Cell: The Building Block of Life — Q&A
Think It Over · What If…? · Pause and Ponder · Threads of Curiosity · Ready to Go Beyond · Revise, Reflect, Refine · The Quest Continues
Explore detailed NCERT Class 9 Science “Cell: The Building Block of Life” Q&A covering Think It Over, Pause and Ponder, What If, and Revise, Reflect, Refine. Get clear answers on cell structure, organelles, osmosis, cell division, and cell theory with diagrams. Ideal for CBSE exam revision, homework help, and quick concept clarity. Includes solved questions on mitochondria, chloroplast, cell wall, plasma membrane, and more.
Think It Over
Q1. Where does a cell come from?
Answer:
The chapter discusses that life is believed to have originated in water, such as in oceans or small pools with changing environmental conditions. The first cells are thought to have originated from organic molecules that were protected by mineral deposits, eventually leading to the formation of the first protective membrane that defined a cell.
- Hot springs like Puga Valley, Ladakh, resemble early Earth conditions (~3.5 billion years ago) and contain thermophiles — unicellular, heat-loving bacteria.
- Scientists from the Birbal Sahni Institute of Palaeosciences, Lucknow, found calcium carbonate deposits that may have protected early organic molecules and helped form the first membrane-like barrier.
- A new cell comes from a pre-existing cell through cell division — cells do not form suddenly.
Q2. How have technological interventions facilitated the creation of new knowledge in understanding the world beyond the naked eye?
Answer:
Technological interventions like the invention of the light microscope and electron microscope have allowed scientists to see objects beyond the limit of resolution of the human eye (0.1 mm). These tools magnify cells and their organelles, enabling the study of their structure, function, and fine details at the nanometre scale, which has led to a deeper understanding of cell biology.
- Robert Hooke (1665): first observed cells in a thin slice of cork using a self‑designed microscope (200–300×).
- Electron microscope: uses a beam of electrons instead of light; reveals structures at the nanometre scale.
- Scientists have improved three main features: magnification, resolution (clarity), and contrast.
Q3. How is the cell structural and functional unit of life?
Answer:
All living organisms are made up of cells, which are the basic level at which life exists. Even in multicellular organisms, where cells are organized into tissues, organs, and organ systems, the cell remains the fundamental unit of structure and function. It performs all life processes and works together with other cells to maintain the organism's proper functioning.
- Structural unit: all living organisms are made of cells.
- Functional unit: all life activities — respiration, nutrition, growth, repair, reproduction — happen inside cells.
- Levels of organisation: Cells → Tissues → Organs → Organ Systems → Organism.
Q4. How does a cell multiply?
Answer:
Cells multiply through a process called cell division. This process allows new cells to be formed from pre-existing cells. There are two major types of cell division: mitosis, which is important for growth, repair, and maintenance, and meiosis, which is important for the production of gametes for sexual reproduction.
- Mitosis: one parent cell → two genetically identical daughter cells; chromosome number unchanged.
- Meiosis: one cell → four gametes, each with half the chromosome number.
- Importance: growth, repair of wounds, replacement of damaged cells, asexual reproduction (mitosis); genetic variation and sexual reproduction (meiosis).
What If…?
Q1. What if a cell is kept in salt or sugar solutions of different concentrations?
Answer:
When a cell is kept in solutions of different concentrations, the following occurs based on the tonicity of the solution relative to the cell:
| Solution Type | Comparison of Solute Concentration | Effect on Cell |
|---|---|---|
| Isotonic | Extracellular = Intracellular | No net movement of water; cell size remains the same. |
| Hypotonic | Extracellular < Intracellular | Water moves into the cell; cell swells. |
| Hypertonic | Extracellular > Intracellular | Water moves out of the cell; cell shrinks. |
Q2. What if mung bean seeds are kept in a concentrated solution after soaking in water for 12 hours? What will happen to them?
Answer:
When mung bean seeds are soaked in water for 12 hours, they absorb water and become swollen due to osmosis. If these swollen seeds are then placed in a concentrated salt or sugar solution:
- Water will move out of the seed cells into the concentrated solution through osmosis.
