ADDITIONAL QUESTIONS AND ANSWER
1. What are plastids. Name the different types of plastids found in a plant cell.
Ans: Plastids are organelles found only in plants. They are:
(a) Chloroplast − Containing chlorophyll
(b) Chromoplast − Containing carotenoids and xanthophyll (coloured plastids)
(c) Leucoplast − White or colourless plastids
2. What is plasma membrane made up of.
Ans: Plasma membrane is made up of proteins and lipids.
3. What did Robert Hooke observed first in cork cell.
Ans: Robert Hooke observed that cork consists of box like compartments which formed a honeycomb structure.
4. Name the autonomous organelles in the cell.
Ans: Chloroplasts and Mitochondria are the autonomous organelles in the cells.
5. What does protoplasm refer to
Ans: Protoplasm refers to cytoplasm and nucleus.
6. Name two cells which keep changing their shape.
Ans: Amoeba and White Blood Cells.
7. Name the smallest cell and the longest cell in human body.
Ans: The smallest cell is the red blood cell or sperm cell in male. Longest cell is the nerve cell.
8. Name 3 features seen/present in almost every cell.
Ans: Three features seen/present in almost every cell are plasma membrane, nucleus and cytoplasm.
9. What is diffusion
Ans:: When gases like CO2, O2, move across the cell membrane, this process is called diffusion.
10. What is osmosis. How does it take place.
Ans:The movement of water molecules through a selectively permeable membrane is called osmosis. This takes place from high water concentration to low water concentration.
11. What is the full form of DNA
Ans: DNA full form is Deoxyribo Nucleic Acid.
12. What is the function of chromosome.
Ans:Chromosomes contain information for the inheritance of features from parents to next generation in the form of DNA molecules.
13. Name the organelles present in liver of animals for detoxifying many poisons and drugs.
Ans: In the liver of animal cells smooth endoplasmic reticulum helps in detoxifying many poisons and drugs.
14. What is the energy currency of the cell
Ans: ATP—Adenosine Tri Phosphate.
15. What is the function of ribosome
Ans: Ribosomes help in protein synthesis.
16. Where are genes located in the cell
Ans: Genes are located in the chromosomes in the nucleus of the cell.
17. Name the cell organelles that
(i) helps in packaging
(ii) helps in the transportation of material.
(iii) due to which leaves, flowers and fruits get their colour.
(iv) helps in the formation of lysosome.
(v) the cleansing organelle in the cell.
Ans: (i) Golgi apparatus,
(ii) Endoplasmic reticulum.
(iii) Chromoplast.
(iv) Golgi apparatus.
(v) Lysosome.
18. Name two cells with cell wall.
Ans: Two cells with cell wall.are onion cell (plant cell) and fungi.
19. Why does mitochondria have largely folded inner membrane.
Ans: Mitochondria is the site for cellular respiration and provides energy to the cell. The largely folded inner membrane provides the increased surface area for ATP generating chemical reactions.
20. Which organelle makes the digestive enzyme of lysosome.
Ans: Rough endoplasmic reticulum makes the digestive enzyme of lysosomes.
21. What are cisterns
Ans: The Golgi bodies consist of a system of membrane bound vesicles arranged in stacks called cisterns.
22. State two conditions required for osmosis.
Ans: (i) The difference in the concentration of water, one should have higher concentration than the other.
(ii) Semi-permeable membrane is also required through which water will flow.
23. What is plasmolysis
Ans: 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.
24. How does fungi and bacteria withstand much greater changes in the surrounding medium than animal cells
Ans: The cell wall present in fungi and bacteria permits these cells to withstand very dilute external medium without bursting.
25. Give the function of nuclear membrane.
Ans: The nuclear membrane present as outer covering in the nucleus allows the transfer of material inside and out of the nucleus to cytoplasm.
26. Name the cell-organelles that have their own DNA and ribosomes.
Ans: The cell organelles with their own DNA and ribosomes are mitochondria and plastids.
27. State the difference between smooth endoplasmic reticulum and rough endoplasmic reticulum.
Ans:
28. What is endocytosis.
Ans: The cell membranes flexibility allows the cell engulf in food and other material from its external environment. This process is known as endocytosis.
Eg., Amoeba acquires its food through such processes.
29. What is the function of vacuoles.
Ans: Vacuoles are storage sacs for solid or liquid content. In plant cells it provides turgidity and rigidity to the cell. In single-celled organisms vacuoles store food, e.g., Amoeba.
30. When we put raisins in water, why do they swell
Ans: Raisins are dry with less water inside, when they are kept in water, osmosis takes place, water flows through the cell wall, cell membrane of the raisins and therefore it swells.
