Mitochondria, Plastids & Ribosomes — NEET Biology MCQs with Solutions
Free NEET Biology Mitochondria, Plastids & Ribosomes MCQs with step-by-step solutions (72 questions). Part of Cell: The Unit of Life. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Mitochondria, Plastids & Ribosomes · easy · theory
Mitochondria are called the "power houses of the cell" because they:
A. Perform photosynthesis
B. Synthesise proteins for export
C. Produce ATP by aerobic respiration ✓ Correct
D. Store genetic material
Solution: The mitochondrion is the site of aerobic respiration (Krebs cycle + oxidative phosphorylation), producing ATP.
Q2 — Mitochondria, Plastids & Ribosomes · easy · theory
The inner mitochondrial membrane is folded into finger-like ______ to increase surface area:
A. Grana
B. Lamellae
C. Thylakoids
D. Cristae ✓ Correct
Solution: Cristae bear the enzymes/ETC of oxidative phosphorylation; the inner compartment is the matrix.
Q3 — Mitochondria, Plastids & Ribosomes · medium · theory
The green plastids (chloroplasts) contain stacks of thylakoids called ______, embedded in the ______:
A. Nucleoids; cytoplasm
B. Lamellae; cytosol
C. Grana; stroma ✓ Correct
D. Cristae; matrix
Solution: Grana (thylakoid stacks) hold chlorophyll for the light reactions; the stroma carries out the Calvin cycle.
Q4 — Mitochondria, Plastids & Ribosomes · medium · theory
Colourless plastids that store food are ______; among them amyloplasts store ______:
A. Chromoplasts; fat
B. Elaioplasts; starch
C. Chloroplasts; protein
D. Leucoplasts; starch ✓ Correct
Solution: Leucoplasts store nutrients: amyloplasts (starch), elaioplasts (oils), aleuroplasts (proteins).
Q5 — Mitochondria, Plastids & Ribosomes · hard · theory
Mitochondria and chloroplasts are called semi-autonomous organelles because they:
A. Are made only by the Golgi
B. Possess their own circular DNA and 70S ribosomes and divide by fission ✓ Correct
C. Cannot replicate
D. Have no DNA
Solution: Both contain their own DNA and 70S ribosomes and divide independently — supporting the endosymbiotic theory.
Q6 — Mitochondria, Plastids & Ribosomes · hard · theory
The site of protein synthesis within the cell, present in both prokaryotes and eukaryotes, is the:
A. Ribosome (70S or 80S) ✓ Correct
B. Centriole
C. Lysosome
D. Peroxisome
Solution: Ribosomes (rRNA + protein) are the universal protein factories — 70S in prokaryotes/organelles, 80S in the eukaryotic cytosol.
Q7 — Mitochondria, Plastids & Ribosomes · easy · numerical
Which feature is shared by BOTH mitochondria and chloroplasts but NOT by the nucleus?
A. They are absent in plant cells
B. They are the sites of transcription of all cellular mRNA
C. They contain their own circular DNA and 70S ribosomes ✓ Correct
D. They are bounded by a single membrane
Solution: Both mitochondria and chloroplasts have their own double membrane, circular DNA and 70S ribosomes, making them semi-autonomous; the nucleus has linear DNA and no 70S ribosomes.
Q8 — Mitochondria, Plastids & Ribosomes · easy · numerical
The matrix enclosed by the inner mitochondrial membrane contains the enzymes for which process?
A. The citric acid (Krebs) cycle ✓ Correct
B. Glycolysis
C. The light reactions of photosynthesis
D. Translation of nuclear mRNA on 80S ribosomes
Solution: The mitochondrial matrix houses the enzymes of the Krebs cycle; glycolysis occurs in the cytosol and the light reactions occur in chloroplast thylakoids.
Q9 — Mitochondria, Plastids & Ribosomes · easy · numerical
A ribosome sediments as 80S and its two subunits as 60S and 40S. Such ribosomes are characteristic of the:
A. Mitochondrial matrix
B. Cytoplasm of bacterial cells
C. Cytoplasm of eukaryotic cells ✓ Correct
D. Chloroplast stroma
Solution: The 80S ribosome (60S + 40S) is found on the RER and free in the cytoplasm of eukaryotes; prokaryotes and the organelles (mitochondria, chloroplasts) have 70S ribosomes.
