Case Study Questions Class 9 Science Chapter 5 The Fundamental Unit of Life
CBSE Class 9 Case Study Questions Science The Fundamental Unit of Life. Important Case Study Questions for Class 9 Exam. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions The Fundamental Unit of Life.
At Case Study Questions there will given a Paragraph. In where some Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks or 4 marks.
CBSE Case Study Questions Class 9 Science – The Fundamental Unit of Life
CASE 1
All living Organisms are made up of cells and these cells perform all the functions essential for the survival of the Organism eg. Respiration, digestion, excretion etc. In Unicellular organisms, a single cell carries out all these functions and in multicellular organisms different group of cells carry out different functions.
Cells were first discovered by Robert Hooke in 1665. He observed the cells in a cork slice with the help of a primitive microscope. Leeuwenhoek (1674), with the improved microscope, discovered the free living cells in pond water for the first time. It was Robert Brown in 1831 who discovered the nucleus in the cell. Purkinje in 1839 coined the term ‘protoplasm’ for the fluid substance of the cell.
(1) Who discovered the cell?
(a) Robert Hooke
(b) Leeuwenhoek
(c) Robert Brown
(d) T. Schwann
(2) Who discovered the nucleus in the cell?
(a) Robert Hooke
(b) Leeuwenhoek
(c) Robert Brown
(d) T. Schwann
(3) Who coined the term ‘Protoplasm’?
(a) Robert Hooke
(b) Leeuwenhoek
(c) Robert Brown
(d) Purkinje
(4) What is protoplasm?
(a) Unit of life
(b) Cell organelle
(c) Fluid substance of the cell.
(d) Cytoplasm
(5) Which of these statement is true about the cell?
(a) All organism are made up of cell
(b) Cell is the basic unit of life
(c) Cell is responsible for different metabolic functions
(d) All above
Answer Key
(1) a
(2) c
(3) d
(4) c
(5) d
CASE 2
The cell theory, that all the plants and animals are composed of cells and that the cell is the basic unit of life, was presented by two biologists, German zoologist Schleiden (1838) and British zoologist Schwann (1839). The cell theory was further expanded by Virchow (1855) by suggesting that all cells arise from pre-existing cells. With the discovery of the electron microscope in 1940, it was possible to observe and understand the complex structure of the cell and its various organelles.
(1) Theodore Schwann was a _____
(a) British zoologist
(b) German zoologist
(c) British botanist
(d) German botanist
(2) Matthias Schleiden was a _____
(a) German zoologist
(b) British zoologist
(c) German botanist
(d) British botanist
(3) Which of these scientists formulated the cell theory?
(a) Schleiden and Schwann
(b) Rudolf Virchow
(c) Robert Koch
(d) Antony Von Leeuwenhoek
(4) Which scientist was the first to explain that new cells arise from pre-existing cells?
(a) Antony Von Leeuwenhoek
(b) Matthias Schleiden
(c) Rudolph Virchow
(d) Theodore Schwann
(5) Which of these scientists did not contribute to the cell theory?
(a) Robert Koch
(b) Matthias Schleiden
(c) Theodore Schwann
(d) Rudolph Virchow
Answer Key
(1) a
(2) a
(3) a
(4) c
(5) a
CASE 3
Plasma membrane or Cell membrane is the outermost covering of the cell that separates the contents of the cell from its external environment. The plasma membrane is flexible and is made up of organic molecules called lipids and proteins. The flexibility of the cell membrane also enables the cell to engulf in food and other material from its external environment. Such processes are known as endocytosis.The plasma membrane allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. The cell membrane, therefore, is called a selectively permeable membrane.
Some substances like carbon dioxide or oxygen can move across the cell membrane by a process called diffusion. There is spontaneous movement of a substance from a region of high concentration to a region where its concentration is low. Similar thing happens in cells – some substance like CO2 (carbon dioxide is cellular waste and requires to be excreted out by the cell) accumulates in high concentrations inside the cell. In the cell’s external environment, the concentration of CO2 is low as compared to that inside the cell. As soon as there is a difference of concentration of CO2 inside and outside a cell, CO2 moves out of the cell, from a region of high concentration, to a region of low concentration outside the cell by the process of diffusion.
Water obeys the law of diffusion. The movement of water molecules through such a selectively permeable membrane is called osmosis. The movement of water across the plasma membrane is also affected by the amount of substance dissolved in water. Thus, osmosis is the net diffusion of water across a selectively permeable membrane toward a higher solute concentration.
(1) The plasma membrane is made up of ___________
(a) Proteins
(b) Lipids
(c) Proteins and Lipids (Lipoproteins)
(d) none of above
(2) Which of the following substance is known as cellular waste?
(a) Oxygen
(b) Nitrogen
(c) Carbon dioxide
(d) None of above
(3) The movement of a substance from the region of higher concentration to the region where its concentration is lower is called as _____________
(a) Osmosis
(b) Diffusion
(c) Excretion of CO2 (carbon dioxide)
(d) All above
(4) Why cell membrane is known as selectively permeable membrane?
(5) What is mean by diffusion?
(6) Define Osmosis.
Answer key
(a) c
(b) c
(c) b
(d) Cell membrane allows or permits the entry and exit of some materials in and out of the cell. It also prevents movement of some other materials. Hence it is called as selectively permeable membrane.
(e) It is spontaneous movement of a substance from a region of high concentration to a region where its concentration is low. For example, some substances like carbon dioxide or oxygen can move across the cell membrane by a process called diffusion.
CASE 4
Plant cells, in addition to the plasma membrane, have another rigid outer covering called the cell wall. The cell wall lies outside the plasma membrane. The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants. When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis.
(1) Which of the following is the main constituent of cell wall?
