Q1: What is the primary function of the Golgi apparatus in a cell? (a) Protein synthesis (b) Energy production (c) Modifying, sorting, and packaging proteins and lipids (d) Breaking down waste materials
Solution:
Ans: (c) Explanation: The Golgi apparatus modifies, sorts, and packages proteins and lipids received from the ER into vesicles for transport, secretion, or lysosome formation.
Q2: Which scientist first observed cells using a self-designed microscope in 1665? (a) Camillo Golgi (b) Robert Hooke (c) Rudolf Virchow (d) Matthias Schleiden
Solution:
Ans: (b) Explanation: Robert Hooke first observed cells in 1665 using a self-designed microscope with 200-300X magnification while examining a thin slice of cork.
Q3: What happens to a plant cell when placed in a hypertonic solution? (a) The cell wall collapses completely (b) The cell membrane pulls away from the cell wall (c) The cell bursts due to excess water entry (d) The cell remains unchanged
Solution:
Ans: (b) Explanation: In a hypertonic solution, water leaves the plant cell by osmosis, causing the cell membrane to pull away from the cell wall, a process called plasmolysis.
Q4: How many daughter cells are produced during meiosis? (a) 2 (b) 4 (c) 6 (d) 8
Solution:
Ans: (b) Explanation: Meiosis produces four daughter cells, each with half the number of chromosomes as the parent cell, which is essential for sexual reproduction.
Q5: Which organelle is known as the powerhouse of the cell? (a) Mitochondria (b) Chloroplast (c) Nucleus (d) Ribosome
Solution:
Ans: (a) Explanation: Mitochondria are called the powerhouse of the cell because they break down glucose during cellular respiration and produce ATP, the energy currency of the cell.
Fill in the Blanks
Q1: The cell membrane is described by the _____ model.
Solution:
Ans: Fluid Mosaic
Q2: Chromosomes are made of DNA and _____.
Solution:
Ans: proteins
Q3: The green pigment present in chloroplasts is called _____.
Solution:
Ans: chlorophyll
Q4: The finger-like folds of the inner mitochondrial membrane are called _____.
Solution:
Ans: cristae
Q5: The process by which water moves through a selectively permeable membrane from dilute to concentrated solution is called _____.
Solution:
Ans: osmosis
True or False
Q1: Prokaryotic cells have a well-defined nucleus surrounded by a nuclear membrane.
Solution:
Ans: False Explanation: Prokaryotic cells lack a well-defined nucleus; they only have a nucleoid region where circular DNA is located without any surrounding membrane.
Q2: Both mitochondria and plastids contain their own DNA and ribosomes.
Solution:
Ans: True Explanation: Mitochondria and plastids both have their own DNA and ribosomes, suggesting they share an evolutionary history with ancient free-living bacteria.
Q3: Animal cells have a rigid cell wall made of cellulose.
Solution:
Ans: False Explanation: Animal cells do not have a cell wall; only plant cells, fungal cells, and bacterial cells possess this rigid outer covering.
Q4: Mature red blood cells in humans lack a nucleus.
Solution:
Ans: True Explanation: Mature human red blood cells have no nucleus, which provides more space for haemoglobin to transport oxygen, but limits their lifespan to 120 days.
Q5: Mitosis produces four genetically different daughter cells.
Solution:
Ans: False Explanation: Mitosis produces two genetically identical daughter cells with the same number of chromosomes as the parent cell for growth and repair.
Match the Following
Column A
Column B
1. Ribosomes
A. Packaging and shipping centre of the cell
2. Lysosomes
B. Storage organelle with cell sap in plants
3. Golgi apparatus
C. Clean-up system with digestive enzymes
4. Vacuoles
D. Site of protein synthesis
5. Endoplasmic Reticulum
E. Network for synthesis and transport of proteins and lipids
Solution:
Ans:
1 - D: Ribosomes are tiny structures that function as the site of protein synthesis using instructions from DNA in both prokaryotic and eukaryotic cells.
2 - C: Lysosomes are single membrane-bound sacs filled with digestive enzymes that break down unwanted materials and damaged cell parts, acting as the cell's clean-up system.
3 - A: The Golgi apparatus modifies, sorts, and packages proteins and lipids into vesicles for transport and secretion, functioning like the post office of the cell.
4 - B: Vacuoles in plant cells are large central organelles filled with cell sap that store water, minerals, sugars, and maintain turgor pressure for support.
5 - E: The endoplasmic reticulum is a large network organelle that spreads through the cytoplasm and functions in synthesis and transport of proteins and lipids.
