All Free Biology MCQs with Answers

1791. Which of the following is the empirical formula of chlorophyll b?

• A. C55H70O5N4Mg
• B. C55H72O6N4Mg
• C. C55H70O6N4Mg
• D. C55H72O5N4Mg

Explanation: The molecular formula of chlorophyll b is C55H70O6N4Mg, with magnesium held in the porphyrin-like ring and six oxygen atoms present. Students often choose option a, the formula of chlorophyll a, which differs by having one fewer oxygen atom and two more hydrogen atoms.

1792. Which of the statement is not true for compounds like glycoprotein and glycolipids____________?

• A. They are conjugated molecules of carbohydrates
• B. Both have role in the extra cellular matrix of animals and bacterial cell wall
• C. They are components of biological membranes.
• D. Both are produced and secreted by endoplasmic reticulum

Explanation: Glycoproteins and glycolipids are carbohydrate-containing conjugated molecules found in membranes and in important extracellular structures. They are not both produced and secreted by the endoplasmic reticulum: the ER makes many glycoproteins, whereas glycolipid synthesis mainly involves membranes such as the ER and Golgi, and secretion is not performed by the ER itself.

1793. Chlorophyll molecule contrains __________ as central metal ion.

• A. Fe2+
• B. Mg2+
• C. Zn2+
• D. Cu2+

Explanation: Chlorophyll is a magnesium-containing porphyrin pigment, so Mg2+ occupies its central position and helps absorb light energy. Iron is the central metal in haemoglobin, which causes the common confusion with chlorophyll. Therefore Fe2+ is not the metal ion in chlorophyll.

1794. Red to orange pigments are_____________?

• A. Carotenes
• B. Carotenoids
• C. Xanthophylls
• D. Chlorophyll

Explanation: Carotenes are carotenoid pigments that commonly produce red, orange or orange-yellow colours and contain only carbon and hydrogen. Xanthophylls are oxygen-containing carotenoids and are generally yellow, so c is the likely choice when all carotenoid pigments are treated as identical.

1795. Mitochondria second name is _____________?

• A. Chondriosomes
• B. Condriome
• C. Energysome
• D. Mitosome

Explanation: Mitochondria were historically called chondriosomes because they appear as thread-like or granular bodies in the cytoplasm. Chondriome refers collectively to the mitochondrial component of a cell, so students may choose option b when they confuse the organelle with the collective term. The other terms are not standard names for mitochondria.

1796. The arrangement of ________ speaks of the division of labour within cell?

• A. Molecule
• B. Subatomic particles
• C. Atoms
• D. Organelles

Explanation: Organelles are specialized structures within a cell, and their arrangement allows different cellular tasks to be performed by different parts, which is called division of labour. Molecules and atoms are components of cell structures, not the main functional compartments. Students may choose molecules because cellular processes occur through molecular interactions, but the question refers to cell-level organization.

1797. Fungi resemble plants because they lack___________?

• A. Cell wall
• B. Cytoplasm
• C. Centriole
• D. Nucleus

Explanation: Fungi resemble plants in having a rigid cell wall, but both fungi and typical higher plants lack centrioles, which is the feature targeted by the options. Fungi do have cytoplasm and nuclei, so those cannot explain the resemblance. Students may choose cell wall if it were offered, because that is another important similarity, but among these options centriole is the best answer.

1798. Protein factory is___________?

• A. nucleus
• B. ribosome
• C. golgi complex
• D. centriole

Explanation: Ribosomes are the sites of translation, where the amino-acid sequence encoded by messenger RNA is assembled into a protein. The nucleus may be chosen because it contains DNA and controls protein production, but it does not directly join amino acids into proteins.

1799. Organelles are_______________?

• A. Unicellular structures
• B. Multi-cellular structures
• C. Sub-cellular structures
• D. Non-cellular structures

Explanation: Organelles are specialized sub-cellular structures within a cell, such as mitochondria, ribosomes, and endoplasmic reticulum. They perform particular functions but are not complete cells or multicellular structures. The likely alternative is non-cellular structures, due to misunderstanding that organelles are separate from the cell, although they are parts of cells.

1800. Protein factory of cell is ____________?

• A. Lysosome
• B. Mitochondria
• C. Ribosomes
• D. Golgi apparatus

Explanation: Ribosomes are the sites of translation, where the amino-acid sequence of a protein is assembled according to information carried by messenger RNA. Mitochondria produce much of the cell's ATP, lysosomes digest materials and the Golgi apparatus modifies and packages cell products. Students may choose mitochondria because they are called the powerhouse of the cell, but energy production is not protein synthesis.