Q10 — Mitochondria, Plastids & Ribosomes · medium · numerical
Assertion (A): Mitochondria and chloroplasts are termed semi-autonomous organelles. Reason (R): They synthesise all of their own proteins and are fully independent of nuclear genes.
A. Both A and R are true but R does not explain A
B. A is true but R is false ✓ Correct
C. A is false but R is true
D. Both A and R are true and R correctly explains A
Solution: They are only semi-autonomous: they have their own DNA and 70S ribosomes and make some proteins, but most of their proteins are coded by nuclear genes and imported — so R (full independence) is false.
Q11 — Mitochondria, Plastids & Ribosomes · medium · numerical
A polysome (polyribosome) differs from a single ribosome in that a polysome:
A. Is a ribosome that has permanently lost its smaller subunit
B. Is a ribosome made entirely of protein without any rRNA
C. Is a ribosome bound only to the nuclear envelope
D. Is a group of several ribosomes translating the same mRNA molecule simultaneously ✓ Correct
Solution: Several ribosomes attach to one mRNA and translate it at the same time, forming a polysome/polyribosome, which increases the rate of protein synthesis.
Q12 — Mitochondria, Plastids & Ribosomes · medium · numerical
In a green leaf chloroplast, the stroma (as distinct from the grana) is the site of:
A. Krebs cycle reactions
B. Storage of hydrolytic enzymes for digestion
C. Enzymatic (dark) reactions that synthesise sugars, plus its own circular DNA and ribosomes ✓ Correct
D. The light-trapping reactions that split water
Solution: The stroma holds the enzymes of the dark reactions (carbon fixation) as well as chloroplast DNA and 70S ribosomes; the light reactions occur in the thylakoids of the grana.
Q13 — Mitochondria, Plastids & Ribosomes · medium · numerical
Which comparison between chromoplasts and leucoplasts is correct?
A. Leucoplasts give flowers their red colour while chromoplasts store proteins
B. Chromoplasts store starch while leucoplasts trap light
C. Chromoplasts contain carotenoid pigments giving colour, while leucoplasts are colourless storage plastids ✓ Correct
D. Both are green because they contain chlorophyll
Solution: Chromoplasts have fat-soluble carotenoids (yellow, orange, red), colouring fruits/flowers; leucoplasts are colourless plastids (amyloplasts, elaioplasts, aleuroplasts) that store starch, oils and proteins.
Q14 — Mitochondria, Plastids & Ribosomes · medium
What kind of ribosome is seen in mitochondria?
A. Both 80S and 70S
B. 70S ✓ Correct
C. None of these
D. 80S
Solution: Mitochondria contain their own 70S ribosomes (the prokaryotic type), reflecting their endosymbiotic origin.
Q15 — Mitochondria, Plastids & Ribosomes · medium
How is a new mitochondrion formed from pre-existing ones?
A. Mitosis
B. Conjugation
C. Fission ✓ Correct
D. Budding
Solution: New mitochondria arise only by fission (division) of pre-existing mitochondria.
Q16 — Mitochondria, Plastids & Ribosomes · medium
What kind of ribosome is present in mitochondria?
A. 70S ✓ Correct
B. 60S
C. 80S
D. 40S
Solution: Mitochondria possess 70S ribosomes in their matrix.
Q17 — Mitochondria, Plastids & Ribosomes · medium
The 'power house' of the cell:
A. Possesses cristae which are extensions of its outer membrane
B. Is found in both eukaryotic and prokaryotic cells
C. Is the site of formation of the 'energy currency' (ATP) of the cell ✓ Correct
D. Is bound by a single membrane
Solution: The mitochondrion is the site where ATP, the energy currency of the cell, is formed. It is double-membrane bound, cristae are folds of the inner membrane, and it is found only in eukaryotic cells.
Q18 — Mitochondria, Plastids & Ribosomes · medium
Choose the incorrect statement about mitochondria.
A. Provide colour to the cell ✓ Correct
B. Produce cellular energy in the form of ATP
C. Possess a single circular DNA molecule in their matrix
D. Site of aerobic respiration
Solution: Mitochondria do not provide colour to the cell; colouration is due to plastids (chromoplasts). Mitochondria produce ATP, contain circular DNA, and are the site of aerobic respiration.
