Case Study 1: Discovery of Cell
In 1665, Robert Hooke observed thin slices of cork under his self-made microscope. He noticed tiny box-like structures that resembled a honeycomb. He called them “cells.” Later, scientists like Schleiden and Schwann proposed the cell theory, which stated that all living organisms are made up of cells and that cells are the basic structural and functional units of life.
Questions:
- The term “cell” was first used by:
(a) Schleiden (b) Schwann (c) Robert Hooke (d) Virchow
Answer: (c) - Cell theory was given by:
(a) Hooke and Leeuwenhoek (b) Schleiden and Schwann (c) Darwin and Mendel (d) Pasteur and Koch
Answer: (b) - Who added that all cells arise from pre-existing cells?
(a) Hooke (b) Schwann (c) Virchow (d) Mendel
Answer: (c) - Cell is the:
(a) largest unit of life (b) basic unit of life (c) smallest organ (d) none
Answer: (b) - Cells seen by Hooke were:
(a) living (b) dead (c) animal cells (d) bacterial cells
Answer: (b)
Case Study 2: Prokaryotic vs Eukaryotic Cells
Amit studied onion cells under a microscope and observed a well-defined nucleus surrounded by a nuclear membrane. Later, he studied bacterial cells and noticed that they lacked a true nucleus and had only a nucleoid. His teacher explained that onion cells are eukaryotic while bacterial cells are prokaryotic.
Questions:
- Nucleus with membrane is present in:
(a) prokaryotes (b) eukaryotes (c) both (d) none
Answer: (b) - Example of prokaryote = ?
(a) Amoeba (b) Bacteria (c) Onion (d) Human cell
Answer: (b) - DNA in prokaryotes is present in:
(a) nucleoid (b) nucleus (c) mitochondria (d) ribosomes
Answer: (a) - Cell wall is present in:
(a) bacteria (b) onion cell (c) both (d) animal cell
Answer: (c) - Which is absent in prokaryotes?
(a) ribosome (b) nucleus (c) plasma membrane (d) cytoplasm
Answer: (b)
Case Study 3: Cell Organelles – Mitochondria
During an experiment, students observed that when glucose was broken down in the cytoplasm, it released little energy. However, in the mitochondria, glucose was completely oxidized to release a large amount of energy in the form of ATP. Therefore, mitochondria are called the “powerhouse of the cell.”
Questions:
- Mitochondria are called:
(a) kitchen of cell (b) powerhouse (c) control centre (d) packaging centre
Answer: (b) - Energy is stored in the form of:
(a) DNA (b) RNA (c) ATP (d) proteins
Answer: (c) - Which gas is required for mitochondria to release energy?
(a) CO₂ (b) O₂ (c) H₂ (d) N₂
Answer: (b) - The process inside mitochondria = ?
(a) photosynthesis (b) respiration (c) protein synthesis (d) excretion
Answer: (b) - Mitochondria are:
(a) single-membrane bound (b) double-membrane bound (c) no membrane (d) none
Answer: (b)
Case Study 4: Plastids
Meera studied green leaves under the microscope and saw small green bodies called chloroplasts. Her teacher explained that chloroplasts contain chlorophyll, which helps in photosynthesis. Other plastids like chromoplasts provide colour to flowers and leucoplasts store food.
Questions:
- Green plastids are called:
(a) chloroplasts (b) chromoplasts (c) leucoplasts (d) none
Answer: (a) - Plastids are present in:
(a) animals only (b) plants only (c) both (d) none
Answer: (b) - Photosynthesis occurs in:
(a) mitochondria (b) chloroplasts (c) ribosomes (d) vacuoles
Answer: (b) - Plastids that store starch = ?
(a) chromoplasts (b) leucoplasts (c) chloroplasts (d) none
Answer: (b) - Plastids are:
(a) double-membrane bound (b) single-membrane bound (c) non-membranous (d) none
Answer: (a)
Case Study 5: Endoplasmic Reticulum (ER)
During cell study, Rohit saw a network of membranes. His teacher explained that rough ER has ribosomes and helps in protein synthesis, while smooth ER synthesizes lipids and helps in detoxification.