- The seeds will shrink and become wrinkled or shriveled.
Reason: The concentrated solution is hypertonic (has more solute) compared to the cell sap inside the seeds. Water moves from a region of higher water concentration (inside the seeds) to a region of lower water concentration (the concentrated solution) through the selectively permeable cell membrane. This causes the seeds to lose water and shrink.
Pause and Ponder
Q1. What argument would you give for the necessity of a cell wall in plants usually fixed in one place versus in animals usually moving from one place to the other?
Answer:
Plants are usually fixed in one place and need a rigid structure to withstand environmental stresses like wind and rain. The cell wall provides this rigidity, helping plants stay upright and maintaining their shape. In contrast, animals need to move, and a rigid cell wall would hinder this. The absence of a cell wall in animals allows for cellular flexibility, which is essential for movement and the functioning of animal tissues.
- Plant cell wall is mainly made of cellulose — a carbohydrate made of many glucose units.
- Cellulose in our diet acts as roughage, helping in digestion.
- Animal cells without a cell wall can change shape easily — helping in muscle contraction, white blood cells squeezing through capillaries, etc.
Q2. What consequences would you predict for a plant cell if its cell wall were to become as flexible as a cell membrane?
Answer:
If a plant cell's cell wall became as flexible as the cell membrane, it would lose its rigid structural support. The plant cell would not be able to maintain its shape, and the plant would likely wilt and be unable to stand upright against wind and rain. The cell would also not be able to withstand the osmotic pressure changes, as the rigid cell wall is crucial for preventing the cell from bursting in a hypotonic environment.
- Without a rigid wall, trees, grasses and crops would collapse.
- The wall also protects against mechanical injury and pathogen entry.
Q3. Why is it important to cut the two potato pieces in roughly equal size and measure their initial weight before placing them in different liquids?
Answer:
Cutting the two potato pieces in roughly equal size and measuring their initial weight is important to ensure that the experiment is a fair test. This minimizes variables other than the liquid they are placed in. By having two pieces as similar as possible initially, any observed differences in their final weight or texture can be attributed to the effect of the different liquids (plain water vs. salt/sugar solution) and the process of osmosis.
- Fair test: only the surrounding solution should differ between the two set-ups.
- Control of variables: size, surface area and starting mass must be the same.
- Measurable change: comparing initial and final weights gives quantitative evidence of water movement.
Q4. Do white flowers contain any pigment? Give reasons.
Answer:
White flowers do not contain any pigments. The plastids in their petal cells are typically leucoplasts, which are colorless plastids. The white color is due to the reflection of all wavelengths of light, rather than the presence of specific pigments like anthocyanins (which produce red, purple, or blue colors) or carotenoids (which produce yellow, orange, or red colors).
- Colour in flowers comes from pigments such as chlorophyll (green), carotenoids (yellow/orange/red) and anthocyanins (red/blue/purple).
- White petals lack these pigments; the air spaces between cells scatter light, making the petal look white.
Q5. Draw a well-labelled schematic diagram of a plant or an animal cell using these clues: (You may refer to Fig. 2.10.)
1. Nucleus appears as a dark and round body inside the cell.
2. ER spreads like a network of extended nuclear envelopes.
3. Mitochondria and chloroplasts are rod-shaped.
Answer:
a) A typical Plant cell and b) a typical animal cell
- Plant cell: Cell wall, cell membrane, vacuole (large central), chloroplast (rod-shaped), nucleus (dark, round), nucleolus, endoplasmic reticulum (network), mitochondria (rod-shaped), cytoplasm, Golgi body, ribosome.
- Animal cell: Cell membrane, vacuole (small), lysosome, nucleus (dark, round), nucleolus, endoplasmic reticulum, mitochondria (rod-shaped), cytoplasm, Golgi body, ribosome.
Q6. Instead of many small ones, why does a cell not have a single giant mitochondrion? How does this relate to the concept of surface area?
