1. The cell was discovered by __________ in the year __________.
2. The term "cell" comes from the Latin word __________ meaning small room.
3. __________ was the first scientist to observe living cells in pond water.
4. The nucleus in plant cells was discovered by __________.
5. According to cell theory, all cells arise from __________.
6. The three postulates of cell theory were proposed by __________, __________, and __________.
7. Organisms that lack a well-defined nucleus are called __________.
8. __________ and __________ are examples of prokaryotic organisms.
9. The genetic material in prokaryotic cells is present in a region called the __________.
10. Eukaryotic cells have a well-defined nucleus surrounded by a __________.
11. The plasma membrane is also called the __________ membrane.
12. The plasma membrane is __________ permeable, allowing only certain substances to pass through.
13. The cell membrane is primarily composed of __________ and __________.
14. The fluid mosaic model of the cell membrane was proposed by __________ and __________.
15. Plant cell walls are mainly made of __________, while fungal cell walls contain __________.
16. The movement of water molecules through a selectively permeable membrane is called __________.
17. When a cell is placed in a hypertonic solution, water moves __________ the cell.
18. The shrinkage of plant cell cytoplasm away from the cell wall is called __________.
19. __________ is the movement of molecules from high concentration to low concentration.
20. The powerhouse of the cell is __________.
21. Mitochondria produce energy in the form of __________.
22. ATP stands for __________.
23. The sites of protein synthesis in a cell are __________.
24. Ribosomes are composed of RNA and __________.
25. The endoplasmic reticulum with ribosomes is called __________ ER.
26. The ER without ribosomes is called __________ ER and is involved in __________ synthesis.
27. The packaging and dispatching center of the cell is the __________.
28. Lysosomes are also known as __________ bags because they contain digestive enzymes.
29. Lysosomes are formed from the __________.
30. __________ are found only in plant cells and perform photosynthesis.
31. The green pigment in chloroplasts is called __________.
32. Chromoplasts provide __________ color to flowers and fruits.
33. __________ are colorless plastids that store food materials.
34. The membrane surrounding a vacuole is called the __________.
35. Plant cells have __________ vacuoles compared to animal cells.
36. The control center of the cell is the __________.
37. Chromosomes are made up of __________ and proteins.
38. __________ is the type of cell division that produces two identical daughter cells.
39. __________ is the type of cell division that produces four haploid gametes.
40. The four stages of mitosis in order are __________, __________, __________, and __________.

1. Robert Hooke observed living cells in cork.
2. All cells arise from pre-existing cells.
3. Viruses are exceptions to cell theory.
4. Prokaryotic cells have a well-defined nucleus.
5. Blue-green algae are prokaryotic organisms.
6. Eukaryotic cells are generally larger than prokaryotic cells.
7. Animal cells have a cell wall.
8. The cell wall in plants is made of chitin.
9. The plasma membrane is completely permeable to all substances.
10. Osmosis is the movement of any molecule through a membrane.
11. When a cell is placed in a hypotonic solution, it swells.
12. Plasmolysis occurs when a plant cell is placed in distilled water.
13. Animal cells burst in hypotonic solutions due to lack of a cell wall.
14. Diffusion requires energy in the form of ATP.
15. Mitochondria have their own DNA and ribosomes.
16. Chloroplasts are found in both plant and animal cells.
17. Ribosomes are membrane-bound organelles.
18. Rough ER has ribosomes attached to its surface.
19. Smooth ER is involved in protein synthesis.
20. The Golgi apparatus modifies and packages proteins.
21. Lysosomes contain digestive enzymes.
22. Lysosomes are called the powerhouse of the cell.
23. Vacuoles in plant cells store water and maintain turgor pressure.
24. Animal cells have larger vacuoles than plant cells.
25. The nucleus contains chromosomes made of DNA and proteins.
26. The nucleus is surrounded by a single membrane.
27. Chromoplasts perform photosynthesis.
28. Leucoplasts are involved in storage of food materials.
29. Amyloplasts store proteins.
30. Mitochondria are called the suicide bags of the cell.
31. Mitosis maintains the chromosome number in daughter cells.
32. Meiosis produces four diploid daughter cells.
33. Mitosis occurs in reproductive cells to form gametes.
34. Meiosis introduces genetic variation through crossing over.
35. During metaphase, chromosomes align at the cell's equator.
36. Cytokinesis is the division of the cytoplasm.
37. Plant cells divide by mitosis in meristematic regions.
38. Cancer is caused by controlled cell division.
39. The endosymbiotic theory explains the origin of mitochondria and chloroplasts.
40. Red blood cells in humans contain a nucleus.

