Organization in the Living World – Questions and Answers
Question 1. What is a cell?
Answer.
A cell is the structural and functional unit of all living things.
Question 2. Name the scientist who discovered cell.
Answer.
Robert Hooke (1665).
Question 3. Who discovered nucleus?
Answer.
Robert Brown.
Question 4. Which cell organelle is called “power house” of the cell?
Answer.
Mitochondria.
Question 5. Cell theory was given by?
Answer.
Schleiden and Schwann.
Question 6. Who concluded that all cells arise from pre existing cells (Omni-cellular-e- cellula).
Answer.
Virchow (1855)
Question 7. What is nucleoid?
Answer.
Poorly developed nucleus without nuclear membrane is called nucleoid.
Question 8. Who coined the term protoplast?
Answer.
Purkinje(1839).
Question 9. Golgi apparatus was discovered by whom?
Answer.
Camillo Golgi.
Question 10. Name the cell organelles which are found in pi ant cells only.
Answer.
Cell wall and plastids.
Question 11. Which cell organelle is called “suicidal bag”.
Answer 11.
Lysosomes
Question 12. Name the cell organelles which have their own DNA and ribosomes.
Answer.
Mitochondria and Chloroplast.
Question 13. Which cell organelle is responsible for the synthesis of proteins and lipids?
Answer.
Endoplasmic reticulum.
Question 14. Full form of ATP is?
Answer.
Adenosine triphosphate.
Question 15. Which part of cell is responsible for inheritance of characters from parents to off springs?
Answer.
Nucleus.
Question 16. Name the phenomenon by which plant roots absorb water?
Answer.
Osmosis.
Question 17. Golgi bodies in plant cells are known as?
Answer.
Dictyosomes.
Question 18. In which cells, centrioles are found?
Answer.
Animal cells.
Question 19. What is the main difference between plant and animal cells?
Answer.
Cell wall is absent in animal cell.
Question 20. What is osmosis?
Answer.
It is the diffusion through selectively permeable membrane.
Question 21. Name the solutions used to stain cells?
Answer.
Iodine solution, safranin, methylene blue.
Question 22. What was the experimental material used by Robert Hooke during discovery of cell?
Answer.
Robert Hooke (1665) used a thin slice of cork which comes from the bark of Quercus suber tree.
Question 23. What are unicellular organisms?
Answer.
The organisms in which a single cell constitutes :he whole organism are called unicellular organisms, eg. Amoeba, Chlamydomonas, Paramoecium, bacteria etc.
Question 24. In the given figure some cells from human body -re drawn. Name them.
Answer.
(a) Sperm
(b) Nerve cell
Question 25. Why plasma membrane is present in both plant and animal cell?
Answer.
Plasma membrane bounds the protoplasm which has cell organelles. Boundation of cytoplasm is necessary for the existence of both plant and animal cells.
Question 26. What is the vacuole of unicellular organisms called and how they maintain water balance in the body?
Answer.
The vacuoles of unicellular organisms are called contractile vacuole and they maintain water balance in the body by expelling excess water from the cell.
Question 27. What main difference you can notice between cheek cells and onion peel cells under microscope?
Answer.
Onion peel cells show presence of cell wall while cheek cells show absence of cell wall.
Question 28. What is diffusion?
Answer.
Spontaneous movement of a substance from a region of high concentration to a region where its concentration is low is called diffusion.
Question 29. Define Osmosis.
Answer.
Osmosis is the passage of water from a region of high water concentration through a semi permeable membrane to a region of low water concentration.
Question 30. What will happen when dried raisins are (i) kept in plain water
(ii) kept in sugar solution?
Answer.
(i) Raisins gain water and swell due to endosmosis.
(ii) Raisins loose water and shrink due to exosmosis.
Question 31. What is plasmolysis?
Answer.
The phenomenon of shrinking of protoplasm of a cell due to loss of water when kept in hypertonic solution is called plasmolysis .
Question 32. How the genes are arranged in a cell?
Answer.
The nucleus of a cell contains chromosomes. Chromosomes contain DNA or Deoxyribonucleic acid molecules. The functional segments of DNA which carry hereditary information are called genes.
Question 33. Match the following —
Column A Column B
(a) Dividing cell (i) Chromatids
(b) Non-dividing cell (ii) Chromosomes.
Answer.
(a)-(ii),
(b)-(i).
Question 34. Mention important functions of smooth and rough endoplasmic reticulum.
Answer.
Smooth Endoplasmic Reticulum — Lipid synthesis
Rough Endoplasmic Reticulum — Protein synthesis
Question 35. The digestive enzymes of lysosomes are synthesized in which part of the cell?
Answer.
Rough endoplasmic reticulum synthesizes digestive enzymes present in lysosomes. After synthesis in RER these enzymes are carried by golgi apparatus to the lysosomes.
Question 36. What term would you use for the nucleus of bacteria and how it is organised?
Answer.
The term “ Nucleoid” is used for the poorly developed nucleus of bacteria. A nucleoid lacks nuclear membrane and has an undefined nuclear region containing nucleic acids.
.
Fig. A bacterial cell showing nucleoid.
Question 37. A prokaryotic cell lacks membrane-bound cell organelles like mitochondria, plastids etc. How the functions of these cell organelles are carried out by such cell.?
Answer.
Prokaryotic cells lack membrane-bound cell organelles. The functions of cell organelles carried out by poorly organised parts of cytoplasm. The infolds of cell membrane form mesosomes that carry out the function of mitochondria. In photosynthetic bacteria chlorophyll is associated with membranous vesicles instead of plastids.
Question 38. What is hypertonic solution? What is the fate of a plant cell in that solution.
Answer.
A solution which has lower concentration of water i.e., very concentrated solution is called hypertonic solution.
The plant cell will loose water by osmosis and shrink.
Question 39. What is the site of ATP production in Mitochondria?
Answer.
Mitochondria is a double layered membrane. The inner layer is folded and provides large surface area for ATP producing chemical reactions. Thus, the infoldings of membrane or cristae are the site of ATP production.
Question 40. What is “Membrane Biogenesis”.
Answer.
In a cell, rough endoplasmic reticulum has several ribosomes attached to its surface which are site of protein synthesis. Smooth endoplasmic reticulum is the site of lipid synthesis. The process of building cell membrane by these proteins and lipids is called membrane biogenesis.
Question 41. Site two major differences between a prokaryotic cell and an eukaryotic cell
Answer.
Question 42. What is major difference between a plant cell and animal cell?
Answer. Difference between a plant and animal cell
Question 43. What is the role of plastids in photosynthesis?
Answer.
Plastids contain green coloured pigment called chlorophyll. Green plants manufacture their own food in the presence of chlorophyll and sunlight by the process of photosynthesis. So, plastids are very important for plants.
Question 44. In a laboratory a student observed a slide under the microscope, the cells appeared as – How he could conclude whether it is a plant cell or animal cell ?
Answer.
Minute observation of cell reveals the presence of a cell wall outside cell membrane. A large vacuole, chloroplasts are also present in cytoplasm which are characteristic features of a plant cell. Thus it can be concluded that it is a plant cell. Match the following
Question 24. Match the following
Answer.
(a)-(ii),(b)-(iii);(c)-(iv),(d)-(i).