Answer:
A cell does not have a single giant mitochondrion but many small ones because a large number of smaller mitochondria provides a much greater total surface area for energy-producing chemical reactions. The inner membrane of mitochondria is folded into cristae to increase surface area. Having many mitochondria maximizes this surface area, which allows for a higher rate of ATP production. If there were a single giant mitochondrion, its surface area-to-volume ratio would be much lower, limiting its efficiency in energy production.
- Many small mitochondria together provide a much larger total membrane surface area than one large sphere of the same volume.
- More surface area = more space for enzymes and reactions = more ATP produced per unit time.
- Small mitochondria can also be moved to different parts of the cell where energy is needed most.
Q7. If the skin cells start dividing by meiosis instead of mitosis, what do you think will happen to a cut on the skin?
Answer:
If skin cells started dividing by meiosis, a cut on the skin would not heal effectively. Meiosis produces four genetically different daughter cells with half the number of chromosomes, which are gametes. It is not a process for growth or repair. Mitosis is the type of cell division responsible for producing identical daughter cells for growth and repair. Therefore, without mitosis, the wound would not be repaired, and the normal function and integrity of the skin would be compromised.
- Mitosis produces two identical diploid cells — perfect for growth and repair.
- Meiosis produces four genetically different haploid cells — meant only for reproduction.
- Using meiosis for repair would also create genetic variation in body cells, which could lead to abnormal tissue growth.
Threads of Curiosity
Q1. Mature Red Blood Cells (RBCs) in humans do not have a nucleus (enucleate). Do you know any other cells without nucleus?
Answer:
Yes, besides mature Red Blood Cells (RBCs), other examples of cells without a nucleus include:
- Platelets (Thrombocytes): These are small cell fragments involved in blood clotting and do not contain a nucleus.
- Sieve tube elements: These are specialized cells in the phloem of plants that transport sugars. They lose their nucleus and most other organelles at maturity to allow for efficient transport.
- Prokaryotic cells: They do not have a well-defined nucleus. Their genetic material is present in a region called the nucleoid, which is not enclosed by a nuclear membrane.
Ready to Go Beyond
Q1. Explore different ways by which cells maintain themselves.
Answer:
Cells maintain themselves through several processes:
- Programmed Cell Death (PCD): A genetically regulated process of selective cell destruction, essential for development and removing damaged cells.
- Lysosomes: They act as the cell's clean-up system, breaking down waste materials and damaged organelles.
- Contact Inhibition: Normal cells stop dividing when they come in contact with neighboring cells, preventing overcrowding and maintaining tissue structure.
- Cell Cycle Control: The process of cell division (mitosis and meiosis) is highly regulated to ensure it occurs in a controlled and orderly manner.
- DNA Repair Mechanisms: Cells have systems to identify and repair errors in their DNA to maintain genetic integrity.
These mechanisms help cells function, grow, and divide correctly, contributing to the health and proper functioning of the entire organism.
Revise, Reflect, Refine
Q1. Differentiate between the following pairs of terms based on the clues given in parentheses:
1. Cell membrane and cell wall (permeability)
2. RER and SER (structure)
3. Chloroplasts and chromoplasts (pigments)
Answer:
(i) Cell membrane and cell wall (permeability):
| Feature | Cell Membrane | Cell Wall |
|---|---|---|
| Permeability | Selectively permeable (allows some substances to pass while blocking others) | Permeable (water and some dissolved minerals can pass through it) |
(ii) RER and SER (structure):
| Feature | Rough Endoplasmic Reticulum (RER) | Smooth Endoplasmic Reticulum (SER) |
|---|---|---|
| Structure | Has ribosomes attached to its surface, giving it a rough appearance. | Does not have ribosomes on its surface, hence it looks smooth. |
(iii) Chloroplasts and chromoplasts (pigments):
| Feature | Chloroplasts | Chromoplasts |
|---|---|---|
| Pigments | Contain chlorophyll (green pigment) for photosynthesis. | Contain pigments other than chlorophyll, such as yellow, orange, or red pigments. |
Q2. Two similar animal cells are placed in two different solutions: Cells are observed after some time. Cell X swells, and Cell Y shrinks. Which statement provides the correct explanation for the above observations?
