CBSE Class 9 Science The Fundamental Unit of Life Sure Shot Questions Set 01

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ASSIGNMENT QUESTIONS SET - 1
CHAPTER - 5
THE FUNDAMENTAL UNIT OF LIFE

1. Define Cell [1 Mark]

Answer:
1. A cell is defined as the fundamental, structural, and functional unit of all living organisms.
2. It is often called the basic building block of life.

Teacher's Note:
a) Emphasize the keywords structural and functional unit.
b) Mention Robert Hooke as the discoverer for complete understanding.

2. What will happen to a cell if its nucleus is removed? [1 Mark]

Answer:
1. If the nucleus is removed, the cell will eventually die.
2. This occurs because the nucleus contains genetic material (DNA) that controls all cellular activities and metabolic processes.

Teacher's Note:
a) The nucleus acts as the control center of the cell.
b) Loss of DNA halts protein synthesis and cell regulation, leading to cell death.

3. Who proposed the Cell theory ? [1 Mark]

Answer:
1. The cell theory was proposed by Matthias Schleiden and Theodor Schwann.
2. Rudolf Virchow later expanded it by stating that all cells arise from pre-existing cells.

Teacher's Note:
a) Schleiden and Schwann formulated the initial biological concept.
b) Virchow added the third tenet regarding cell division.

4. What is Nucleoid ? [1 Mark]

Answer:
1. The undefined nuclear region in a prokaryotic cell containing only nucleic acids is called a nucleoid.
2. It lacks a surrounding nuclear membrane.

Teacher's Note:
a) It is characteristic of prokaryotes like bacteria.
b) Distinguish clearly between a true nucleus and a nucleoid.

5. Fill in the blanks:- [5 Marks]
(a) New cells are formed from ______________.
(b) Movement of water molecules from their higher concentration to their lower concentration through a semi- permeable membrane is called ______________.
(c) The functional components of cell are ______________, ______________& ______________.
(d) Protoplasm has two parts- ______________ & ______________.
(e) Nucleus, mitochondria & plastids have their own ___________ & ____________.
(f) The shrinkage or contraction of the contents of the cell away from the cell wall is known as ______________.
(g) The process by which Amoeba can engulf a food particle is ______________.
(h) ______________ is the manufacture of lipids required for making cell membrane.
(i) A cell that lacks nuclear membrane is called a prokaryotic cell & the nuclear region is called ______________.
(j) Movement of materials in & out of the cell takes place by ______________ & ______________.

Answer:
(a) pre-existing cells
(b) osmosis
(c) cell membrane, cytoplasm, nucleus
(d) cytoplasm, nucleus
(e) DNA, ribosomes (or RNA)
(f) plasmolysis
(g) endocytosis (or phagocytosis)
(h) Smooth Endoplasmic Reticulum (SER)
(i) nucleoid
(j) diffusion, osmosis

Teacher's Note:
a) Each blank tests a fundamental definition from cell biology.
b) Ensure students write complete statements or exact terms for scoring.

6. Identifiy and name the following cell structures: [2 Marks]
a) The undefined nuclear region of Prokaryotic cell.
b) Site of energy release inside the cell.

Answer:
1. (a) Nucleoid
2. (b) Mitochondria

Teacher's Note:
a) Mitochondria are known as the powerhouse of the cell.
b) The nucleoid contains unorganized genetic material without a membrane.

7. Name the kind of plastid which is important for photosynthesis in leaves of the plants. [1 Mark]

Answer:
1. Chloroplast.

Teacher's Note:
a) Chloroplasts contain the green pigment chlorophyll.
b) Chlorophyll is essential for trapping solar energy during photosynthesis.

8. Name the two components of chromosomes. [1 Mark]

Answer:
1. DNA (Deoxyribonucleic acid) and proteins.

Teacher's Note:
a) Chromosomes carry hereditary information from parents to offspring.
b) Proteins provide structural support to the DNA molecule.

9. When does the chromatin network separate out to form chromosomes? [1 Mark]

Answer:
1. The chromatin network condenses and separates out to form chromosomes just before the cell divides.

Teacher's Note:
a) This occurs during the prophase stage of cell division.
b) Chromatin exists as thin entangled threads during non-dividing phases.

10. Name the cell organelle that detoxifies poisons and drugs. [1 Mark]

Answer:
1. Smooth Endoplasmic Reticulum (SER).

Teacher's Note:
a) SER plays a crucial role in detoxifying many poisons and drugs in liver cells.
b) It contrasts with Rough ER which is studded with ribosomes.

11. Name the cell organelle that is associated with protein synthesis. [1 Mark]

Answer:
1. Ribosome.

Teacher's Note:
a) Ribosomes are attached to the Rough Endoplasmic Reticulum or float freely in the cytoplasm.
b) They are known as the protein factories of the cell.

12. Name a cell which changes its shape. [1 Mark]

Answer:
1. Amoeba (or White Blood Cells / WBCs).

Teacher's Note:
a) Amoeba uses pseudopodia to change shape and move.
b) WBCs in human blood can also change shape to engulf pathogens.

13. Name the functional unit of DNA that carries genetic informations. [1 Mark]

Answer:
1. Gene.

Answer:
1. Deoxyribonucleic Acid.

