1. All organisms consist of its unit called.
2. Roots, steams, leaves, and flowers are organs of plants.
 3. Hands, feet, legs, heart, kidney etc. are animal organs.
 4. All organs are made up of tissues which in turn are made up of cells.
 5. Though organisms differ in shape and size, these are all made up of basic units called cells.
 6. Cells present in living organism differ in numbers, shape and size.
 7. Bacteria (PPLO) has the smallest cell size of 0.1 micron. Ostrich egg has the largest cell size of 170 mm.
 8. The shape of cells varies from spherical, cuboidal, columnar to long and branched types.
 9. There are unicellular organisms (bacteria) as well as multicellular organisms (plants and animals).
10. Each cell has smaller parts called organelles. Some of these are common to different cell types. Each organelle has its own specific function.
11. Both plant and animal cells have plasma membrane, nucleus, mitochondria and vacuoles. Plant cells have, besides, cell wall and plastids.
12. Cell is basic structural and functional units of all living organisms.
13. Unicellular is the organism like bacteria containing only single cell.
14. Multicellular is the organism like plants and animals containing large number of cells.
15. Organelle is one of the smaller components of a cell.
16. Protoplasm is the viscous fluid inside the cell which provides living nature to it.
17. Plasma membrane is a membrane around the cell.
18. Cell wall is a covering of plasma membrane and found in plant cells only.
19. Nucleus is the denser region of the cell and may be present at the centre of the cell.
20. Nucleoplasm is the liquid material of the nucleus.
21. Nucleolus is a smaller, spherical, dense body inside the nucleus.
22. Chromosomes are thread like structures found in the nucleus.
      • There carry genes on them and help in inheritance or transfer of characters from the parents to the next generation.
      • Chromosomes can be seen only when cell divides.
23. Nucleus also acts as control centre for all the activities of the cell.
24. Prokaryotic Cells: The cells having nuclear material without nuclear membrane are termed prokaryotic cells.
25. Prokaryotes: The organisms with prokaryotic cells are called prokaryotes e.g., bacteria and blue green algae.
26. Eukaryotic Cells: The cells having nuclear material with nuclear membrane are called eukaryotic cells.
27. Euka ryotes: The organisms having eukaryotic cells are called eukaryotes.
28. Vacuoles: Are empty structures in the cytoplasm.
29. Large vacuoles are common in plant cells while animal cells have either no vacuoles or very small vacuoles.
30. Plastids are found in plant cells only.
31. Chloroplasts are the green colored plastids having chlorophyll which is essential for photosynthesis.
32. Plant cells differ from animal cells in having an additional layer over the cell membrane termed cell wall.

1. Indicate whether the following statements are True (T) or False (F):
    (a) Unicellular organisms have one-celled body.                      (T/F)
    (b) Muscle cells are branched.                                                   (T/F)
    (c) The basic living unit of an organism is an organ.                (T/F)
    (d) Amoeba has irregular shape.                                               (T/F)
Ans.(a) True     (b) False   (c) False (d) True.             
Q. 2. Make a sketch of the human nerve cell. What function do nerve cells perform?
Ans.Function of Nerve cells:
        The nerve cell receives and transfers messages, thereby helping to control and coordinate the working of different part of the body.
Fig. 8.1.Nerve cell
Q. 3. Write short notes on the following:
         (a) Cytoplasm
         (b) Nucleus of a cell
Ans.(a) Cytoplasm: This is jelly like substance found between the nucleus and the cell membrane. Various other components or organelles of cells are present in the cytoplasm. It is made up of basic elements like C, H, 0 and N. These are found in the form of substances like carbohydrates, proteins and water. These substances are present in all the cells of every organism irrespective of size, shape and whether they are unicellular or multicellular.
        (b) Nucleus of a Cell: It is an important component of the living cell. It is generally spherical and located in the centre of the cell. It can be stained and seen easily with the help of a microscope. Nucleus is separated from the cytoplasm by a membrane called the nuclear membrane. This membrane is also porous and allows the movement of materials between the cytoplasm and the inside of the nucleus.
              With a microscope of higher magnification, we can see a smaller spherical, dense body in the nucleus. It is called the nucleolus. In addition, nucleus contains thread-like structures called chromosomes. These carry genes and help in inheritance or transfer of characters from the parents to the next  generation. The chromosomes can be seen only when the cell divides.
              Nucleus, in addition to its role in inheritance, acts as control centre of the activities of the cell.
Q. 4. Which part of the cell contains organelles?
Q. 5. Make sketches of animal and plant cells. State three differences between them.

