All Free Biology MCQs with Answers

• A. Single, circular, double-stranded molecule not bound by a membrane
• B. Double, circular molecule
• C. Linear, double-stranded molecule
• D. Single, circular, double-stranded and membrane bound

Explanation: Genomic DNA molecules in prokaryotes is single, circular, double-stranded and not bounded by any membrane and it is freely dispersed in…

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Vacuole and lysosome are single membrane-bounded organelles and nucleus and chloroplast are double-membrane bounded organelles.

• A. Primary wall
• B. Secondary wall
• C. Middle lamella
• D. All of these

Explanation: Cellulose is the major component of primary wall.

• A. Centrioles
• B. Spindle fibers
• C. Cell plates
• D. Centromeres

Explanation: Centrioles are absent in the mitotic cells of higher plants, such as gymnosperms and angiosperms.

• A. Modified cell theory means that all living beings are composed of cells capable of reproducing.
• B. Cell theory does not hold good because all living beings (e.g., viruses) do not have cellular organization.
• C. Cell theory means that all living objects consist of cells whether or not they are capable of reproducing.
• D. None of the above

Explanation: The correct answer is Option C. Cell theory fundamentally states that all living organisms are composed of cells, which are regarded as…

• A. Ultra centrifugation
• B. Electron microscope
• C. Light microscope
• D. X-ray crystallography

Explanation: X-ray crystallography is uniquely suited for studying the binding of proteins on regulatory DNA sequences by providing detailed structural…

• A. Numerical aperture
• B. Focal length of objective
• C. Focal length of eyepiece
• D. Tube length

Explanation: The correct answer is Numerical aperture. While the numerical aperture is crucial for determining the resolution and the quality of the…

• A. Ribosomes and rRNA
• B. Only rRNA
• C. Peroxisomes
• D. Several ribosomes held together by a string of mRNA

Explanation: Polyribosomes, also known as polysomes, are clusters of multiple ribosomes attached to a single mRNA molecule.

• A. Chromatography
• B. X-ray diffraction
• C. Differential centrifugation
• D. Auto-radiography

Explanation: The correct answer is differential centrifugation because it utilizes differences in size and density to isolate organelles from a cell…

• A. Maintains cellular homeostasis
• B. Regulates passage of molecules
• C. Prevents from osmotic lysis

Explanation: The correct answer is that the animal cell membrane does not prevent osmotic lysis.

• A. Formation and breakdown of the nuclear envelope
• B. Formation of the centromere
• C. Formation of ribosomes
• D. Organization of spindle fibers during nuclear division

Explanation: The nucleolus is a prominent sub-structure within the nucleus, noted for its lack of a membrane boundary.

• A. Golgi apparatus
• B. Nucleus
• C. Endoplasmic reticulum
• D. Vacuoles

Explanation: The correct answer is that the tonoplast surrounds vacuoles in plant cells.

• A. Centrioles are present in plant cells.
• B. Centrioles are absent in higher plant cells.
• C. Peroxisomes are absent in plant cells.
• D. Mitochondria are absent in plant cells.

Explanation: The correct answer is that centrioles are absent in higher plant cells.

• A. Nucleus, cytoplasm, and cell wall
• B. Chloroplast, cell wall, and mitochondria
• C. Nucleus, cytoplasm, and mitochondria
• D. Vacuole, chloroplast, and ribosomes

Explanation: Both animal and plant cells contain a nucleus, cytoplasm, and mitochondria, which are essential components for cellular function.

• A. Mitochondrial matrix
• B. Inner mitochondrial membrane
• C. Outer mitochondrial membrane
• D. Intermembrane space

Explanation: ATP synthase is located in the inner mitochondrial membrane, where it plays a crucial role in ATP production through a process known as…

• A. Plastids
• B. Mitochondria
• C. Endoplasmic Reticulum (ER)
• D. Nucleus

Explanation: Mitochondria are often referred to as the powerhouse of the cell because they are the sites of aerobic cellular respiration, a process…

• A. Prokaryotic cells are larger than eukaryotic cells
• B. Prokaryotic cells evolved before eukaryotic cells
• C. Eukaryotic cells lack a nucleus, while prokaryotic cells possess one.
• D. Eukaryotic cells are simpler, while prokaryotic cells are more complex

Explanation: The correct answer is that prokaryotic cells evolved before eukaryotic cells.

• A. Xanthophylls
• B. Carotenoids
• C. Chlorophylls
• D. Anthocyanins

Explanation: Anthocyanins are the correct answer as they are water-soluble pigments located in the vacuoles of plant cells, contributing to the red…

• A. Irregular, spherical
• B. Cylindrical, spherical
• C. Elongated, spherical
• D. Ellipsoidal, square

Explanation: The nucleus is primarily spherical in most cells, providing a compact and efficient space for genetic material.

• A. All individuals of the same species
• B. All individuals of different species
• C. Few individuals of the same species
• D. Few individuals of different species

Explanation: The number of chromosomes is a fundamental characteristic of a species and is maintained across generations to ensure genetic stability…