Teacher's Note:
a) Spelling of Deoxyribonucleic must be exact for full credit.
b) It is the primary carrier of genetic information in living organisms.

15. State the primary functions of plasma membrane. [2 Marks]

Answer:
1. It acts as a mechanical barrier protecting the internal contents of the cell.
2. It regulates the movement of substances in and out of the cell through selective permeability.

Teacher's Note:
a) Selective permeability allows essential nutrients to enter and wastes to leave.
b) It is composed of lipids and proteins.

16. Name a cell that lacks cell wall [1 Mark]

Answer:
1. Animal cells lack a cell wall.
2. Example: Human red blood cell or any animal cell.

Teacher's Note:
a) Animal cells are bounded only by a cell membrane.
b) Plant cells possess a rigid outer cell wall made of cellulose.

17. Name the main constituent substance present in plant cell wall. [1 Mark]

Answer:
1. Cellulose is the main constituent substance present in plant cell walls.
2. It provides structural strength to plants.

Teacher's Note:
a) Cellulose is a complex carbohydrate composed of glucose units.
b) It makes the plant cell wall tough and rigid.

18. Name the cell which is responsible for intracellular transport. [1 Mark]

Answer:
1. Endoplasmic Reticulum (ER) is responsible for intracellular transport.
2. It acts as a channel for transporting materials between various regions of the cytoplasm.

Teacher's Note:
a) The endoplasmic reticulum forms a network of membrane tubules.
b) It transports proteins and lipids inside the cell.

19. Name the Reticulum which has ribosome’s attached to it . [1 Mark]

Answer:
1. Rough Endoplasmic Reticulum (RER) has ribosomes attached to its surface.
2. These ribosomes are actively involved in protein synthesis.

Teacher's Note:
a) The outer surface of RER appears rough due to ribosomes.
b) Smooth Endoplasmic Reticulum lacks ribosomes and synthesizes lipids.

20. Name a cell that does not have a nucleus, what are they called? [1 Mark]

Answer:
1. Mammalian red blood cells and plant sieve tube cells do not have a nucleus.
2. Organisms whose cells lack a true membrane-bound nucleus are called prokaryotes.

Teacher's Note:
a) Prokaryotic cells lack a defined nuclear membrane.
b) Their nuclear region is poorly defined and known as a nucleoid.

21. The largest cell in the human body is - [1 Mark]
(A) Nerve cell
(B) Muscle cell
(C) Liver cell
(D) Kidney cell

Answer: (A) Nerve cell

1. Nerve cells or neurons are the longest and largest cells in the human body.
2. They are specialized for transmitting nerve impulses.
3. Hence, the correct option is (A).

Teacher's Note:
a) Nerve cells can be up to a meter long.
b) Ostrich egg is the largest isolated single cell overall, but nerve cell is the largest in humans.

22. The barrier between the protoplasm and the other environment in an animal cells - [1 Mark]
(A) Cell wall
(B) Nuclear membrane
(C) Tonoplast
(D) Plasma membrane

Answer: (D) Plasma membrane

1. Plasma membrane is the outermost covering of animal cells.
2. It separates the contents of the cell from its external environment.
3. Hence, the correct option is (D).

Teacher's Note:
a) Plasma membrane is selectively permeable.
b) Animal cells do not have a cell wall.

23. The term ‘Cell’ was given by - [1 Mark]
(A) Leeuwenhoek
(B) Robert hooke
(C) Flemming
(D) Robert Brown

Answer: (B) Robert hooke

1. Robert Hooke discovered cells in 1665 using a self-designed microscope.
2. He observed cork slices and coined the term cell.
3. Hence, the correct option is (B).

Teacher's Note:
a) The word cell is derived from a Latin word meaning a little room.
b) Robert Leeuwenhoek discovered free-living cells in pond water.

24. Who proposed the cell theory? - [1 Mark]
(A) Schleiden and Schwann
(B) Watson and Crick
(C) Darwin and Wallace
(D) Mendel and Morgan

Answer: (A) Schleiden and Schwann

1. Schleiden and Schwann formulated the cell theory.
2. Virchow later expanded it by stating that all cells arise from pre-existing cells.
3. Hence, the correct option is (A).

Teacher's Note:
a) Cell theory states that all plants and animals are composed of cells.
b) It also states that the cell is the basic unit of life.

25. A plant cell differs from an animal cell in the absence of - [1 Mark]
(A) Endoplasmic Reticulum
(B) Mitochondria
(C) Ribosome
(D) Centrioles

Answer: (D) Centrioles

1. Centrioles are generally present in animal cells and absent in most plant cells.
2. Plant cells contain cell walls and plastids which are absent in animal cells.
3. Hence, the correct option is (D).

Teacher's Note:
a) Centrioles help in cell division in animal cells.
b) Plant cells have spindle fibers formed without centrioles.

26. Centrosome is found in - [1 Mark]
(A) Cytoplasm
(B) Nucleus
(C) Chromosomes
(D) Nucleolus

Answer: (A) Cytoplasm

1. Centrosome is an organelle found near the nucleus in the cytoplasm.
2. It contains centrioles and plays a role in animal cell division.
3. Hence, the correct option is (A).

Teacher's Note:
a) Cytoplasm is the fluid content inside the plasma membrane.
b) Organelles like mitochondria and centrosomes are suspended in it.