                                                           (a) Plant Cell                                           (b) Animal Call
Plant cellsAnimal cells
1. The outermost covering is cell wall which is made of cellulose.
2. Plastids (e.g., chloroplasts) present.
3. Large vacuoles present.
1. The outermost covering is the plasma membrane which is living material.
2. Plastids absent.
3. No or small vacuoles are present.
Q. 6. State the difference between eukaryotes and prokaryotes.
1. Nucleus of the cell has nuclear Membrane.
2. Possess membrane bound organelles.
3. Examples include all higher plants and animals.
1. Nucleus is not bound by membrane.
2. Membrane bound organelles are absent.
3. Examples are bacteria and blue green algae.
Q. 7. Where are chromosomes found in a cell? State their functions.
Ans.Chromosomes found in nucleus. Functions of chromosomes carry genes on them and help the transfer of character from parents to the next generation.
Q. 8. ‘Cells are the basic structural units of living organisms’. Explain.
Ans.Cells in the living organism are basic structural units. They have different designs, shape and sizes in the living organism. In living world, organism differ from one another cell but all are made up of cells. Cells in the living organism are complex living structure.
Q. 9. Explain why chloroplasts are found only in plant cells?
Ans.There are some colored bodies found in the cytoplasm of the cell of tradescantia leaf. These colored bodies are scattered in the cytoplasm of the leaf cells. These are called plastids. They are of different colors. Some of them contain green pigment called chlorophyll. Green colored plastids are called chloroplasts. They provide green color to the leaves. So we know that chlorophyll mostly found in plant cell. Therefore chloroplast found in plant cells.
Q. 10. Complete the crossword with the help of clues given below:
           1. This is necessary for photosynthesis.
           3. Term for component present in the cytoplasm.
           6. The living substance in the cell.
           8. Units of inheritance present on the chromosomes.
           1. Green plastids.
           2. Formed by collection of tissues.
           4. It separates the contents of the cell from the surrounding medium.
           5. Empty structure in the cytoplasm.
           7. A group of cells.