31. Why are lysosomes called suicidal bags
Ans: Lysosomes contain digestive enzymes in it and helps in the cleaning of cell by digesting any foreign materials entering the cell, such as bacteria, food and old cell organelles.
When the lysosomes burst, the digestive enzyme digest its own cell. Hence it is called as suicidal bag.
32. What is nucleoid
Ans: The nuclear region in some cells are poorly defined due to the absence of a nuclear membrane, it contains only nucleic acid. This undefined nuclear region with nucleic acid in it is called nucleoid.
33. What is the role, of cell organelles in the cell.
Ans: Each kind of cell organelles performs a specific function such as making new material, clearing of the waste, transporting material, etc.
34. Label the figure and answer
(i) A – It is the packaging organelle
(ii) B – Provides energy
(iii) C – helps in the transport of material
(iv) D –Carries the information.
Ans: (i) A – Golgi body (ii) B – Mitochondria
(iii) C – Endoplasmic reticulum (iv) D – Nucleus
35. What is the function of nucleus in a cell
Ans: The nucleus plays a very important role in the reproduction of cells. It also helps the single cell to divide and form two new daughter cells.It plays an important role in determining how the cell will develop and what form it will exhibit at maturity, by directing the chemical activities of the cell.
36. What is the function of plastids
Ans: Plastids are present only in plant cells.
There are two types of plastids, chromoplasts (coloured plastids) and leucoplasts (white or colourless)
Chromoplast—Consists of coloured pigments and gives different colours to flowers, fruits and leaves. The green colour pigment present in leaf is called chlorophyll which helps in the photosynthesis and a plastid with chlorophyll is called chloroplast.
Leucoplast—It stores starch, oil and protein granules in it.
37. Explain the functions of Golgi bodies.
Ans: (1) The material synthesised near the ER is packaged and dispatched to various target inside and outside the cell through Golgi apparatus.
(2) It also stores, modifies and helps in the packaging of products in vesicles.
(3) In some cases, complex sugars may be made from simple sugars in it.
(4) It also helps in the formation of lysosomes.
38. What are ribosomes Where are they located in the cell
Ans: Ribosomes are spherical organelles present in the cell which are either freely distributed in the cytoplasm or may be attached to the endoplasmic reticulum.
39. What does Ribosome contain and what is their function
Ans: It consists of ribosomal RNA (Ribonucleic Acid) and proteins.
Functions of Ribosomes: It helps in the synthesis of proteins.
40. What is the difference in chromatin, chromosomes and genes.
Ans:
(1) Chromatin: It is a fine network of thread-like structure made up of DNA or RNA. It gets condense to form chromosomes.
(2) Chromosome: The chromosomes are made from chromatin material and are located in the cell.
(3) Genes are found in chromosomes.
41. Why do plant cells have more in number and big-sized vacuoles as compared to the animal cells
Ans: Plant cells attain turgidity and rigidity due to the more number of vacuoles as well as large-sized vacuoles help the plant cells to withstand the wear and tear, external environmental conditions.
42. What is membrane biogenesis
Ans: The endoplasmic reticulum helps in the manufacture of proteins and fat molecules or lipids which are important for the cell function. These proteins and lipids help in the building of the cell membrane. This process is known as membrane biogenesis
43. What are genes
Ans: Gene is a segment of DNA. They are located on chromosomes in linear fashions. One gene may perform one or more function. Genes are carrier of genetic codes.
44. Explain the following terms:
(a) Plasma membrane (b) Cytoplasm (c) Nucleus.
Ans:
(a) Plasma membrane:It is a thin membrane which controls the passage of materials in and out of the cell.
(b) Cytoplasm: It is transparent jelly-like thick substance present in the cell.
(c) Nucleus: It is a double-layered membrane structure which contains chromosomes
45. Name two cell organelles that have their own genetic material .
Ans: Two cell organelles that have their own genetic material are mitochondria and plastids .
46. Give a reason why plastids are able to make their own protein .
Ans: Plastids have their own DNA and hence can make their own protein .
47. List the constituents of plasma membrane .
Ans: Plasma membrane is made up of proteins and lipids .
48. The shape and size of cells are related to the specific function they perform . Justify given statement with a example .
Ans: Amoeba can change its shape to perform its functions . Nerve cell is elongated and has a typical shape to suit its function of transmission of signals . Thus , shape and size of cells are related to the specific function they perform .
49. What are the basic functions of a cell ?
Ans: The basic functions of a cell are respiration , nutrition , reproduction , etc . which are essential for survival .
50. ‘Every multicellular organism has arisen from a single cell’ . Justify the answer .
Ans: Cells divide to produce cells of their own kind . Thus , all cells come from pre-existing cells and hence every multicellular organism has arisen from a single cell .