27. The power house of a cell is - [1 Mark]
(A) Chloroplast
(B) Mitochondrion
(C) Golgi apparatus
(D) Nucleolus

Answer: (B) Mitochondrion

1. Mitochondria generate chemical energy needed for cellular biochemical reactions.
2. The energy is stored in the form of ATP molecules, earning them the title of powerhouse.
3. Hence, the correct option is (B).

Teacher's Note:
a) ATP stands for Adenosine triphosphate.
b) Mitochondria have their own DNA and ribosomes.

28. Within a cell the site of respiration (oxidation) is the - [1 Mark]
(A) Ribosome
(B) Golgi apparatus
(C) Mitochondrion
(D) Endoplasmic Reticulum

Answer: (C) Mitochondrion

1. Cellular respiration and oxidation of food occur inside mitochondria.
2. This process releases energy for various cellular activities.
3. Hence, the correct option is (C).

Teacher's Note:
a) Mitochondria contain enzymes necessary for cellular respiration.
b) They have a double-membrane structure.

29. Which is called ‘Suicidal Bag’? [1 Mark]
(A) Centrosome
(B) Lysosome
(C) Mesosome
(D) Chromosome

Answer: (B) Lysosome

1. Lysosomes contain powerful digestive enzymes capable of breaking down organic material.
2. When the cell gets damaged, lysosomes may burst and digest their own cell, hence called suicidal bags.
3. Hence, the correct option is (B).

Teacher's Note:
a) Lysosomes are waste disposal systems of the cell.
b) They are membrane-bound sacs filled with digestive enzymes.

30. Ribosomes are the center for - [1 Mark]
(A) Respiration
(B) Photosynthesis
(C) Protein synthesis
(D) Fat synthesis

Answer: (C) Protein synthesis

1. Ribosomes are cellular structures responsible for assembling proteins.
2. They translate genetic instructions into polypeptide chains.
3. Hence, the correct option is (C).

Teacher's Note:
a) Ribosomes are found attached to the rough endoplasmic reticulum or free in cytoplasm.
b) They are non-membrane bound organelles found in all cells.

31. Double membrane is absent in - [1 Mark]
(a) Mitochondrion
(b) Chloroplast
(c) Nucleus
(d) Lysosome

Answer: (d) Lysosome

1. Lysosomes are single membrane-bound organelles containing digestive enzymes.
2. Mitochondria, chloroplasts, and nuclei possess double membrane envelopes.
3. Hence, the correct option is (d).

Teacher's Note:
a) Lysosomes act as the waste disposal system of the cell.
b) Double membranes provide compartmentalization for complex metabolic reactions.

32. Cell organelle found only in Plant is - [1 Mark]
(a) Golgi apparatus
(b) Mitochondria
(c) Plastids
(d) Ribosomes

Answer: (c) Plastids

1. Plastids are plant-specific organelles involved in photosynthesis and storage.
2. Golgi apparatus, mitochondria, and ribosomes are present in both plant and animal cells.
3. Hence, the correct option is (c).

Teacher's Note:
a) Chloroplasts are a common type of plastid containing chlorophyll.
b) Animal cells lack cell walls and plastids entirely.

33. Organisms lacking nucleus and membrane bound organelle are - [1 Mark]
(a) Diploids
(b) Prokaryotes
(c) Haploids
(d) Eukaryotes

Answer: (b) Prokaryotes

1. Prokaryotic cells lack a defined nucleus and membrane-bound organelles.
2. Eukaryotes possess a well-organized nucleus and membrane-bound organelles.
3. Hence, the correct option is (b).

Teacher's Note:
a) Bacteria and blue-green algae are classic examples of prokaryotes.
b) Diploid and haploid refer to chromosome set numbers, not cell types.

34. Animal cell is limited by - [1 Mark]
(a) Plasma membrane
(b) Shell membrane
(c) Cell wall
(d) Basement membrane

Answer: (a) Plasma membrane

1. The plasma membrane forms the outer boundary of animal cells.
2. Plant cells additionally possess an outer rigid cell wall.
3. Hence, the correct option is (a).

Teacher's Note:
a) The plasma membrane is selectively permeable, regulating entry and exit of substances.
b) It is composed of lipids and proteins.

35. The network of Endoplasmic Reticulum is present in the - [1 Mark]
(a) Nucleus
(b) Nucleolus
(c) Cytoplasm
(d) Chromosomes

Answer: (c) Cytoplasm

1. Endoplasmic Reticulum (ER) forms a network of membrane tubules distributed in the cytoplasm.
2. It is continuous with the outer nuclear membrane but located in the cytoplasm.
3. Hence, the correct option is (c).

Teacher's Note:
a) Rough ER has ribosomes attached, while smooth ER lacks them.
b) ER plays a crucial role in protein and lipid synthesis.

36. Lysosome are reservoirs of - [1 Mark]
(a) Fat
(b) RNA
(c) Secretary Glycoprotein
(d) Hydrolytic Enzymes

Answer: (d) Hydrolytic Enzymes

1. Lysosomes store powerful digestive enzymes capable of breaking down organic material.
2. These hydrolytic enzymes are synthesized by rough ER and processed in the Golgi apparatus.
3. Hence, the correct option is (d).