Q. 1. Which of the cells have larger vacuoles?
         (a) Plant cells
         (b) Animal cells
Ans.(a) Plant cells
Q. 2. Name the largest organelle.
Q. 3. What is the basic structural unit in living organisms?
Q. 4. Which organism has the smallest cell?
Ans.Bacteria (mycoplasmas).
Q. 5. Name the four elements, which form major part of protoplasm.
Ans.Carbon, hydrogen, nitrogen and oxygen.
Q. 6. Name the longest plant cell.
Ans.The fibre
Q. 7. Name the largest plant cell.
Q. 8. Name the outermost layer of an animal cell.
Ans.Plasma membrane
Q. 9. Mention the layer outside the plasma membrane of a plant cell.
Ans.Cell wall
Q. 10. Which four basic elements constitute 90% of protoplasm?
Ans.Carbon, hydrogen, nitrogen and oxygen.
Q. 11. What do mitochondria do in the cell?
Ans.Mitochondria in the cell provide energy for its activities, so-called powerhouse of
a cell.
Q. 12. What are the basic components of a cell?
Ans.Cell membrane, cytoplasm and nucleus are the basic components of a cell.
Q. 13. Is cell wall living or dead?
Q. 14. Is plasma membrane living or dead?
Q. 15. Name the control centre of the cell.
Q. 16. Which is the power house of the cell?
Q. 17. What is the common feature of all living organisms?
Ans.Living organisms have a well defined structure i.e., called as cell that functions with coordination
Q. 18. A hen's egg can be seen easily. Is it a cell or a group of cell.
Ans.The egg of a hen represents a single cell and it is big enough to be seen by the unaided eye.
Q. 19. What are cells?
Ans.Cells are complex structures but represent the basic structural and functional units of all living organisms.
Q. 20. Name the device that is used to magnify objects.
 21. What is the minimum size that can be seen with a microscope?
Ana.10-6 M.
Q. 22. Why cells could not be observed before 17th century?
Ans.Cells are too small to visible by naked eye. As there was no concept of microscope before 17th century, cells could not be observed.
Q. 23. Why Robert Hooke had to take thin slices of Cork?
Ans.Cork is a solid and its details' could not be observed by a primitive microscope developed by Hooke.
Q. 24. Where did Robert Hooke demonstrate cork slice?
Ans.Hooke demonstrated cork slice at the Royal Society of London.
Q. 25. Name two single celled organisms.
Ans.Paramecium, amoeba.
Q. 26. What is the diversity in the size of a cell?
Ans.A bacterial cell is as small as 0.1 micron (10-5 m) and an ostrich egg is as big as 170 x 10-3 m.
Q. 27. Name the organism with smallest cell size.
Ans.Bacteria mycoplasmas cell is as small as 0.1 micron.
Q. 28. Name the cells having branched structure.
Ans.Nerve cells
Q. 29. Which cell is observable with unaided eye?
Ans.Ostrich egg
Q. 30. Who observed first honey-comb like structure in cork, called cells? Give a sketch of Cork cells.
Ans.Robert Hooke

Fig. 8.3.Dead cork cells-Honey-comb structure
Q. 31. What is protoplasm? What gives it living nature?
Ans.Protoplasm is a fluid viscous substance of the cell and is surrounded by a membrane called plasma membrane. It constitutes different compounds such as water, carbohydrates, proteins, fats, nucleic acid and mineral salts. These compound in special combination provide living nature to protoplasm.
Q. 32. What differences or similarities you observe between living organism of a particular kind? Give an example.
Ans.Organisms of a particular kind differ in shape and size but are similar in structure and functions. For example, mouth of a bird, insect or elephant has the same function, i.e., consumption of food. Leaves of different plants differ in shape and size but all help in synthesis of food.
Q. 33. Describe the experiment conducted by Hooke on a Cork.
Ans.Robert Hooke tried to see the details of a cork under his own made microscope. Since, cork was a solid, he could not see anything special. He then made very thin slices and observed these under his microscope. He found that there were number of small spaces bounded by walls. He called each such bounded compartment as cell.
Q. 34. What is the difference between unicellular organisms and multicellular organisms?
Ans.In unicellular organisms, all the functions are carried out by a single cell whereas in multicellular organisms a large number of cells in coordination with each other perform various functions, so it is also said that in multicellulars.
Q. 35. Differentiate between organ and organelle.
Ans.Organ is group of tissues performing identical, specialized function, e.g., hand, nose etc. Organelle is a component of cell characterized by a specific function, e.g., mitochondria, vacuole etc.
Q. 36. What gives transport facility to cells?
Ans.Cells have projections over the cell surface outside the cell membrane. These are called cilia and flagella. Both these provides transport facility to cells.
Q. 37. Distinguish between plasma membrane and cell wall.
Plasma membraneCell walt
1. It is consisted of plasma protein and it is living
2. It is found in both plant and animal cells.
3. It is semi permeable.
4. It is soft and elastic.
1. It is made up of complex carbohydrate called cellulose and it is dead or non-living.
2. It is found in plant cells only.
3. It is permeable.
4. It is hard and rigid.
Q. 38. What is the significance of cell wall in a plant cell?
Ans.It performs the following functions in the plant cell:
        (i) It gives a definite shape to the cell.
       (ii) It provides rigidity and strength to the cell.
      (iii) It protects the inner cell organelles bounding the cell.
      (iv) It also withstand the osmotic pressure which is developed by cell contents.
Q. 39. What is the function of cell wall and plasma membrane?
Ans.Cell wall gives rigidity, shape and protection to plant cell.
         Plasma membraneallows only selected material to move in and out of the cell.
Q. 40. How do you differentiate protoplasm from cytoplasm?
Ans.Protoplasm is the liquid substance enclosed by cell membrane while cytoplasm is the liquid between the nucleus and plasma membrane. The organelles appear as particles in cytoplasm.
Q. 41. What advantage does amoeba derive by changing its shape?
Ans.The change in shape is due to formation of pseudopodia which facilitates movement and help in capturing food.
Q. 42. Is there any relation in between the size of the cell with the size of the body of animal or plant?
Ans. There is no relation. All most the cells size normal, but its number is related to the size of plants/animals.
Q. 43. Why plant cells need cell walls?
Ans. Plant cells need protection against variations in temperature, high wind speed, atmospheric moisture etc. They are exposed to these variations because they cannot move. That is why plant cells need cell walls.
Q. 44. Name the cell organelle/components which are known as
           (a) Control centre                                   (b) Power house of the cell
           (c) Kitchen of cell in plants                   (d) Site for protein synthesis
          (e) Store of genetic information             (f) Osmoregulationl food storage.
Ans.   (a) Nucleus            (b) Mitochondria     (c) Chloroplast
          (d) Ribosomes       (e) Chromosomes     (f) Vacuoles.
Q. 45. What is the diversity in the shape of a cell?
Ans.Cells are generally round and spherical. However, some cells vary from cuboidal to columnar. Even long and branched cells are also observed in some animals. (Fig. 8.4)