Set 1: Scientists and Discoveries

Set 2: Cell Organelles and Functions

Set 3: Terms and Definitions

Set 4: Cell Structures and Composition

Set 5: Cell Division Stages

Set 6: Cell Types and Examples

Set 1: Organelle Characteristics

Set 2: Transport Processes

Set 3: Cell Division Types

Set 4: Plastid Types and Functions

Diagram 1: Plant Cell

Source: Standard NCERT Class 9 Biology textbook, Figure 5.3 (Plant Cell Structure)

Parts to label:

1. Cell wall
2. Cell membrane (plasma membrane)
3. Nucleus
4. Nuclear membrane
5. Nucleolus
6. Cytoplasm
7. Chloroplast
8. Vacuole
9. Mitochondria
10. Endoplasmic reticulum
11. Golgi apparatus
12. Ribosomes

Refer to: Activity 2.3 and Cell Organelles page

Diagram 2: Animal Cell

Source: Standard NCERT Class 9 Biology textbook, Figure 5.4 (Animal Cell Structure)

Parts to label:

1. Cell membrane
2. Nucleus
3. Nuclear membrane
4. Nucleolus
5. Cytoplasm
6. Mitochondria
7. Endoplasmic reticulum (Rough and Smooth)
8. Golgi apparatus
9. Ribosomes
10. Lysosomes
11. Centrosome with centrioles
12. Vacuoles (small)

Compare with plant cell in Activity 2.3

Diagram 3: Structure of Mitochondrion

Source: NCERT Class 9 Biology, Figure showing mitochondria structure (cross-section)

Parts to label:

1. Outer membrane
2. Inner membrane
3. Cristae (folds of inner membrane)
4. Matrix
5. Ribosome (mitochondrial)
6. DNA (mitochondrial)

Learn more: Cell Organelles

Diagram 4: Prokaryotic Cell (Bacterial Cell)

Source: NCERT Class 9 Biology, Figure showing prokaryotic cell structure

Parts to label:

1. Cell wall
2. Cell membrane
3. Cytoplasm
4. Nucleoid (genetic material/DNA)
5. Ribosomes (70S type)
6. Plasmid
7. Flagellum
8. Pili

Compare with eukaryotic cells: Prokaryotic vs Eukaryotic

Diagram 5: Stages of Mitosis

Source: NCERT Class 9 Biology, showing four stages of mitosis in sequential order

Draw four stages and label:

Stage 1 - Prophase:

• Condensed chromosomes
• Spindle fibers forming
• Nuclear membrane breaking down
• Centrioles at poles

Stage 2 - Metaphase:

• Chromosomes at equatorial plate
• Spindle fibers attached to centromeres

Stage 3 - Anaphase:

• Sister chromatids separating
• Chromatids moving to opposite poles

Stage 4 - Telophase:

• Chromosomes at poles
• Nuclear membrane reforming
• Cytokinesis beginning

See stages in: Mitosis and Activity 2.5

Codes:
(a) Both A and R are true, and R is the correct explanation of A
(b) Both A and R are true, but R is NOT the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true
(e) Both A and R are false