Teacher's Note:
a) They are often called suicide bags due to their role in autolysis.
b) Active in acidic pH conditions maintained inside the organelle.

37. The membrane surrounding the vacuole of a plant cell is called - [1 Mark]
(a) Tonoplast
(b) Plasma membrane
(c) Nuclear membrane
(d) Cell wall

Answer: (a) Tonoplast

1. The single membrane surrounding the plant vacuole is known as the tonoplast.
2. It helps in actively transporting ions against concentration gradients into the vacuole.
3. Hence, the correct option is (a).

Teacher's Note:
a) Vacuoles provide turgidity and rigidity to plant cells.
b) Plant vacuoles can occupy up to 90 percent of cell volume.

38. Cell secretion is done by - [1 Mark]
(a) Plastids
(b) ER
(c) Golgi apparatus
(d) Nucleolus

Answer: (c) Golgi apparatus

1. The Golgi apparatus modifies, packages, and secretes cellular products.
2. Secretory vesicles pinch off from the Golgi to release contents outside the cell.
3. Hence, the correct option is (c).

Teacher's Note:
a) Camillo Golgi discovered this organelle using a silver impregnation method.
b) It also forms lysosomes and peroxisomes.

39. Centrioles are associated with - [1 Mark]
(a) DNA synthesis
(b) Reproduction
(c) Spindle formation
(d) Respiration

Answer: (c) Spindle formation

1. Centrioles form the spindle apparatus during cell division in animal cells.
2. They help in organizing microtubules during mitosis and meiosis.
3. Hence, the correct option is (c).

Teacher's Note:
a) Centrioles are cylindrical structures made of microtubules.
b) They typically occur in pairs near the nucleus in animal cells.

40. Main difference between animal cell and plant cell is - [1 Mark]
(a) Chromosome
(b) Ribosome
(c) Lysosome
(d) Endoplasmic Reticulum

Answer: (c) Lysosome

1. Lysosomes are commonly found in animal cells and are rare or absent in plant cells.
2. Other options like ribosomes, chromosomes, and ER are common to both cell types.
3. Hence, the correct option is (c).

Teacher's Note:
a) Plant cells have cell walls and large central vacuoles instead.
b) Watch out for organelle distribution differences in comparative questions.

41. Animal cell lacking nuclei would also lack in - [1 Mark]
(a) Chromosome
(b) Ribosome
(c) Lysosome
(d) Endoplasmic Reticulum

Answer: (a) Chromosome

1. Chromosomes are housed inside the nucleus, carrying genetic information.
2. Anucleate cells cannot contain chromosomes.
3. Hence, the correct option is (a).

Teacher's Note:
a) Mammalian red blood cells lose their nuclei and chromosomes upon maturation.
b) Cytoplasmic organelles can still briefly persist without a nucleus.

42. Plasmolysis occurs due to - [1 Mark]
(a) Absorption
(b) Endosmosis
(c) Exosmosis
(d) Diffusion

Answer: (d) Exosmosis

1. Plasmolysis is the shrinkage of plant protoplasm away from the cell wall due to water loss.
2. This water loss happens through exosmosis when placed in a hypertonic solution.
3. Hence, the correct option is (c).

Teacher's Note:
a) Hypertonic solutions have higher solute concentration outside the cell.
b) Endosmosis causes swelling or turgidity in hypotonic solutions.

43. A plant cell becomes turgid due to - [1 Mark]
(A) Plasmolysis
(B) Exosmosis
(C) Endosmosis
(D) Electrolysis

Answer: (C) Endosmosis

1. Endosmosis is the inward movement of water into a cell when placed in a hypotonic solution.
2. Water enters the plant cell, making it swell and become turgid against the cell wall.
3. Hence, the correct option is (C).

Teacher's Note:
a) Turgidity provides rigidity and mechanical support to plant cells.
b) Plasmolysis is the opposite process where water moves out, causing shrinkage.

44. Solute concentration is higher in the external solution - [1 Mark]
(A) Hypotonic
(B) Isotonic
(C) Hypertonic
(D) None of the above

Answer: (C) Hypertonic

1. A hypertonic solution has a higher solute concentration compared to the cytoplasm of the cell.
2. This creates a concentration gradient causing water to flow out of the cell.
3. Hence, the correct option is (C).

Teacher's Note:
a) In a hypotonic solution, the external solute concentration is lower.
b) Isotonic solutions have equal solute concentrations inside and outside the cell.

45. A cell placed in hypertonic solution will - [1 Mark]
(A) Shrink
(B) Show Plasmolysis
(C) Swell up
(D) No change in shape or size

Answer: (A) Shrink

1. In a hypertonic solution, water moves out of the cell due to exosmosis.
2. Loss of water causes the cell to shrink or lose its turgidity.
3. Hence, the correct option is (A).

Teacher's Note:
a) Plant cells in hypertonic solutions specifically undergo plasmolysis where the plasma membrane pulls away from the cell wall.
b) Animal cells simply shrink or crenate.

46. The radiant energy of sunlight is converted to chemical energy and is stored as - [1 Mark]
(A) AMP
(B) ADP
(C) ATP
(D) APP

Answer: (C) ATP

1. During photosynthesis, chloroplasts trap solar energy and convert it into chemical energy.
2. This energy is stored in the form of Adenosine Triphosphate (ATP) molecules.
3. Hence, the correct option is (C).

