NIOS Class 12 Biology Chapter 4 Solution – Cell Structure and Function
NIOS Class 12 Biology Solution Chapter 4 Cell Structure and Function . NIOS Class 12 Biology Chapter 4 Question Answers Download PDF. NIOS Class 12 Biology Notes.
NIOS Class 12 Biology Chapter 4 Solution
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Board |
NIOS |
| Class |
12th (Higher Secondary) |
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Subject |
Biology |
| Topic |
Question Answer, Solution, Notes |
INTEXT 4.1
1.) From where do new cells arise?
Ans:New cells arise from pre existing cells
2.) Name the scientists who proposed the ‘cell theory’.
Ans: . Schleiden and Schwann proposed the ‘cell theory’
3.) Name an organelle which a plant cell has but an animal cell does not.
Ans: Chloroplast is an organelle which a plant cell has but an animal cell does not
4.) Give two points of difference between a prokaryotic cell and a eukaryotic cell
Ans: Prokaryote have naked nucleus and no membrane bound cell organelles , while Eukaryote have distinct nucleus with a cell membrane and a membrane bound cell organelles present.
INTEXT 4.2
1.) Define diffusion and osmosis.
Ans: Diffusion is the movement of molecules from a place where they are more concentrated to a region where they are less concentrated.
Osmosis is in which Water molecules move through a semipermeable membrane from the area where they are concentrated more to the area where they are concentrated less.
2.) What does active transport mean?
Ans:Active transport means Molecules move against concentration gradients—regions of lower to greater concentration—by putting energy into their motion.
3.) Give one point of difference between phagocytosis and pinocytosis.
Ans: Intake of solid particles is called phagocytosis ans Intake of fluid droplets pinocytosis.
INTEXT 4.3
1.) What is a cell organelle?
Ans: . Cell organelle are the membrane bound bodies in the cytoplasm
2.) Name the chemical which provides energy trapped in its bonds to the cell.
Ans: ATP is the chemical which provides energy trapped in its bonds to the cell.
3.) Which part of the chloroplasts is the site of light reaction?
Ans: Grana is the part of the chloroplasts is the site of light reaction
4.) Name the sac like–structure which form the grana?
Ans: Thylakoids
5.) Why is mitochondrion called the “power house” of the cell?
Ans: Mitochondrion called the “power house” of the cell because energy in the form of ATP is generated and stored in mitochondria
6.) Which organelle contains enzymes for cellular respiration?
Ans: Mitochondria contains enzymes for cellular respiration
7.) State two similarities between mitochondria and chloroplasts.
Ans: Mitochondria and chloroplasts are semiautonomous of Life and both contain DNA or both contain ribosomes
8.) Which plastid imparts colour to flower petals?
Ans: Chromoplasts imparts colour to flower petals
9.) Which plastid is green in colour?
Ans: Chloroplast is green in colour .
10.) Why are mitochondria and chloroplast called semi-autonomous?
Ans: Although they possess their own DNA for the purpose of self-replication, they are unable to live independently outside of the cell or cytoplasm therefore mitochondria and chloroplast called semi-autonomous.
INTEXT 4.4
1.) Given below is a list of functions, relate them to their respective organelles:
(a) synthesis of some enzymes – Golgi body
(b) synthesis of steroids – ER
(c) storage of carbohydrates – amyloplasts
(d) Intracellular transport -ER
(e) Synthesis of proteins -Ribosomes
2.) Name the equivalent structure of Golgi body in plants. Mention two differences between their structures
Ans: Endoplasmic reticulum is the equivalent structure of Golgi body in plants.
(i) Endoplasmic reticulum is present d throughout the cytoplasm , while golgi body is present around the nucleus in animal. (ii) Endoplasmic reticulum contain ribosomes in there structure, while on golgi body it is absent.
3.) Mention any two advantages of the extensive network of endoplasmic reticulum
. (i) Internal framework
. (ii) transport of cellular substances
4.) What are the three places where ribosomes occur in a cell?
Ans: cytoplasm, ER and Nucleolusare three places where ribosomes occur in a cell
5.) Name the membrane system that connects the nuclear membrane with the cell membrane?