Fig. 8.4. Various types of typical cells showing different shapes
Q. 46. In order to compare a plant cell and an animal cell, complete the table 8.1.
            Table 8.1: Comparison of plant cell and animal cell
SI No.PartPlant cellAnimal cell
1.  Cell membranePresentPresent
2.  Cell wallPresentAbsent
3.  Nucleus  
4.  Nuclear membrane  
5.  Cytoplasm  
6.  Plastids  
7.  Vacuole  
SI No.PartPlant cellAnimal cell
1.Cell membranePresentPresent
2.Cell wallPresentAbsent
4.Nuclear membranePresentPresent
Q. 47. Write a note on the structure of cell.
Ans.Cell is the fundamental unit of a living organism.
       The cell is enclosed by an outer covering called ‘plasma membrane’ which is selectively permeable. Plant cells have an additional covering called ‘cell wall’.
       Inside the cell is the translucent viscous substance called ‘protoplasm’. The control centre of the cell is the nucleus which contains all the information necessary for the cell to function and to produce further cells for next generation.
       The protoplasm between nucleus and plasma membrane is ‘cytoplasm’ in which are embedded smaller particles called `organelles'. The organelle, mitochondria provides energy to the cell. In the cytoplasm there are droplets of substances dissolved in .water. They look empty spaces when viewed from a microscope. There are called vacuoles. In plant cells there is additional organelle called `chloroplast' which is the site for photosynthesis. (Fig. 8.5)
       For movement cells have surface projections called as the ‘cilia’ and ‘flagella’.

                                                              Fig. 8.5.A typical cell

Figure 8.5 shows sketches of human cheek cells.

