All Free Biology MCQs with Answers

• A. 40S
• B. 70S
• C. 65S
• D. 60S

Explanation: Smaller ribosomes (705) are present in prokaryotic cell but larger ribosomes (80S) are present in eukaryotic cells

• A. Nucleoplasm
• B. Cell wall
• C. Protoplasm
• D. None of the above

Explanation: The function of the cell membrane is to form a boundary for the cell. Protoplasm is surrounded by the cell membrane.

• A. Cell wall
• B. Cell membrane
• C. Nucleus
• D. Ribosome

Explanation: The cell wall provides extra strength to the cell, but it is not absolutely necessary. Also, it is not present in all the cells, e.g. it is not present in animal cells.

• A. Organelles
• B. Tissues
• C. A system
• D. Both A and B

Explanation: The group of cells that perform the same function is called tissue (OPTION B). Many different tissues combine to form organs, that can perform multiple functions. Different organs combine to form a system. An organelle is a subcellular structure that performs specific functions.

• A. Golgi complex
• B. Lysosomes
• C. Mitochondria
• D. Ribosomes

Explanation: DNA can be found in the mitochondria as they are thought to be primitive bacteria that have infiltrated into the cell.

• A. Rough Endoplasmic Reticulum
• B. Smooth Endoplasmic Reticulum
• C. Liver cells
• D. Lysosome

Explanation: The smooth endoplasmic reticulum is a part of the endoplasmic reticulum which does not possess ribosomes studded on its membrane. It is involved in the detoxification of many poisons and drugs such as lipid soluble drugs, aspirin, insecticides (DDT), petroleum products and pollutants and converting them to safer water-soluble products.

• A. Robert Hooke ... cell wall
• B. Schlelden and Schwann ... cell theory
• C. Robert Brown... nucleus
• D. Watson and Crick ... DNA model
• E. Virchow... Mosaic model of plasma membrane

Explanation: The Fluid Mosaic hypothesis was formulated by Singer and Nicolson in the early 1970s, not by Virchow. All others are correctly paired.

• A. Protection of cytoplasm
• B. Regulating the passage of different molecules
• C. Protein synthesis
• D. Cellular communication
• E. Cellular transportation

Explanation: All of these are functions of the cell membrane except protein synthesis, which is solely the purpose of ribosomes..

• A. Plant cells
• B. Fungal cells
• C. Bacterial cells
• D. Liver cells

Explanation: A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism. No cells in the human body have a cell wall, hence liver cells will not have one either. Plant cell walls are primarily made of cellulose, which is the most abundant macromolecule on Earth. The cell wall is a characteristic structure of fungi and is composed mainly of glucans, chitin, and glycoproteins. The bacterial cell wall consists of peptidoglycan, an essential protective barrier for bacterial cells that encapsulates the cytoplasmic membrane.

• A. Algae
• B. Fungi
• C. Protozoans
• D. Bacteria

Explanation: Eukaryotic cells have mitochondria and chloroplasts as organelles and those organelles additionally have ribosomes 70S. However, eukaryotic cells (algae, fungi, protozoans) have 80S ribosomes in their cytoplasm, while prokaryotic cells just have 70S ribosomes. Hence, Option D is correct.