Teacher's Note:
a) ATP is universally known as the energy currency of the cell.
b) Mitochondria also synthesize ATP during cellular respiration.

47. Which of the following organelle does not have membrane? [1 Mark]
(A) Ribosome
(B) Nucleus
(C) Chloroplast
(D) Mitochondria

Answer: (A) Ribosome

1. Ribosomes are non-membrane-bound organelles found in both prokaryotic and eukaryotic cells.
2. Nucleus, chloroplasts, and mitochondria are all bounded by double membranes.
3. Hence, the correct option is (A).

Teacher's Note:
a) Ribosomes are primarily responsible for protein synthesis in the cell.
b) Centrosomes are another example of non-membrane-bound organelles in animal cells.

48. Root hair absorbs water from soil through - [1 Mark]
(A) Osmosis
(B) Active transport
(C) Diffusion
(D) Endocytosis

Answer: (A) Osmosis

1. The soil water concentration is higher than the cell sap inside root hair cells.
2. Water moves across the semi-permeable plasma membrane of root hairs via osmosis.
3. Hence, the correct option is (A).

Teacher's Note:
a) Osmosis is a special case of diffusion involving the movement of water across a selectively permeable membrane.
b) Mineral ions are often absorbed by active transport.

49. The number of lenses in compound light microscope is - [1 Mark]
(A) 2
(B) 3
(C) 4
(D) 1

Answer: (A) 2

1. A standard compound light microscope uses a combination of at least two sets of lenses.
2. These are the ocular lens (eyepiece) and the objective lens.
3. Hence, the correct option is (A).

Teacher's Note:
a) The term compound refers to the use of multiple lens systems to magnify specimens.
b) Total magnification is calculated by multiplying the magnification power of the ocular lens by the objective lens.

50. The history of the cell began in 1665 with the publication of Micrographia in London by - [1 Mark]
(A) Robert Hooke
(B) Robert Brown
(C) Strasburger
(D) Dujardin

Answer: (A) Robert Hooke

1. Robert Hooke observed thin slices of cork under a self-designed microscope in 1665.
2. He coined the term 'cell' and published his findings in his book Micrographia.
3. Hence, the correct option is (A).

Teacher's Note:
a) Robert Brown later discovered the cell nucleus in 1831.
b) Leeuwenhoek discovered free-living cells in pond water for the first time.

51. Cell inclusions are - [1 Mark]
(A) Non-living materials present in the cytoplasm
(B) Another name of cell organelle
(C) Cytoskeletal framework of cell
(D) Combined name for cell wall and plasma membrane

Answer: (A) Non-living materials present in the cytoplasm

1. Cell inclusions are non-living, cytoplasmic or nucleoplasmic entities made up of reserve nutrients or pigments.
2. They do not possess metabolic activity of their own.
3. Hence, the correct option is (A).

Teacher's Note:
a) Examples include starch grains, glycogen granules, and fat droplets.
b) They are distinct from living functional organelles.

52. Which cell organelle is not bounded by a membrane - [1 Mark]
(A) Ribosome
(B) Lysosome
(C) ER
(D) Nucleus

Answer: (A) Ribosome

1. Ribosomes are ribonucleoprotein particles lacking any surrounding membrane.
2. Lysosomes, endoplasmic reticulum (ER), and nucleus are all membrane-bound structures.
3. Hence, the correct option is (A).

Teacher's Note:
a) This question tests the structural classification of cell organelles.
b) Lack of a membrane allows ribosomes to exist freely in the cytoplasm as well as attached to the rough ER.

53. Which of the following cellular part possess a double membrane? [1 Mark]
(A) Nucleus
(B) Chloroplast
(C) Mitochondrion
(D) All of the above

Answer: (D) All of the above

1. The nucleus is bounded by a double-membraned nuclear envelope.
2. Both chloroplasts and mitochondria possess outer and inner double-membrane systems.
3. Hence, the correct option is (D).

Teacher's Note:
a) Mitochondria and chloroplasts are semi-autonomous organelles containing their own DNA and ribosomes.
b) Double membranes help compartmentalize specific metabolic reactions efficiently.

54. Cristae and Oxysomes are associated with - [1 Mark]
(A) Mitochondria
(B) Plastids
(C) Golgi apparatus
(D) Plasma membrane

Answer: (A) Mitochondria

1. Cristae are inner membrane folds of mitochondria.
2. Oxysomes are F0-F1 particles located on the cristae involved in ATP synthesis.
3. Hence, the correct option is (A).

Teacher's Note:
a) Cristae increase the surface area for biochemical reactions.
b) Mitochondria are known as the powerhouse of the cell.

55. Karyotheca is another name of - [1 Mark]
(A) Nuclear envelope
(B) Nucleus
(C) Nuclear pores
(D) Nucleolus

Answer: (A) Nuclear envelope

1. Karyotheca is the scientific term for the double membrane surrounding the nucleus.
2. It separates the nuclear contents from the cytoplasm.
3. Hence, the correct option is (A).

Teacher's Note:
a) 'Karyo' means nucleus and 'theca' means covering or envelope.
b) It contains pores for material exchange.

