All Free Biology MCQs with Answers

• A. Rough endoplasmic reticulum
• B. Smooth endoplasmic reticulum
• C. Golgi complex
• D. Cell membrane

Explanation: In plant cells, the Golgi apparatus consists of a number of isolated units called dictyosomes while in animal cells it occurs as a single compact or loose complex. The dictyosomes are engaged in secretory activities (because secretory materials are produced in dictyosomes) and rapid divisions (because wall materials are synthesized in dictyosomes).

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

Explanation: Protoplast of a cell does not include the cell wall.

• A. Smooth endoplasmic reticulum
• B. Rough endoplasmic reticul•rn
• C. Mitochondria
• D. Cell membrane

Explanation: In eukaryotes, the electron transport chain is located in the inner mitochondrial membrane. In prokaryotes, it is located within the plasma membrane.

• A. Endosmosis
• B. Osmosis
• C. Active transport
• D. Facilitated diffusion

Explanation: The movement of glucose from intestinal fluid into the blood is mostly through facilitated diffusion. Inside intestinal cells, glucose enters actively (with sodium co-transport). But from the intestinal cell to the blood, glucose moves by facilitated diffusion, through carrier proteins (like GLUT2) without using ATP.

• A. Nucleus
• B. Mitochondria
• C. Lysosomes
• D. Chloroplast

Explanation: The correct answer is Lysosomes. Lysosomes are specialized for the breakdown and recycling of cellular waste through enzymatic reactions and do not require DNA for this purpose. In contrast, the nucleus contains the cell's primary genetic material as linear DNA, which is essential for overall cellular control and function. Mitochondria and chloroplasts both contain circular DNA, which is crucial for their specific roles in energy production and photosynthesis, respectively. These organelles are thought to have originated from ancestral prokaryotic cells, which explains their possession of DNA.

• A. Rough Endoplasmic Reticulum (RER)
• B. Smooth Endoplasmic Reticulum (SER)
• C. Golgi Complex
• D. Mitochondria

Explanation: The Golgi complex is a critical organelle in the cell responsible for processing and packaging proteins and lipids. It forms lysosomes by budding off vesicles filled with enzymes that can digest cellular waste and debris. The Rough Endoplasmic Reticulum (RER) primarily deals with protein synthesis, while the Smooth Endoplasmic Reticulum (SER) is focused on lipid production and detoxification. Mitochondria are involved in energy production and do not play a role in lysosome formation.

• A. Mitochondria
• B. Chloroplast
• C. Ribosomes
• D. Both A and B

Explanation: The correct answer is Chloroplast, which is responsible for the process of photosynthesis. In this process, chloroplasts convert light energy into chemical energy, releasing oxygen as a byproduct. Mitochondria, on the other hand, are involved in cellular respiration, where they utilize oxygen to produce energy and release carbon dioxide, not oxygen. Ribosomes are only involved in protein synthesis, with no role in oxygen production or release. Finally, the option Both A and B is misleading because it incorrectly suggests that both mitochondria and chloroplasts release oxygen, which is not true.

• A. SER less
• B. RER more
• C. RER less
• D. Cytoplasm is more

Explanation: The sarcoplasmic reticulum (SR) is a specialized form of smooth endoplasmic reticulum found in muscle cells, primarily responsible for regulating calcium ions during muscle contraction. The correct answer is that sarcoplasmic reticulum cells contain less rough endoplasmic reticulum (RER) compared to their smooth endoplasmic reticulum (SER). The other options are incorrect as they either misinterpret the relationship between RER and SER in muscle cells or do not focus on the defining characteristics of the sarcoplasmic reticulum.

• A. It contains F1 particles
• B. It is double membranous
• C. It is a self-replicating organelle
• D. The number of mitochondria is constant

Explanation: The correct answer is that the number of mitochondria is not constant. Different cell types and different conditions can lead to changes in the number of mitochondria within a cell. For example, muscle cells may have more mitochondria due to higher energy demands. The other options describe true characteristics of mitochondria: they contain F1 particles for ATP production, they have a double membrane structure essential for their function, and they are capable of self-replication due to their own DNA.

• A. Grana
• B. Cristae
• C. Thylakoid membrane
• D. Intergrana

Explanation: The correct answer is cristae. The cristae are folds of the inner membrane of mitochondria, which increase the surface area for chemical reactions such as cellular respiration. Grana, thylakoid membranes, and intergrana are all associated with chloroplasts, which are involved in photosynthesis, not with mitochondria.