All Free Biology MCQs with Answers

• A. It contains F1 particles.
• B. It is involved in cellular respiration.
• C. It is a self replicating organelle.
• D. Number of mitochondria is constant

Explanation: Number of mitochondria is not constant. The size and number of mitochondria vary and depend on the physiological activity of the cell.

• A. Parasitic activity
• B. Presence of food vacuoles
• C. Hydrolytic or phagocytic activity
• D. Catalytic activity

Explanation: Lysosomes are the organelles present abundantly in animal cells and exhibit phagocytic activity. When a lysosome bursts, the digestive enzymes come outside and start digesting their cells. Hence, they are known as suicidal bags.

• A. Fungal cells
• B. Prokaryotic cells
• C. All eukaryotic cells
• D. None of the above

Explanation: The phragmoplast is the structure that builds a cell wall (called a "cell plate") between daughter cells. It is the characteristic feature found in some of the eukaryotic cells but not all. Therefore opt D is the right choice here.

• A. Tubulin
• B. Actin
• C. Myosin
• D. Chitin

Explanation: Microfilaments are thin molecules that are composed majorly of actin protein subunits. These polymerize to form elongated filaments.

• A. Thylakoid
• B. F1 particles
• C. Granum
• D. Centrosome

Explanation: Chloroplasts are split into 3 parts, the envelope, stroma and thylakoid. The thylakoid is the site of light-dependent photosynthesis reactions.

• A. Digesting food
• B. Storage of energy
• C. Protein packaging
• D. Moving cytoplasm

Explanation: The lysosome is a membrane-bound cell organelle that contains digestive enzymes. Hence, cells that lack lysosomes would have difficulty digesting food.

• A. Chloroplast
• B. Chlorophyll
• C. Chromoplast
• D. Leucoplast

Explanation: Chromoplasts are plastids, heterogeneous organelles responsible for pigment synthesis (storage and synthesis of carotenoid pigments in flowers and fruits).

• A. No membranous boundary
• B. Hereditary center
• C. Site of synthesis for rRNA
• D. Composed of two regions

Explanation: Nucleus is called the hereditary centre.

• A. Structurally and functionally different
• B. Structurally different but functionally similar
• C. Structurally and functionally similar
• D. Structurally similar but functionally different

Explanation: Mitochondria is the double membrane bounded organelle found in eukaryotes.It is the power house of cell. Structure: The inner membrane forms numerous folds (cristae), which extend into the interior (or matrix) of the organelle. Each of these components plays distinct functional roles, with the matrix and inner membrane representing the major working compartments of mitochondria. The outer mitochondrial membrane is described as double phospholipid membrane that surrounds the inter-membrane space, inner membrane, and inner matrix. Functions: The outer membrane is similar to the plasma membrane in structure. It helps in establishing the connection between the inner mitochondrial and the cytoplasm. The inner membrane is the site for ATP synthesis. So, inner and outer membrane of mitochondria are structurally and functionally different.

• A. Endocytosis
• B. Phagocytosis
• C. Exocytosis
• D. Pinocytosis

Explanation: Option C is correct exocytosis here can be referred to as secretion ( material moving out of cell ) all other options signal towards process of intake of substances