56. Cell organelle that acts as supporting skeletal framework of the cell is - [1 Mark]
(A) Golgi apparatus
(B) Nucleus
(C) Mitochondria
(D) ER

Answer: (D) ER

1. The endoplasmic reticulum forms a network of membranous tubules.
2. It serves as a channel for the transport of materials and provides a skeletal framework.
3. Hence, the correct option is (D).

Teacher's Note:
a) ER stands for Endoplasmic Reticulum.
b) It can be rough or smooth depending on the presence of ribosomes.

57. Plastids are present in - [1 Mark]
(A) Animal cell only
(B) Plant cells only
(C) Both animal cells and Plant cells
(D) Neither animal nor plant cell

Answer: (B) Plant cells only

1. Plastids are characteristic organelles found exclusively in plant cells and Euglenoids.
2. They contain pigments such as chlorophyll for photosynthesis.
3. Hence, the correct option is (B).

Teacher's Note:
a) Animal cells lack plastids as they do not perform photosynthesis.
b) Chloroplasts, chromoplasts, and leucoplasts are types of plastids.

58. Cell wall of plant is chiefly composed of - [1 Mark]
(A) Hemicellulose
(B) Cellulose
(C) Phospholipids
(D) Proteins

Answer: (B) Cellulose

1. Plant cell walls provide structural strength and rigidity.
2. They are mainly composed of cellulose microfibrils.
3. Hence, the correct option is (B).

Teacher's Note:
a) Cellulose is a complex carbohydrate and polymer of glucose.
b) Fungal cell walls are made of chitin instead of cellulose.

59. Intercellular connections of plant cells are called - [1 Mark]
(A) Middle lamella
(B) Micro fibrils
(C) Matrix
(D) Plasmodesmata

Answer: (D) Plasmodesmata

1. Plasmodesmata are microscopic channels which traverse the cell walls of plant cells.
2. They enable transport and communication between individual plant cells.
3. Hence, the correct option is (D).

Teacher's Note:
a) Middle lamella is a cementing layer between adjacent cells.
b) Plasmodesmata act as cytoplasmic bridges.

60. Genes are located on the - [1 Mark]
(A) Chromosomes
(B) Nucleolus
(C) Nuclear membrane
(D) Plasma membrane

Answer: (A) Chromosomes

1. Genes are hereditary units made of DNA segments.
2. They are linearly arranged on chromosomes inside the nucleus.
3. Hence, the correct option is (A).

Teacher's Note:
a) Chromosomes are composed of DNA and proteins.
b) They transfer genetic information from parents to offspring.

61. Chromatin consists of - [1 Mark]
(A) RNA
(B) DNA
(C) RNA and histones (proteins)
(D) DNA and histones (proteins)

Answer: (D) DNA and histones (proteins)

1. Chromatin material is the uncoiled form of chromosomes.
2. It consists of DNA threads wound around basic histone proteins.
3. Hence, the correct option is (D).

Teacher's Note:
a) Histones help in the packaging of long DNA molecules.
b) During cell division, chromatin condenses into distinct chromosomes.

62. Different types of chromosomes can be recognized by the positions of the following separating the two arms - [1 Mark]
(A) Centromere
(B) Genes
(C) Spindle
(D) Nucleus

Answer: (A) Centromere

1. The centromere is a constricted region holding sister chromatids together.
2. Its position determines chromosome shapes like metacentric, acrocentric, or telocentric.
3. Hence, the correct option is (A).

Teacher's Note:
a) Spindle fibers attach to the centromere during cell division.
b) Genes are located along the arms, not separating them.

63. Name of the process that requires energy provided by ATP - [1 Mark]
(A) Diffusion
(B) Osmosis
(C) Active transport
(D) Plasmolysis

Answer: (C) Active transport

1. Active transport moves molecules across cell membranes against a concentration gradient.
2. This process requires metabolic energy in the form of ATP.
3. Hence, the correct option is (C).

Teacher's Note:
a) Diffusion and osmosis are passive transport processes requiring no ATP.
b) Sodium-potassium pumps are classic examples of active transport.

64. What is the advantage of multicellularity over unicellularity? [2 Marks]

Answer:
1. Division of labor: Different groups of cells are specialized to perform different complex body functions efficiently.
2. Higher survival rate: Multicellular organisms can survive the death of individual cells because tissues and organs can regenerate or replace them.

Teacher's Note:
a) Unicellular organisms have a single cell performing all life processes.
b) Multicellularity allows greater size, complexity, and efficiency.

65. What are the chromosomes made up of? [2 Marks]

Answer:
1. Chromosomes are primarily composed of Deoxyribonucleic Acid (DNA).
2. They also contain structural proteins called histones that help pack and organize the DNA molecules.

Teacher's Note:
a) DNA carries the genetic blueprint of living organisms.
b) Histone proteins provide structural support for the DNA thread.

66. A cell placed in a solution swells up. What kind of solution is it? Why does it happen? [2 Marks]

Answer:
1. The solution is a hypotonic solution.
2. It happens because the concentration of water molecules in the surrounding solution is higher than that inside the cell, causing water to enter the cell by osmosis.

Teacher's Note:
a) A hypotonic solution has a lower solute concentration than the cell interior.
b) Water moves across the plasma membrane from a region of higher water concentration to a region of lower water concentration.

