All Free Biology MCQs with Answers
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19844 questions · page 628 of 1985
6271. The oxygen and carbon dioxide crosses the plasma membrane through the process of _.
- A. Active diffusion
- B. Facilitated diffusion
- C. Passive diffusion
- D. Random diffusion
Explanation: Passive diffusion is the type of diffusion which takes place down the concentration gradient and there's no need of any Channel protein. Since the concentration of Oxygen entering the alveoli is greater whereas the concentration of oxygen entering the lungs through blood is lower, thus a concentration gradient created and oxygen diffuse from alveoli into the blood through the plasma membrane. Vice versa happens for Carbondioxide. Since, Oxygen and Carbondioxide are small, soluble polar molecules, they can easily cross the plasma membrane via Passive transport, marking this option to be correct.
Correct answer: Passive diffusion6272. What would be the resolving power of the objective lens in a microscope if the eyepiece is 10X and the total magnification is 40X?
- A. 4
- B. 10
- C. 40
- D. 400
Explanation: Total magnification= Magnification of eye piece x Magnification of objective 40= 10 x y 40/10= y y= 4 Answer
Correct answer: 46273. Which cell organelle is involved in apoptosis?
- A. Lysosomes
- B. ER
- C. Golgi
- D. Mitochondria
Explanation: Option A is correct as apoptosis is the process by which a cell dies, and "lysosomes" are organelles with special enzymes that break down the cell nearing its death.
Correct answer: Lysosomes6274. This jelly like substance inside the plasma membrane in which all cell organelles are floating is?
- A. Cytoplasm
- B. Tonoplasm
- C. Karyoplasm
- D. Cell sap
Explanation: Option A is correct as the fluid in which all organelles are suspended in a cell is called the "cytoplasm". It is mainly composed of water, salts and proteins and is enclosed by the cell membrane.
Correct answer: Cytoplasm6275. Under microscopic examination, which cellular structure would differentiate a plant cell from an animal cell?
- A. Nucleus
- B. Cell membrane
- C. Cytoplasm
- D. Cell vacuole
Explanation: Option D is correct as plant cells usually have only one ore two large "vacoules" in the centre. Animal cells have multiple small "vacoules" spread across the cytoplasm.
Correct answer: Cell vacuole6276. Transverse diffusion (flip-flop) is the movement of which of the following molecules?
- A. Cholestrol molecule
- B. Amino Acid
- C. Protein
- D. Phospholipid
Explanation: Transverse diffusion or flip-flop involves the movement of lipid or protein from one membrane surface to the other .
Correct answer: Phospholipid6277. The presence of which of the following feature would best indicate a eukaryotic cell?
- A. Cilia
- B. Membrane bound organelles
- C. Plasma membrane
- D. Ribosomes
Explanation: Option B is correct since eukaryotic cells always possess organelles that are membrane-bound. Option A is incorrect since only some eukaryotic cells may possess motile or nonmotile cilia. Therefore, cilia is not a necessary feature of all eukaryotic cells. Option C is incorrect since all prokaryotic cells also possess a plasma membrane. While the plasma membrane is a major component of all eukaryotic cells, the presence of a membrane in prokaryotes makes it difficult to differentiate between the two cells based on the cell membrane. Option D is incorrect since ribosomes are found in both prokaryotic and eukaryotic cells. In eukaryotes, 80S ribosomes are present while in prokaryotes, 70S ribosomes are present.
Correct answer: Membrane bound organelles6278. The cementing material between adjacent plant cells is:
- A. Cellulose
- B. Hemicellulose
- C. Middle Lamella
- D. All of the above
Explanation: Option C is correct since the middle lamella is the layer of material between adjacent plant cells. It cements the cells together and contains pectins, which are also used as gelling agents in food.
Correct answer: Middle Lamella6279. The organelle serving as a primary packaging area for molecules that will be distributed throughout the cell is?
- A. Vacuole
- B. Plastids
- C. Lysosomes
- D. Golgi apparatus
Explanation: The Golgi apparatus, or Golgi complex, is the organelle that serves as the primary packing and distribution center in eukaryotic cells. The Golgi apparatus is responsible for sorting, modifying, and packaging proteins and lipids that are synthesized in the endoplasmic reticulum (ER) and preparing them for transport to their final destinations within the cell or for secretion outside of the cell. The Golgi apparatus consists of a series of flattened, membrane-bound sacs called cisternae, which are organized into several distinct regions based on their function. The Golgi apparatus is an essential organelle that plays a crucial role in maintaining the structure and function of eukaryotic cells.
Correct answer: Golgi apparatus6280. The isolation of different cellular components to determine their chemical composition can be achieved by:
- A. Cell differentiation
- B. Chromatography
- C. Cell fractionation
- D. All of these
Explanation: The isolation of different cellular components to determine their chemical composition can be achieved by a technique called cell fractionation. Cell fractionation involves breaking open cells and separating their components based on size, shape, and density. This can be done using a variety of different methods, such as centrifugation, differential sedimentation, and chromatography. By separating the different cellular components, scientists can study their chemical composition and determine their functions within the cell.
Correct answer: Cell fractionation