1. Assertion (A): Plant cells do not burst when placed in distilled water.
   Reason (R): Plant cells have a rigid cell wall that prevents bursting.
2. Assertion (A): Mitochondria are called the powerhouse of the cell.
   Reason (R): Mitochondria synthesize proteins for the cell.
3. Assertion (A): Prokaryotic cells are simpler than eukaryotic cells.
   Reason (R): Prokaryotic cells lack a well-defined nucleus and membrane-bound organelles.
4. Assertion (A): Lysosomes are known as suicide bags.
   Reason (R): Lysosomes contain digestive enzymes that can break down cellular components.
5. Assertion (A): Osmosis is a passive process.
   Reason (R): Osmosis does not require ATP energy for water movement.
6. Assertion (A): Meiosis is essential for sexual reproduction.
   Reason (R): Meiosis maintains the chromosome number in gametes.
7. Assertion (A): Chloroplasts are found only in plant cells.
   Reason (R): Only plant cells perform photosynthesis.
8. Assertion (A): The cell membrane is selectively permeable.
   Reason (R): It allows all substances to pass through freely.
9. Assertion (A): Mitosis maintains the chromosome number in daughter cells.
   Reason (R): Each daughter cell receives the same number of chromosomes as the parent cell.
10. Assertion (A): Ribosomes are not membrane-bound organelles.
    Reason (R): Ribosomes are made of RNA and proteins.
11. Assertion (A): Plasmolysis occurs when a cell is placed in a hypertonic solution.
    Reason (R): Water moves out of the cell, causing the cytoplasm to shrink.
12. Assertion (A): Cell wall provides structural support to plant cells.
    Reason (R): Cell wall is made of chitin in plants.
13. Assertion (A): Mitochondria and chloroplasts have their own DNA.
    Reason (R): They originated from free-living bacteria according to endosymbiotic theory.
14. Assertion (A): Cancer is caused by uncontrolled cell division.
    Reason (R): Cell division checkpoints fail in cancer cells.
15. Assertion (A): Smooth ER is involved in lipid synthesis.
    Reason (R): Smooth ER has ribosomes attached to its surface.

1. Why do vegetables release water and become soft when salt is sprinkled on them? Explain the process involved and predict what would happen if these vegetables are then placed in plain water.
2. A student observes two types of cells under a microscope - one from onion peel and one from human cheek. What differences would the student observe? Explain the reason for each difference.
3. If the plasma membrane of a cell ruptures, what would be the immediate consequences for the cell? Will the cell survive? Justify your answer.
4. Root hair cells have very large surface areas. How does this structural feature help them perform their function more efficiently? Relate this to the process of osmosis.
5. Muscle cells contain a large number of mitochondria. Nerve cells also contain many mitochondria. Why do these cells need more mitochondria compared to other cells?
6. A person with a mitochondrial disease experiences severe muscle fatigue. Explain why muscles are particularly affected in mitochondrial disorders.
7. Why do cells not continue to grow larger indefinitely? What limits the size of cells? Explain using the concept of surface area to volume ratio.
8. If you place a drop of blood in distilled water, the red blood cells will burst. But if you place the same drop in a salt solution, they shrink. Explain both observations.
9. Why is cell division necessary for growth in multicellular organisms? Why can't organisms simply grow by increasing the size of their cells?
10. A scientist discovers a new organism that appears to be made of cells but these cells lack mitochondria. How might this organism produce energy? What type of respiration would it likely use?
11. Explain why chemotherapy (cancer treatment) causes hair loss and digestive problems as side effects, even though it is meant to kill cancer cells.
12. If you examine a cell that has many Golgi apparatus and rough ER, what can you infer about the function of this cell? Give an example of such a cell in the human body.

Question 1: Osmosis Experiment with Potato Cups

Carry out the following osmosis experiment:

Take four peeled potato halves and scoop each one out to make potato cups. One of these potato cups should be made from a boiled potato. Put each potato cup in a trough containing water. Now,

1. Keep cup A empty
2. Put one teaspoon sugar in cup B
3. Put one teaspoon salt in cup C
4. Put one teaspoon sugar in the boiled potato cup D

Keep these for two hours. Then observe the four potato cups and answer the following:

1. Explain why water gathers in the hollowed portion of B and C.
2. Why is potato A necessary for this experiment?
3. Explain why water does not gather in the hollowed out portions of A and D.

Question 2: Identify the Tissue

Identify the tissue in the following locations:

1. Lining of small intestine
2. Which connects muscle to bone
3. Iris of eye
4. Base of leaves
5. Leaf stalk below epidermis
6. Vascular bundles

Cell Biology Crossword

ACROSS:

3. _____ stands for DeoxyriboNucleic Acid (3 letters)
4. These are important for photosynthesis in plants (11 letters)

DOWN:

1. They are the powerhouses of the cell (12 letters)
2. Paramecium is a ____________ organism (11 letters)
3. It is a kind of waste disposal system of the cell (9 letters)
4. One of the biologists who presented the cell theory (9 letters)

💡 Hint: Review cell organelles and cell theory before attempting this puzzle!