67. Why are lysosomes known as “suicidal bags”? [2 Marks]

Answer:
1. Lysosomes contain powerful digestive enzymes capable of breaking down all organic material.
2. When the cell gets damaged or bursts during cellular disturbance, lysosomes release these digestive enzymes to digest their own cell, hence they are called suicidal bags.

Teacher's Note:
a) Lysosomes are membrane-bound sacs filled with digestive enzymes made by RER.
b) They perform intracellular digestion of foreign materials and worn-out cell organelles.

68. Why is the nucleus so significant in a cell? [2 Marks]

Answer:
1. The nucleus contains chromosomes that bear DNA, which holds all the genetic information required for cellular activities, growth, and reproduction.
2. It acts as the control center of the cell, directing all metabolic processes and protein synthesis.

Teacher's Note:
a) The nucleus is bounded by a double-layered membrane called the nuclear membrane.
b) It plays a central role in cellular reproduction by transmitting hereditary traits.

69. Differentiate between plant and animal cells. [3 Marks]

Answer:

Teacher's Note:
a) Plant cells have a rigid outer boundary called the cell wall.
b) Animal cells possess centrosomes and centrioles which are absent in most plant cells.
c) Always use a table format for differentiation questions to secure full marks.

70. Give the major functions of the following cell organelles- [2 Marks]

Answer:
1. Mitochondria: Generates chemical energy in the form of ATP required for various cellular activities, hence known as the powerhouse of the cell.
2. Plastids: Chloroplasts trap solar energy for photosynthesis, while chromoplasts and leucoplasts provide color and store nutrients respectively.

Teacher's Note:
a) Energy released in mitochondria is stored as Adenosine Triphosphate (ATP).
b) Plastids are present exclusively in plant cells and Euglena.

71. Why is the cell known the 'fundamental and structural unit of life ' [2 Marks]

Answer:
1. A cell is the basic building block of all living organisms, providing structure and support to the body.
2. All vital life processes and metabolic reactions take place within a cell, making it the fundamental functional unit of life.

Teacher's Note:
a) Living organisms may be unicellular or multicellular.
b) The cell theory states that all living things are composed of cells.

72. What is a semi permeable membrane? what are the differences between semi permeable membrane and selectively permeable membrane? [3 Marks]

Answer:
1. A semi permeable membrane is a barrier that permits the passage of small solvent molecules like water while blocking larger solute molecules.
2. A semi permeable membrane allows passage based strictly on molecular size and pore dimensions.
3. A selectively permeable membrane actively selects which molecules or ions can pass through based on the cell's requirements, regardless of size.

Teacher's Note:
a) Cell membranes are selectively permeable, controlling the internal cellular environment.
b) Cellulose cell walls are fully permeable, allowing all substances to pass freely.
c) Understand the functional difference between passive pore size exclusion and active cellular regulation.

73. Which cell in the human body does not have the mitochondria? [1 Mark]

Answer:
1. Mature mammalian red blood cells (erythrocytes) do not have mitochondria.

Teacher's Note:
a) Absence of mitochondria in red blood cells ensures that the oxygen they carry is not consumed by themselves during transport.

74. What are plastids? Write their functions? [2 Marks]

Answer:
1. Plastids are double-membrane organelles found exclusively in plant cells and certain protists.
2. They perform functions such as photosynthesis (chloroplasts), imparting color to flowers and fruits (chromoplasts), and storing materials like starch, oils, and proteins (leucoplasts).

Teacher's Note:
a) Plastids contain their own DNA and ribosomes.
b) Chloroplasts contain the green pigment chlorophyll.

75. Which structure of animal cells forms the asters of spindle ? [1 Mark]

Answer:
1. Centrosome (or centrioles) forms the asters of spindle during cell division in animal cells.

Teacher's Note:
a) Centrosomes help in organizing microtubules during mitosis.

76. Name two semi- autonomous organelles? [1 Mark]

Answer:
1. Mitochondria and plastids are the two semi-autonomous organelles.

Teacher's Note:
a) They are called semi-autonomous because they possess their own circular DNA and ribosomes, enabling them to synthesize some of their own proteins.

77. Which cell organelle is rich in acid hydrolases? [1 Mark]

Answer:
1. Lysosomes are rich in acid hydrolase enzymes.

Teacher's Note:
a) Acid hydrolases function best in acidic environments maintained inside lysosomes.

78. Which cell organelles are called ribonucleoprotine particle? [1 Mark]

Answer:
1. Ribosomes are called ribonucleoprotein particles.

Teacher's Note:
a) Ribosomes are composed of ribosomal RNA (rRNA) and proteins.

79. Differentiate between SER and RER [3 Marks]

Answer:

Teacher's Note:
a) SER helps in detoxification of poisons and drugs in liver cells.
b) RER appears rough due to protein-making ribosomes studding its outer membrane.
c) Both are parts of the endomembrane system of the cell.

80. What is the difference between eukaryotes and prokaryotes? [3 Marks]

Answer:

Teacher's Note:
a) Bacteria and blue-green algae are examples of prokaryotes.
b) Plants, animals, fungi, and protists are eukaryotes.
c) Prokaryotic cells contain a single chromosome, whereas eukaryotes have multiple chromosomes.

