Fundamental Units of Life - MCQ Quiz
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Monday, 28 April 2025
April 28, 2025
MCQ Quiz: Fundamental Units of Life
1. Who first discovered cells?
Correct Answer: Robert Hooke
Robert Hooke discovered cells in 1665 when he examined a thin slice of cork under a microscope and observed small compartments which he called "cells".
2. Which of these is NOT a principle of cell theory?
Correct Answer: All cells have a nucleus
Prokaryotic cells do not have a nucleus, so this cannot be a principle of cell theory. The three main principles are that all organisms are made of cells, cells are the basic unit of life, and all cells come from pre-existing cells.
3. Which organelle is known as the "powerhouse of the cell"?
Correct Answer: Mitochondria
Mitochondria are called the powerhouse of the cell because they generate most of the cell's supply of ATP, which is used as a source of chemical energy.
4. Which of these cells would contain the most mitochondria?
Correct Answer: Muscle cell
Muscle cells contain many mitochondria because they require large amounts of energy for contraction. Red blood cells actually have no mitochondria.
5. What is the function of ribosomes?
Correct Answer: Protein synthesis
Ribosomes are the cellular structures responsible for protein synthesis, where they translate mRNA into polypeptide chains.
6. Which structure is found in plant cells but not animal cells?
Correct Answer: Chloroplast
Chloroplasts are organelles found in plant cells that conduct photosynthesis. Animal cells do not have chloroplasts because they do not perform photosynthesis.
7. What is the function of the Golgi apparatus?
Correct Answer: Modifying, sorting and packaging proteins
The Golgi apparatus modifies proteins and lipids that it receives from the endoplasmic reticulum and prepares them for export outside the cell or for transport to other locations in the cell.
8. Which of these is NOT a difference between prokaryotic and eukaryotic cells?
Correct Answer: Presence of DNA
Both prokaryotic and eukaryotic cells contain DNA. The main differences are that eukaryotes have a nucleus and membrane-bound organelles, while prokaryotes do not.
9. What is the main component of the cell membrane?
Correct Answer: Phospholipids
The cell membrane is primarily composed of a phospholipid bilayer, which forms a semi-permeable barrier around the cell.
10. Which process allows white blood cells to engulf bacteria?
Correct Answer: Phagocytosis
Phagocytosis is the process by which cells engulf large particles such as bacteria. White blood cells use this process to destroy pathogens.
11. What is the function of lysosomes?
Correct Answer: Cellular digestion
Lysosomes contain digestive enzymes that break down waste materials and cellular debris, acting as the cell's waste disposal system.
12. Which organelle is responsible for photosynthesis?
Correct Answer: Chloroplast
Chloroplasts contain chlorophyll and are the sites of photosynthesis in plant cells, converting light energy into chemical energy.
13. What is the jelly-like substance inside the cell called?
Correct Answer: Cytoplasm
The cytoplasm is the jelly-like substance that fills the cell and contains all the organelles. It's composed mainly of water, salts, and proteins.
14. Which of these is NOT a function of the cell membrane?
Correct Answer: Producing ATP
ATP production occurs in mitochondria, not in the cell membrane. The membrane's functions include regulation, support, and recognition.
15. What is the function of the endoplasmic reticulum?
Correct Answer: Protein synthesis and transport
The ER, especially the rough ER with ribosomes, is involved in protein synthesis and transport within the cell. Smooth ER is involved in lipid synthesis.
16. Which of these cells lacks a nucleus?
Correct Answer: Bacterial cell
Bacterial cells are prokaryotic and lack a true nucleus. Their DNA is located in the nucleoid region instead of being enclosed in a nuclear membrane.
17. What is the function of the nucleolus?
Correct Answer: Ribosome production
The nucleolus is a region within the nucleus responsible for producing and assembling ribosome components.
18. Which structure gives plant cells their rigid shape?
Correct Answer: Cell wall
The cell wall, composed mainly of cellulose, provides structural support and rigidity to plant cells, allowing them to maintain their shape.
19. What is the function of the cytoskeleton?
Correct Answer: Cellular movement and structure
The cytoskeleton is a network of protein filaments that provides structural support, enables cell movement, and facilitates intracellular transport.
20. Which of these is NOT found in animal cells?
Correct Answer: Cell wall
Animal cells lack a cell wall, which is present in plant cells, fungi, and bacteria. Animal cells have a flexible cell membrane instead.
21. What is the function of the central vacuole in plant cells?
Correct Answer: Storage and maintaining turgor pressure
The central vacuole stores water, nutrients, and waste products. It also helps maintain turgor pressure against the cell wall, keeping the plant rigid.
22. Which organelle contains the cell's genetic material?
Correct Answer: Nucleus
The nucleus contains the cell's genetic material (DNA) in eukaryotic cells. In prokaryotes, the DNA is located in the nucleoid region.
23. What is the movement of water across a semi-permeable membrane called?
Correct Answer: Osmosis
Osmosis is the movement of water molecules across a semi-permeable membrane from an area of lower solute concentration to higher solute concentration.
24. Which of these is NOT a type of passive transport?
Correct Answer: Endocytosis
Endocytosis is an active transport process that requires energy (ATP), while osmosis, diffusion, and facilitated diffusion are passive processes.
25. What is the function of chloroplasts?
Correct Answer: Photosynthesis
Chloroplasts contain chlorophyll and are the sites of photosynthesis in plant cells, converting light energy into chemical energy stored in glucose.
