biomolecules on Earth, are produced by
  • a)
    Viruses, fungi and bacteria
  • b)
    Fungi, algae and green plant cells
  • c)
    Some bacteria, algae and green plant cells
  • d)
    All bacteria, fungi and algae
Correct answer is option 'C'. Can you explain this answer?

Rocky Handsome answered
Carbohydrates are organic compounds synthesized in the chlorophyll containing cells of some bacteria,-algae and green plant cells, during photosynthesis. Certain photoautotrophic bacteria eg. Green sulphur bacteria and purple sulphur bacteria contain pigments like chlorobium chlorophyll and bacteriochlorophyll respectively that helps them in photosynthesis. During photosynthesis carbon dioxide is reduced into carbohydrates by water and oxygen is liberated. so option C ) is correct ( . __ .)

Animal cell do not possess
  • a)
    Centriole
  • b)
    Plamsodesmata
  • c)
    Ribosomes
  • d)
    Plasmalemma
Correct answer is option 'B'. Can you explain this answer?

Prisha Singh answered
Animal cell do not possess plasmodesmata but it contain ribosomes, centriole andplamalemma. Plasmodesmata is the connection between two plant cells.

Which one is present nearest to plasmamembrane?
  • a)
    Secondary wall
  • b)
    Tonoplast
  • c)
    Middle lamella
  • d)
    Primary wall
Correct answer is option 'A'. Can you explain this answer?

Rajesh Datta answered
The cell wall of a young plant cell, the primary wallis capable of growth, which gradually diminishes as the cell matures and the secondary wall is formed on the inner (towards membrane) side of the cell.

Chromatin is made up of :–
  • a)
    Nucleoprotein
  • b)
    Nucleoside
  • c)
    Pentose sugar
  • d)
    Nitrogenous base
Correct answer is option 'A'. Can you explain this answer?

In eukaryotes , there is a set of positively charged , basic proteins called history. Histones are organized to form a unit of eight molecules called Histones octamer. The negativity charged, DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome . Nucleosome constitute the repeating unit of a structure in nucleus called chromatin.

Small particles projecting from the inner membrane and cristae of mitochondria are
  • a)
    Oxysomes
  • b)
    Microsomes
  • c)
    Informosomes
  • d)
    Myeloid bodies
Correct answer is option 'A'. Can you explain this answer?

C.k Singh answered
Oxysomes are the structure present in the inner surface of mitochondra.it is also known as f0-f1particle or Atp synthese.oxysomes play an important role in formation energy for the functioning of the cell.oxysome help in the electron transport i.e oxidation and reduction rxn in respiration.

Cytoskeleton is made of
  • a)
    Phosphoglycerides
  • b)
    Micro tubules
  • c)
    Proteinaceousfilaments
  • d)
    Hemicellulose
Correct answer is option 'C'. Can you explain this answer?

Rajeev Saxena answered
Proteinaceous filaments
The cytoplasm of all eukaryotic cells is crisscrossed by a network of protein fibres that support the shape of the cell and anchor organelles to fixed locations. It is a dynamic system with three types of fibres-actin filaments, microtubule and intermediate filaments.

Mitochondrial DNA is :-
  • a)
    Naked
  • b)
    Circular
  • c)
    Double stranded
  • d)
    All the above
Correct answer is option 'D'. Can you explain this answer?

Vijay Bansal answered
This genetic material is known as mitochondrial DNA or mtDNA. In humans, mitochondrial DNA spans about 16,500 DNA building blocks (base pairs), representing a small fraction of the total DNA in cells. Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function.

Elaioplasts belongs to
  • a)
    Chloroplast
  • b)
    Leucoplast
  • c)
    Amyloplast
  • d)
    Chromoplast
Correct answer is option 'B'. Can you explain this answer?

Arpita Tiwari answered
The leucoplasts are the colourless plastids of varied shapes and sizes with stored nutrients. Leucoplast includes: a) Amyloplasts storing carbohydrates. b) Elaioplastsstoring oils and fats and c) Aleuroplasts storing proteins.