Ans: ER is the membrane system that connects the nuclear membrane with the cell membrane.
INTEXT 4.5
1.) Why are lysosomes called suicidal bags?
Ans: lysosomes called suicidal bags due to the fact that the lysosome can eat organelles from the same cell
2.) List the usefulness of intracellular digestion by lysosomes
Ans: (i) Help in defence by digesting germs, as in white blood cells.
(ii) Help in cleaning up the cell by digesting damaged material of the cell.
(iii) In plant cells, mature xylem cells lose all cellular contents by lysosome activity
3.) What is the function of peroxisomes in plant cells
Ans: Function of peroxisomes in plant cells is to metabolize fats.
INTEXT 4.6
1.) Why cannot the cell survive without the nucleus?
Ans: Cell cannot survive without the nucleus because it contains the genetic material, the nucleus is in charge of all cellular operations.
2.) Explain the following terms: (a) chromatin network.(b) chromosomes
Ans: (a) Chromatin network is a network, When chromosomes are not dividing, which occurs at early interphase or Go-stage,
(b) chromosomes are the genetic carriers of hereditary information
3.) What is the function of the nucleolus in the cell?
Ans: The nucleolus in the cell is the site of RNA synthesis
INTEXT 4.7
1.) What is the importance of water in a living cell.
Ans: (i) It is a universal solvent and most chemical reactions of the cell occur in aqueous medium (ii) It is a constituent of protoplasm
(iii) It is responsible for turgidity of cells.
2.) Which is the basic molecule in starch?
Ans: Glucose
3.) What is a peptide bond and where will you find it?
Ans: The molecular formula of peptide bond is –NHCO–. It is found between amino acids in a polypeptide
4.) Which is the most energy rich biomolecule in living organisms?
Ans: ATP is the most energy rich biomolecule in living organisms
5.) What are nucleotides?
Ans: A pentose sugar, a nitrogenous base, and phosphate are the three basic components of nucleic acids.
INTEXT 4.8
1.) Explain in one sentence
(i) Interphase – The interval between two successive cell divisions is termed interphase . It is the longest period in the cell cycle
(ii) Synthetic-phase – It is the phase where Synthesis of DNA occurs
(iii) Dividing-phase – – Mitosis in somatic cells or meiosis in the germ cells takes place.in this phase
2.) What is the full form of the following in the cell cycle?
(i) Gl -First growth phase
(ii) S- Synthetic phase
(iii) G2.- Second Growth phase
(iv) M-Phase- Mitosis/meiotic phase
INTEXT 4.9
1.) Name the stage of cell cycle during which chromatin material is duplicated.
Ans: The stage of cell cycle during which chromatin material is duplicated is S-shape of Interphase
2.) Is the number of chromosomes reduced in the daughter cells during mitosis? yes/no? .
Ans: No , the number of chromosomes is not reduced in the daughter cells during mitosis
3.) Name the stage in nuclear division described by each of the following sentences:
(i) disappearance of the nuclear membrane – Late Prophase;
(ii) The nuclear membrane and nucleolus reappear- Late Telophase;
(iii) The centromere divides and the chromatids move to opposite poles due to the shortening of spindle fibres .- Anaphase
(iv) The chromosomes arrange themselves at the equatorial plane of the spindle with the spindle fibres attached to the centromeres.- Metaphase
INTEXT 4.10
1.) Name the sub-stage of meiosis-I in which the :
(i)Homologous chromosomes pair.- zygotene (prophase I)
(ii) Tetrads are formed.- Pachytene
(iii) Homologous chromosomes begin to move away from each other.- Diplotene
2.) Sites of meiosis in flowering plants, are : Microspore/pollen mother cell in anthers and megaspore mother cell in the ovule.
3.) Rearrange the following stages of meiosis I in their proper sequence : zygotene, pachytene, leptotene, metaphase-I diakinesis, anaphase-I, telophase-I.
Ans: Leptotene, zygotene, pachytene, diplotene, diakinesis, metaphase I, telophase I.
4.) Mention two major points in which meiosis I differs from meiosis II
Ans: There is reduction in chromosome number to half in Meiosis-II and exchange of genetic material in meiosis I.
Also See: Previous Chapter No. 3 Question Answer