Short Answer Questions
Q1: What is the Fluid Mosaic Model and why is the cell membrane described using this model?
Solution:
Ans: The Fluid Mosaic Model describes the structure of the cell membrane. It consists of a lipid bilayer with two layers of fat molecules having water-attracting heads pointing outward and water-repelling tails pointing inward. Proteins are embedded in this bilayer and act as gatekeepers. The molecules can move sideways, flip, and rotate, making it fluid, and are arranged like mosaic tiles.
Q2: Explain the difference between prokaryotic and eukaryotic cells based on their nuclear structure.
Solution:
Ans: Prokaryotic cells lack a well-defined nucleus and have their DNA present as a single circular molecule in a region called the nucleoid, which is not enclosed by any membrane. Eukaryotic cells have a well-defined nucleus surrounded by a double-layered nuclear membrane with nuclear pores. Prokaryotic cells are primitive and smaller, while eukaryotic cells are larger and contain membrane-bound organelles.
Q3: Why do mitochondria have cristae, and what is their significance?
Solution:
Ans: Mitochondria have cristae, which are finger-like projections of the inner mitochondrial membrane. These folds increase the surface area available for chemical reactions during cellular respiration. Greater surface area allows more space for reactions and faster energy production in the form of ATP. This efficient structure makes mitochondria effective as the powerhouse of the cell, supplying energy for cellular activities.
Q4: What is osmosis and how does it affect a potato piece placed in plain water?
Solution:
Ans: Osmosis is the diffusion of water through a selectively permeable membrane from an area of more water to an area of less water until concentrations become equal. When a potato piece is placed in plain water, the solution outside is hypotonic with lower solute concentration than inside. Water enters the potato cells by osmosis, causing the cells to swell and the potato piece to become turgid.
Q5: State the Classical Cell Theory and name the scientists who contributed to it.
Solution:
Ans: The Classical Cell Theory states that all living organisms are made up of one or more cells, the cell is the basic unit of structure and function, and all cells arise from pre-existing cells. Matthias Schleiden proposed in 1838 that all plants are made of cells. Theodor Schwann stated in 1839 that all animals are made of cells. Rudolf Virchow concluded in 1855 that new cells arise only from pre-existing cells.
Long Answer Questions
Q1: Compare and contrast mitosis and meiosis in terms of their purpose, number of daughter cells produced, and genetic similarity.
Solution:
Ans:
Mitosis produces two daughter cells, while meiosis produces four daughter cells.
In mitosis, daughter cells have the same number of chromosomes as the parent and are genetically identical, whereas in meiosis, daughter cells have half the chromosomes and are genetically different.
Mitosis occurs in all body cells for growth, repair, and maintenance, while meiosis occurs only in reproductive organs for sexual reproduction.
Mitosis maintains genetic information across cells, while meiosis creates genetic diversity essential for variation in offspring.
Q2: Analyse the structural features of chloroplasts and explain how they are adapted for photosynthesis.
Solution:
Ans:
Chloroplasts are double-membrane bound organelles found only in plant cells and some algae.
They contain a semi-fluid substance called stroma where sugars and starch are stored after photosynthesis.
Within the stroma are disc-shaped membrane structures containing chlorophyll, the green pigment that absorbs light energy.
This structural organisation allows efficient capture of light energy and conversion into chemical energy through photosynthesis.
Like mitochondria, chloroplasts have their own DNA and ribosomes, suggesting an evolutionary origin from ancient bacteria.
Q3: Evaluate the importance of cell division and explain what happens when cell division goes wrong.
Solution:
Ans:
Cell division allows organisms to grow, repair damaged tissues, and reproduce by forming new cells from pre-existing ones.
Normal cells divide in a controlled manner and stop when they contact neighbouring cells, called contact inhibition.
Every day, hundreds of billions of cells are replaced, maintaining body functions.
When errors occur in mitosis, uncontrolled cell divisions lead to tumours and abnormal chromosome numbers, potentially causing cancer.
Errors in meiosis can cause genetic disorders, developmental problems, and reduced fertility, affecting reproduction and offspring health.
ppt, practice quizzes, Summary, mock tests for examination, Sample Paper, Previous Year Questions with Solutions, MCQs, shortcuts and tricks, Extra Questions, Important questions, Worksheet with Solutions: Cell: The Building Block of Life, Exam, Viva Questions, Free, past year papers, pdf , study material, Objective type Questions, Semester Notes, Worksheet with Solutions: Cell: The Building Block of Life, video lectures, Worksheet with Solutions: Cell: The Building Block of Life;