81. What is the difference between osmosis and diffusion. [3 Marks]

Answer:

Teacher's Note:
a) Both are passive transport processes moving substances down their concentration gradient.
b) Osmosis is a special case of diffusion of water.
c) Mentioning the membrane requirement is essential for full marks.

82. Where are peroxisomes found ? [1 Mark]

Answer:
1. Peroxisomes are found in the cytoplasm of eukaryotic cells, particularly abundant in liver and kidney cells.

Teacher's Note:
a) They contain oxidative enzymes that break down toxic fatty acids and hydrogen peroxide.

83. What are the chemical reactions take place in cytoplasm, nucleoplasm, and in mitochondria? [3 Marks]

Answer:
1. Cytoplasm: Glycolysis and various metabolic reactions including protein synthesis and anaerobic pathways take place here.
2. Nucleoplasm: DNA replication, transcription, and synthesis of ribosomal RNA occur inside the nucleoplasm.
3. Mitochondria: Cellular respiration, the Krebs cycle, and oxidative phosphorylation take place to produce ATP.

Teacher's Note:
a) Each cellular compartment provides a specialized biochemical environment.
b) Compartmentalization prevents conflicting chemical reactions from interfering with each other.
c) Mitochondria are the primary sites of aerobic cellular respiration.

84. What is Diffusion? [2 Marks]

Answer:
1. Diffusion is the spontaneous movement of a substance from a region of higher concentration to a region of lower concentration.
2. It continues until the molecules are evenly distributed throughout the available space.

Teacher's Note:
a) It is an important passive transport mechanism for gases like carbon dioxide and oxygen across cell membranes.
b) No cellular energy (ATP) is consumed during diffusion.

85. What is dictyosomes ? [2 Marks]

Answer:
1. Dictyosomes are individual stack-like subunits that make up the Golgi apparatus in plant cells.
2. They are involved in modifying, sorting, and packaging proteins and synthesizing cell wall materials.

Teacher's Note:
a) In animal cells, the Golgi apparatus appears as a single interconnected complex.
b) In plant cells, multiple unfused units called dictyosomes are scattered throughout the cytoplasm.

86. What would happen if an animal cell is kept in distilled water for 24 hours. [2 Marks]

Answer:
1. Water will enter the animal cell continuously by endosmosis because distilled water is a hypotonic medium.
2. The cell will swell up and eventually burst due to the lack of a protective rigid cell wall.

Teacher's Note:
a) Plant cells do not burst in distilled water due to the rigid cell wall exerting turgor pressure.
b) This process in animal cells illustrates the importance of osmotic balance.

87. Give 5 examples of single celled organisms. [1 Mark]

Answer:
1. Amoeba, Paramecium, Euglena, Chlamydomonas, and Bacteria.

Teacher's Note:
a) Single-celled organisms are also known as unicellular organisms where a single cell performs all life functions.

88. What are multicellular organisms ? Give an example. [2 Marks]

Answer:
1. Organisms composed of many cells that work together, showing division of labor, are called multicellular organisms.
2. Example: Humans, dogs, mango trees, or birds.

Teacher's Note:
a) Cells in multicellular organisms differentiate to perform specialized functions.
b) Groups of cells form tissues, tissues form organs, and organs form organ systems.

89. Which cell organelle is commonly referred as the suicidal bags of the cell. [1 Mark]

Answer:
1. Lysosomes are commonly referred to as the suicidal bags of the cell.

Teacher's Note:
a) They rupture during cell damage to release digestive enzymes that destroy the cell itself.

90. Name the process through which an amoeba acquires its food from the external surroundings. [1 Mark]

Answer:
1. Endocytosis (specifically phagocytosis).

Teacher's Note:
a) Amoeba engulfs food particles using finger-like extensions of its cell membrane called pseudopodia.

91. State the functions of chromosome in a cell. [2 Marks]

Answer:
1. Chromosomes carry hereditary information in the form of genes from parents to offspring.
2. They control all cellular activities, protein synthesis, cell division, and cellular differentiation.

Teacher's Note:
a) Chromosomes are composed of DNA and proteins.
b) They become visible only during cell division.

92. What is Biogenisis? [2 Marks]

Answer:
1. Biogenesis is the principle that living organisms arise only from pre-existing living organisms.
2. It disproved the old theory of spontaneous generation.

Teacher's Note:
a) Louis Pasteur provided experimental proof for biogenesis.
b) Cell theory also supports biogenesis through the tenet that all cells arise from pre-existing cells.

93. Who discovered Golgi Apparatus? [1 Mark]

Answer:
1. Camillo Golgi discovered the Golgi apparatus.

Teacher's Note:
a) He first observed it in nerve cells of owls and cats using a staining technique called black reaction.

94. Name the cell organelle which is involved in the formation of lysosomes. [1 Mark]

Answer:
1. Golgi apparatus.

Teacher's Note:
a) Enzymes synthesized in the rough endoplasmic reticulum are packaged into vesicles by the Golgi apparatus to form lysosomes.

95. What is Endosmosis? [2 Marks]

Answer:
1. Endosmosis is the inward movement of water molecules into a cell through a semi permeable membrane when placed in a hypotonic solution.
2. This results in the swelling or turgidity of the cell.

Teacher's Note:
a) The reverse process, where water moves out of the cell, is called exosmosis.
b) Endosmosis occurs along the concentration gradient of water.