                                       Fig. 8.6. human cheek cells


                                                           OBJECTIVE TYPE QUESTIONS

Q. 1. Fill in the blanks with appropriate words:
  1. Cells of a few cms are found in……….of animals or……….. of plants.
  2. The smallest cell is observed in............ .
  3. The shape of cells is generally………... .
  4. Red blood cell has a size of few………..
  5. The term cell was coined by………. .
  6. Basic structural unit of living organism is known as............ .
  7. Cell wall is present in…………. only.
  8. The largest cell is that of.............. .
Q. 2. Match the following items given in Column ‘A’ with that in Column ‘B’:
Column ‘A’Column ‘B’
(i) Epithelial cells
(ii) Muscle cells
(iii) Nerve cells
(iv) Egg cells
(v) Largest organelle
(vi) Cell wall
(a) Spindle shape
(b) Round
(c) Elongated
(d )Long branched
(e) Dead
(f) Plastids
Q. 3. State whether the statements given below are True or False:
  1. Coke is formed when coal is heated in ........ of air.
  2. Roots, stems, leaves and flowers are organs of plants.
  3. Plastids are found in animal cell only.
  4. Cytoplasm of the cell contains organelles.
  5. Is plasma membrane dead?
  6. Paramecium is a single called organism.
  7. Organ is a group of tissue performing identical, specialized function.
Q. 4. Choose the correct options in the following questions:
(i)   All organism consist of smaller part called
       (a) organs                                          (b) cell
       (c) cell wall                                       (d) organelle
(ii)  Which part of the cell contains organelles?
       (a) Protoplasm                                 (b) Nucleoplasm
       (c) Chromosomes                            (d) Cytoplasm
(iii) Which of the following is not a plastid?
       (a) Chloroplast                                 (b) Chromoplast
       (c) Leucoplast                                  (d) Ribosome
(iv) The color of chlorophyll pigment is
       (a) yellow                                          (b) green
       (c) red                                                (d) blue
(v)  Cell wall of plants is made up of
       (a) starch                                            (b) lignin
       (c) cellulose                                       (d) protein
(vi) Which of the following is not a unicellular organism?
       (a) WBC                                            (b) Paramecium           
       (c) Bacteria                                       (d) Amoeba
(vii) Mitosis is a
       (a) cell division                                 (b) cell death
       (c) cell elongation                               (d) cell wall
(viii) DNA stands for
         (a) Deoxy ribose nucleic acid                    (b) Deoxy ribonucleic acid
         (c) Dioxide nucleic acid                             (d) Dehydrogenate ribose nucleic acid
(ix) Which of the following is the site for energy production?
       (a) Mitochondria                                         (b) Nucleoplasm
       (c) Cytoplasm                                             (d) Nuclear membrane
(x)  The largest cell is that of
       (a) plant                                                      (b) ostrich egg
       (c) hen egg                                                 (d) human check
(xi) Which is the outermost layer of an animal cell?
       (a) Cell wall                                               (b) Cytoplasm
       (c) Plasma membrane                                (d) Protoplasm
(xii) What is known as the power house of the cell?
       (a) Ribosome                                              (b) Mitochondria
       (c) Vacuoles                                               (d) Nucleolus
(xiii) The Englishman, who discovered cell in 1665 was
       (a) Robert Cook                                        (b) Robert Frost
       (c) Robert Fleming                                   (d) Robert Hook
(xiv) Which is the control centre of the cell?
      (a) Nucleus                                                (b) Genes
      (c) Cell wall                                               (d) Golgi bodies
(xv) What is responsible for passing genetic characteristics from parents to off springs?
        (a) Chromosomes                                    (b) Genes
         (c) Nucleoplasm                                      (d) Nucleolus
Q. 1. Fill in the blanks:
         (i) muscles, fibres   (ii) mycoplasmas (iii) round      (iv) micrometer
        (v) Robert Hooke     (vi) cell               (vii) plants    (viii) ostrich egg.
Q. 2. Match the items under Column ‘A’ with Column ‘B’:
Column ‘A’Column ‘B’
(i) Epithelial cells
(ii) Muscle cells
(iii) Nerve cells
(iv) Egg cells
(v) Largest organelle
(vi) Cell wall
(c) Elongated
(a) Spindle shape
(d) Long branched
(b) Round
(e) Dead
(f) Plastids
Q. 3. True or False:
     i) True                 ii) False                iii) True                  iv) False            
    v) True                vi) False          
Q.4. Choose the correct option:
      (i) (b)                   (ii) (d)                  (iii) (a)                (iv) (b)                   (v) (c)
    (vi) (c)                 (vii) (a)                 (viii) (a)               (ix) (a)                   (x) (b)
    (xi) (c)                 (xii) (b)                 (xiii) (d)              (xiv) (a)                 (xv) (b).