26. Which of these is NOT a component of the cell theory?
Correct Answer: All cells have the same organelles
Different types of cells have different organelles based on their function. For example, plant cells have chloroplasts while animal cells do not.
27. What is the function of the nuclear envelope?
Correct Answer: Separating nucleus from cytoplasm
The nuclear envelope is a double membrane that separates the nucleus and its contents from the cytoplasm, regulating what enters and exits the nucleus.
28. Which of these is NOT a function of the smooth endoplasmic reticulum?
Correct Answer: Protein synthesis
Protein synthesis occurs on ribosomes, which are found on the rough ER, not the smooth ER. The smooth ER is involved in lipid synthesis, detoxification, and calcium storage.
29. What is the function of cilia and flagella?
Correct Answer: Cell movement
Cilia and flagella are hair-like structures that help in cell movement. Cilia are short and numerous, while flagella are longer and fewer in number.
30. Which of these is NOT a difference between plant and animal cells?
Correct Answer: Presence of mitochondria
Both plant and animal cells contain mitochondria. The main differences are that plant cells have cell walls, chloroplasts, and larger vacuoles.
31. What is the function of peroxisomes?
Correct Answer: Breakdown of fatty acids and detoxification
Peroxisomes contain enzymes that break down fatty acids and detoxify harmful substances like hydrogen peroxide in the cell.
32. Which process requires energy to move molecules against their concentration gradient?
Correct Answer: Active transport
Active transport moves molecules against their concentration gradient (from low to high concentration) and requires energy in the form of ATP.
33. What is the function of chromatin?
Correct Answer: Package and organize DNA
Chromatin is the complex of DNA and proteins (histones) that packages DNA into a smaller volume to fit in the cell and controls gene expression.
34. Which of these is NOT a function of the plasma membrane?
Correct Answer: Protein synthesis
Protein synthesis occurs at ribosomes, not in the plasma membrane. The membrane's functions include regulation, recognition, and signaling.
35. What is the function of centrioles?
Correct Answer: Organizing microtubules during cell division
Centrioles help organize microtubules of the spindle apparatus during cell division (mitosis and meiosis) in animal cells.
36. Which structure is responsible for protein modification and sorting?
Correct Answer: Golgi apparatus
The Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or for transport to other organelles.
37. What is the function of the nucleoid region in prokaryotic cells?
Correct Answer: Contains the cell's DNA
The nucleoid is the irregularly-shaped region in prokaryotic cells where the genetic material (DNA) is located, not enclosed by a nuclear membrane.
38. Which of these is NOT a component of the cytoskeleton?
Correct Answer: Cellulose fibers
The cytoskeleton is composed of microtubules, microfilaments, and intermediate filaments. Cellulose is a component of plant cell walls, not the cytoskeleton.
39. What is the function of plasmodesmata in plant cells?
Correct Answer: Cell-to-cell communication and transport
Plasmodesmata are channels through plant cell walls that allow transport and communication between adjacent plant cells.
40. Which of these is NOT a function of membrane proteins?
Correct Answer: DNA replication
DNA replication occurs in the nucleus, not at the membrane. Membrane proteins are involved in transport, recognition, and enzymatic activities.
41. What is the function of gap junctions in animal cells?
Correct Answer: Intercellular communication
Gap junctions are specialized intercellular connections that allow direct communication and transport between animal cells.
42. Which organelle is responsible for breaking down hydrogen peroxide?
Correct Answer: Peroxisome
Peroxisomes contain catalase, an enzyme that breaks down hydrogen peroxide (a toxic byproduct of metabolism) into water and oxygen.
43. What is the function of cholesterol in the cell membrane?
Correct Answer: Maintain membrane fluidity
Cholesterol helps maintain membrane fluidity by preventing fatty acid chains from packing too closely together at low temperatures or separating too much at high temperatures.
44. Which of these is NOT a difference between rough and smooth ER?
Correct Answer: Presence in both plant and animal cells
Both rough and smooth ER are present in plant and animal cells. The main differences are the presence of ribosomes and their primary functions.
45. What is the function of the nuclear pore complex?
Correct Answer: Regulate movement between nucleus and cytoplasm
Nuclear pores regulate the transport of molecules (like RNA and proteins) between the nucleus and the cytoplasm.
46. Which of these is NOT a function of the extracellular matrix in animal cells?
Correct Answer: Photosynthesis
Photosynthesis occurs in chloroplasts, not in the extracellular matrix. The ECM provides support, facilitates signaling, and helps organize tissues.
47. What is the function of tight junctions in animal cells?
Correct Answer: Create a watertight seal between cells
Tight junctions form continuous seals around cells to prevent leakage of extracellular fluid across epithelial cell layers.
48. Which of these is NOT a component of the endomembrane system?
Correct Answer: Mitochondria
Mitochondria are not part of the endomembrane system, which includes the nuclear envelope, ER, Golgi, lysosomes, vesicles, and plasma membrane.
49. What is the function of the thylakoid membranes in chloroplasts?
Correct Answer: Light-dependent reactions
Thylakoid membranes contain chlorophyll and are the site of the light-dependent reactions of photosynthesis where light energy is converted to chemical energy.
50. Which of these is NOT a function of the cell wall in plant cells?
Correct Answer: Facilitate cell communication
While the cell wall provides support, maintains shape, and helps prevent water loss, cell communication occurs through plasmodesmata, not the cell wall itself.
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