Many cells function properly and divide mitotically even though they do not have
  • a)
    Plasma membrane
  • b)
    Cytoskeleton
  • c)
    Plastids
  • d)
    Mitochondria
Correct answer is option 'C'. Can you explain this answer?

Plastids have no role in mitotic division of a cell. They are only responsible for colors. Eg; Animal cells do not have plastids yet they can divide.

Which one of the following has its own DNA?
  • a)
    Mitochondria
  • b)
    Dictyosome
  • c)
    Lysosome
  • d)
    Peroxisome
Correct answer is option 'A'. Can you explain this answer?

Gaurav Kumar answered
In mitochondria, the inner membrane space is filled with a matrix which contains dense granules  along  with  ribosomes  and mitochondrial DNA. The mitochondrial DNA is circular in nature. There number varies from 2-6. Besides DNA, a mitochondrion has RNA and its ribosomes also. Thus, a complete protein synthesizing machinery is present in mitochondria, which suggests  the semi-autonomous nature of mitochondria. Dictyosome, lysosome and peroxisome do not have their own DNA.

Which ion holds the ribosomal subunits together
  • a)
    Ca+2
  • b)
    Mn+2
  • c)
    Mg+2
  • d)
    Na+
Correct answer is option 'C'. Can you explain this answer?

Hansa Sharma answered
Owing to its abundance and highest charge density among all biological ions, magnesium is most suitable for neutralizing the negative charge density of RNA nucleotide backbone. Ribosomal subunits associate to form complete ribosome in presence of Mg ion.

 Mitochondria are site of respiration first reported by Kingsbury and supported by Hogeboom.Mitochondria are related with the oxidation of :
  • a)
    Carbohydrates
  • b)
    Fats
  • c)
    Proteins
  • d)
    All the above
Correct answer is option 'D'. Can you explain this answer?

Om Desai answered
Mitochondria are eukaryotic cell organelles. Mitochondria synthesize ATP through the process of aerobic respiration. Hence, mitochondria are called powerhouse of the cell. Carbohydrates are the most common fuel used to derive energy in aerobic respiration. When carbohydrates are in short supply, fats and proteins can also be used in aerobic respiration as reduced substrates. Thus, the correct answer is option D.

Enzymes for ETS occur in (mitochondria) :-
  • a)
    Matrix
  • b)
    Outer wall
  • c)
    Inner membrane
  • d)
    Between inner & outer wall
Correct answer is option 'C'. Can you explain this answer?

Rajeev Saxena answered
The inner mitochondrial membrane (IMM) is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space.The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. The numerous invaginations of the membrane are called cristae, separated by crista junctions from the inner boundary membrane juxtaposed to the outer membrane. Cristae significantly increases the total membrane surface area compared to a smooth inner membrane and thereby the available working space.

The inner membrane creates two compartments. The region between the inner and outer membrane, called the inter membrane space which is largely continuous with the cytosol, and the more sequestered space inside the inner membrane, called matrix.

Chlorophyll is located inside
  • a)
    Stroma
  • b)
    Plasma lemma
  • c)
    Chromatophores
  • d)
    Thylakoids
Correct answer is option 'D'. Can you explain this answer?

The chloroplast consists of a number of organised flattened membranous sacs called the thylakoids,Chlorophyll pigments are present in the thylakoids.

The photograph or diagram of metaphasicchromosome arranged in homologous pair according to their length and thickness, position of centromere is called
  • a)
    Karyogram
  • b)
    Chromogram
  • c)
    Idiogram
  • d)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Lavanya Menon answered
Ideogram is a photograph or diagram of metaphases chromosomes of an organism arranged in homologous pair according to their length, thickness and position of centromere, length of arm, shape and other characteristics. The sex chromosomes are usually placed at the end.

The ability of a living somatic nucleated cell to form the complete organism is called
  • a)
    Cellular totipotancy
  • b)
    Morphogenesis
  • c)
    Cell differentiation
  • d)
    Regeneration
Correct answer is option 'A'. Can you explain this answer?

Rajeev Saxena answered
Totipotency is defined in Wikipedia as the ability of a single cell to divide and produce all the differentiated cells in an organism, including extraembryonic tissues. Totipotent cells formed during sexual and asexual reproduction include spores and zygotes.

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