(a) Proteins
(b) Lipids
(c) Lipoproteins
(d) Cellulose
(2) Which of the following is outer most covering of the plant cell?
(a) Cell membrane
(b) Plasma membrane
(c) Cell wall
(d) Cellulose
(3) Choose the correct set of statements from the following.
Statement 1 – Cell wall lies outside the plasma membrane.
Statement 2 – Cell wall is mainly composed of cellulose.
Statement 3 – Cellulose is a complex substance and provides structural strength to plants.
Statement 4 – Cell wall lies outside the plasma membrane.
(a) Statement 1 & 3
(b) Statement 1 & 2
(c) Statement 3 & 4
(d) All statement are correct
(4) What is mean by plasmolysis?
(5) What is the reason behind structural strength of plant cell?
Answer key
(1) d
(2) c
(3) d
(4) When living plant cell loses water through osmosis there is contraction of the contents of the cell away from the cell wall. This phenomenon is called as plasmolysis.
(5) The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants.
CASE 5
Every cell has a membrane around it to keep its own contents separate from the external environment. Large and complex cells, including cells from multicellular organisms, need a lot of chemical activities to support their complicated structure and function. To keep these activities of different kinds separate from each other, these cells use membrane-bound little structures within themselves. The cytoplasm is the jelly like fluid content inside the plasma membrane which contains many specialised cell organelles. Such as Endoplasmic Reticulum, Golgi apparatus, Lysosomes, Ribosomes, Nucleus, Chloroplast, Mitochondria and Plastids.Each of these organelles performs a specific function for the cell. Some of these organelles are visible only with an electron microscope. They are important because they carry out some very crucial functions in cells.
(1) Identify the statement which is true for cells.
Statement 1 – Some cell organelles are visible only with an electron microscope.
Statement 2 – Cytoplasm is jelly like fluid present inside the cell.
Statement 3 – Cell organelles perform all the functions in cell.
Statement 4 – Every cell has a membrane around it to keep its own contents separate from the external environment.
(a) Statement 1 & 3
(b) Statement 2 & 4
(c) Statement 1 & 4
(d) All statement are true.
(2) A suitable term for the various components of cells is ________
(a) tissue
(b) cell organelles
(c) chromosomes
(d) genes
(3) The jelly-like fluid substance present in cells is called __________
(a) Protoplasm
(b) Chromosome
(c) Chloroplast
(d) Cytoplasm
(4) What is cell organelles?
(5) Enlist the any five cell organelles.
Answer key
(1) D
(2) B
(3) D
(4) Cell organelles are the specialized organelles present with in the cells these organelles are involved in carrying out essential functions.
(5) Endoplasmic Reticulum, Golgi apparatus, Lysosomes, Ribosomes, Nucleus, Chloroplast, Mitochondria and Plastids.
CASE 6
The endoplasmic reticulum is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags (vesicles). It is discovered by Porter and Thompson. The ER membrane is similar in structure to the plasma membrane. There are two types of ER– rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). RER looks rough under a microscope because it has particles called ribosomes attached to its surface. The ribosomes, which are present in all active cells, are the sites of protein manufacture. The manufactured proteins are then sent to various places in the cell depending on need, using the ER. The SER helps in the manufacture of fat molecules, or lipids, important for cell function. Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis. Some other proteins and lipids function as enzymes and hormones. Although the ER varies greatly in appearance in different cells, it always forms a network system.
(1) Who discovered endoplasmic reticulum?
(a) Porter and Thompson
(b) Robert Brown
(c) Robert Hooke
(d) Koshland
(2) Which are the components of endoplasmic reticulum__________
(a) Cisternae, tubules and vesicles.
(b) Cisternae, chromatids and vacuoles
(c) Both a and b
(d) None of the above
(3) Endoplasmic reticulum membrane which is associated with ribosomes is called_______
(a) ER lumen
(b) Smooth endoplasmic reticulum
(c) Rough endoplasmic reticulum
(d) Endosome
(4) Enlist the types of Endoplasmic Reticulum.
(5) Define membrane biogenesis?
Answer key
(1) A
(2) A
(3) C
(4) Smooth endoplasmic reticulum and Rough endoplasmic reticulum
(5) The SER helps in the manufacture of fat molecules, or lipids, important for cell function. Some of these proteins and lipids help in building the cell membrane. This process is known as membrane biogenesis.
CASE 7
The Golgi apparatus, first described by Camilo Golgi, consists of a system of membrane-bound vesicles (flattened sacs) arranged approximately parallel to each other in stacks called cisterns. These membranes often have connections with the membranes of ER and therefore constitute another portion of a complex cellular membrane system. The material synthesised near the ER is packaged and dispatched to various targets inside and outside the cell through the Golgi apparatus. Its functions include the storage, modification and packaging of products in vesicles. In some cases, complex sugars may be made from simple sugars in the Golgi apparatus. The Golgi apparatus is also involved in the formation of lysosomes
(1) Who discovered endoplasmic reticulum?
(a) Porter and Thompson
(b) Robert Brown
(c) Robert Hooke
(d) Camilo Golgi
(2) A system of membrane-bound flattened sacs arranged approximately parallel to each other in stacks are called as _________
(a) Cisterns
(b) Vesicles
(c) Golgi complex
(d) Vacuoles
(3) Membrane bound flattened sacs is termed as _________
(a) Cisterns
(b) Vesicles
(c) Golgi complex
(d) Vacuoles
(4) Enlist the function of Golgi apparatus.
(5) Name the cell organelles which is involved in the formation of lysosomes?
Answer key
(1) d
(2) a
(3) b
(4) Functions of Golgi apparatus:
- Storage, modification and packaging of products
- Involved in formation of lysosomes
(5) Golgi apparatus
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