Questions:
- Rough ER is associated with:
(a) lipid synthesis (b) protein synthesis (c) DNA replication (d) photosynthesis
Answer: (b) - Ribosomes are attached to:
(a) smooth ER (b) rough ER (c) mitochondria (d) nucleus
Answer: (b) - Smooth ER synthesizes:
(a) carbohydrates (b) proteins (c) lipids (d) DNA
Answer: (c) - ER acts as:
(a) transport system (b) energy store (c) packaging centre (d) nucleus
Answer: (a) - Detoxification occurs in:
(a) mitochondria (b) smooth ER (c) ribosomes (d) lysosomes
Answer: (b)
Case Study 6: Golgi Apparatus
Shweta studied the Golgi apparatus and learned that it modifies, sorts, and packages proteins. It is also involved in the formation of lysosomes and secretion of enzymes and hormones.
Questions:
- Golgi apparatus is also called:
(a) packaging centre (b) powerhouse (c) control centre (d) kitchen
Answer: (a) - Lysosomes are formed by:
(a) nucleus (b) Golgi bodies (c) ER (d) ribosomes
Answer: (b) - Golgi modifies and packs:
(a) DNA (b) proteins (c) lipids (d) both b and c
Answer: (d) - Golgi apparatus is found in:
(a) plant cells (b) animal cells (c) both (d) none
Answer: (c) - Enzymes for secretion are packed in:
(a) nucleus (b) ribosomes (c) Golgi vesicles (d) lysosomes
Answer: (c)
Case Study 7: Lysosomes
During a biology lecture, the teacher explained that lysosomes contain powerful digestive enzymes and are called the “suicidal bags” of the cell. They help in breaking down waste and dead organelles.
Questions:
- Lysosomes contain:
(a) digestive enzymes (b) DNA (c) ATP (d) chlorophyll
Answer: (a) - Lysosomes are formed by:
(a) ER (b) Golgi apparatus (c) nucleus (d) ribosomes
Answer: (b) - They are called suicidal bags because:
(a) they store DNA (b) they digest own cell (c) they kill bacteria (d) none
Answer: (b) - Lysosomes are bounded by:
(a) single membrane (b) double membrane (c) no membrane (d) none
Answer: (a) - Main function = ?
(a) photosynthesis (b) protein synthesis (c) digestion of waste (d) respiration
Answer: (c)
Case Study 8: Vacuoles
In plant cells, large central vacuoles are filled with cell sap and provide turgidity. In animal cells, vacuoles are smaller. Vacuoles store waste, ions, and nutrients.
Questions:
- Vacuole in plant cell is:
(a) small (b) large central (c) absent (d) none
Answer: (b) - Vacuoles in animals are:
(a) large (b) small (c) absent (d) both a and b
Answer: (b) - Vacuole stores:
(a) enzymes (b) DNA (c) cell sap (d) chlorophyll
Answer: (c) - Vacuoles help in:
(a) photosynthesis (b) respiration (c) providing turgidity (d) none
Answer: (c) - Contractile vacuoles in Amoeba help in:
(a) photosynthesis (b) osmoregulation (c) digestion (d) reproduction
Answer: (b)
Case Study 9: Cell Membrane and Cell Wall
Sunil compared animal and plant cells. He observed that plant cells have both a cell wall and cell membrane, while animal cells have only a cell membrane. The cell membrane is selectively permeable, while the cell wall provides rigidity and support.
Questions:
- Cell wall is present in:
(a) plants (b) animals (c) both (d) none
Answer: (a) - Cell wall is made of:
(a) cellulose (b) protein (c) lipid (d) starch
Answer: (a) - Cell membrane is:
(a) permeable (b) impermeable (c) selectively permeable (d) none
Answer: (c) - Function of cell wall:
(a) control transport (b) provide rigidity (c) respiration (d) energy release
Answer: (b) - Cell membrane is also called:
(a) nuclear membrane (b) plasma membrane (c) vacuolar membrane (d) none
Answer: (b)
Case Study 10: Nucleus
Aditi observed a stained onion peel under the microscope and identified a dark body inside the cell called the nucleus. It contained chromatin material and a nucleolus. The nucleus controls all activities of the cell and contains hereditary material (DNA).
Questions:
- Nucleus was first discovered by:
(a) Robert Hooke (b) Robert Brown (c) Schleiden (d) Schwann
Answer: (b) - Chromosomes are made of:
(a) proteins (b) DNA (c) RNA (d) both a and b
Answer: (d) - Nucleolus helps in synthesis of:
(a) DNA (b) ribosomes (c) ATP (d) proteins
Answer: (b) - Nucleus is surrounded by:
(a) nuclear membrane (b) cell wall (c) cell membrane (d) none
Answer: (a) - Nucleus is called:
(a) powerhouse (b) control centre (c) packaging unit (d) none
Answer: (b)