Q19 — Mitochondria, Plastids & Ribosomes · hard
The matrix of a mitochondrion possesses all of the following, except:
A. 70S ribosomes
B. Enzymes for the TCA cycle
C. Elementary particles ✓ Correct
D. Double-stranded, circular DNA
Solution: The matrix contains 70S ribosomes, circular dsDNA and TCA cycle enzymes. Elementary particles (F1 particles/oxysomes) are borne on the inner membrane/cristae, not in the matrix.
Q20 — Mitochondria, Plastids & Ribosomes · medium
Which of the following pairs of cell organelles is considered semi-autonomous?
A. Centrosome and ribosome
B. Nucleus and chloroplast
C. Mitochondria and nucleus
D. Chloroplast and mitochondria ✓ Correct
Solution: Chloroplast and mitochondrion are semi-autonomous organelles because they have their own DNA and 70S ribosomes and can synthesise some of their own proteins.
Q21 — Mitochondria, Plastids & Ribosomes · medium
The inner membrane of a mitochondrion projects as many folds into the matrix, called:
A. Oxysome
B. Cristae ✓ Correct
C. Tubules
D. Cisternae
Solution: The infoldings of the inner mitochondrial membrane into the matrix are called cristae; they increase surface area for ATP synthesis.
Q22 — Mitochondria, Plastids & Ribosomes · medium
Double membrane-bound organelle(s) of the cell is/are:
A. Plastids
B. Mitochondria
C. More than one is correct ✓ Correct
D. Ribosome
Solution: Both plastids and mitochondria are double-membrane bound organelles, so more than one option is correct. Ribosomes have no membrane.
Q23 — Mitochondria, Plastids & Ribosomes · medium
Which of the following is called the 'power house' of the cell?
A. Ribosome
B. Plastids
C. Mitochondria ✓ Correct
D. More than one is correct
Solution: Mitochondria are called the power houses of the cell because they generate ATP through aerobic respiration.
Q24 — Mitochondria, Plastids & Ribosomes · medium
Which of the following is present in the mitochondrion of the cell?
A. All of these ✓ Correct
B. Single circular DNA
C. 70S ribosomes
D. Few RNA molecules
Solution: Mitochondria contain a single circular DNA, a few RNA molecules and 70S ribosomes, so all of these are present.
Q25 — Mitochondria, Plastids & Ribosomes · medium
Mitochondria reproduce by:
A. Fission ✓ Correct
B. Fusion
C. Recombination
D. Transformation
Solution: Mitochondria multiply by fission, dividing from pre-existing mitochondria.
Q26 — Mitochondria, Plastids & Ribosomes · medium
Oval, spherical, rod-like or filamentous and colourless plastids, usually found in storage organs not exposed to sunlight, are:
A. More than one is correct
B. Chromoplasts
C. Leucoplasts ✓ Correct
D. Chloroplast
Solution: Leucoplasts are colourless plastids of varied shape found in non-green storage organs; they store food materials.
Q27 — Mitochondria, Plastids & Ribosomes · medium
Protein-storing leucoplasts are known as:
A. Amyloplasts
B. Elaioplasts
C. None of these
D. Aleuroplasts ✓ Correct
Solution: Aleuroplasts (proteinoplasts) are leucoplasts that store proteins. Amyloplasts store starch and elaioplasts store oils/fats.
Q28 — Mitochondria, Plastids & Ribosomes · medium
Which of the following plastids contain carotene and xanthophyll pigments?
A. Leucoplasts
B. More than one is correct
C. Chromoplasts ✓ Correct
D. Chloroplast
Solution: Chromoplasts contain fat-soluble carotenoid pigments such as carotene and xanthophyll, giving yellow, orange and red colours.
Q29 — Mitochondria, Plastids & Ribosomes · medium
The fluid present inside the chloroplast is called:
A. Nucleoplasm
B. Matrix
C. Cytoplasm
D. Stroma ✓ Correct
Solution: The membrane-bound fluid space of the chloroplast enclosing the thylakoids is called the stroma.
Q30 — Mitochondria, Plastids & Ribosomes · medium
The number of grana in each chloroplast is/are:
A. 40-100 ✓ Correct
B. 230
C. 100-140
D. 10-40
Solution: According to NCERT, each chloroplast has about 40 to 100 grana.