Cell X is placed in pure water.
Cell Y is placed in a concentrated salt solution.
1. Salt molecules moved into Cell Y, causing it to shrink.
2. Water moved into Cell X and more water moved out of Cell Y than the salt solution entered in it.
3. Water moved into Cell X and moved out of Cell Y through the cell membrane.
4. Solute movement caused osmosis in both cells.
Answer:
The correct statement is (iii) Water moved into Cell X and moved out of Cell Y through the cell membrane.
Explanation: This observation is due to osmosis. Pure water is a hypotonic solution compared to the cell's interior, so water moves into Cell X, causing it to swell. The concentrated salt solution is hypertonic, so water moves out of Cell Y, causing it to shrink. The cell membrane is selectively permeable, allowing water to pass through but not the solute molecules.
Q3. Look at the diagram of a cell in Fig. 2.20. Identify the parts labelled from (a) to (g) and correctly match them with their functions given below:
1. Controlling all the activities of a cell.
2. Site of cellular respiration.
3. Storage organelle that also provides rigidity to the cell.
4. Separates the cell contents from surroundings.
5. Provides structural rigidity to the cell.
6. Packs and stores materials received from ER.
Answer:
Correct Matching:
| Label | Part of Cell | Function (Matching Number) |
|---|---|---|
| (a) | Mitochondria | (ii) Site of cellular respiration. |
| (b) | Nucleus | (i) Controlling all the activities of a cell. |
| (c) | Golgi Apparatus | (vi) Packs and stores materials received from ER. |
| (d) | Chloroplast | (vii) Helps in manufacturing food. |
| (e) | Cell Membrane | (iv) Separates the cell contents from surroundings. |
| (f) | Cell wall | (v) Provides structural rigidity to the cell. |
| (g) | Vacuole | (iii) Storage organelle that also provides rigidity to the cell. |
Q4. Which of the following option(s) of the pairs of cell organelles are correctly placed under the given categories?
| Option | Present in the plant cells | Absent in the animal cells |
|---|---|---|
| (i) | Leucoplast | Cell wall |
| (ii) | Mitochondria | Ribosome |
| (iii) | Cell wall | Golgi apparatus |
| (iv) | Lysosome | Endoplasmic reticulum |
Answer:
The correct option is (i) Leucoplasts are present in plant cells, and cell walls are absent in animal cells.
Explanation:
- Leucoplast: These are plastids found in plant cells (e.g., for starch storage). They are absent in animal cells.
- Cell wall: This is a rigid outer covering found in plant cells, which is absent in animal cells.
The other options are incorrect for the following reasons:
- Mitochondria and ribosomes are present in both plant and animal cells.
- Golgi apparatus is present in both plant and animal cells.
- Lysosomes are primarily found in animal cells and are rare in plant cells, while the endoplasmic reticulum is present in both.
Q5. Two students, Renu and Rohit, were having a discussion on the plastids. Renu emphasised that all parts of the plants, even roots, contain plastids. However, Rohit did not agree with the statement and told her that plastids are absent in plant roots since the roots are underground and do not need to perform photosynthesis. Who is correct? Justify your answer.
Answer:
Renu is correct. Plastids are present in all parts of plants, including roots.
While it is true that roots are underground and do not perform photosynthesis, they contain other types of plastids, such as leucoplasts. Leucoplasts are colorless plastids that store food materials like starch, oils, or proteins. This is essential for the root cells to store nutrients. Chloroplasts, which contain chlorophyll for photosynthesis, are mostly found in the green parts of the plant, but other plastids like leucoplasts are found throughout the plant, including in roots.
Q6. Mitochondria and chloroplasts are two important organelles in a plant cell. Discuss how these two organelles are structurally and functionally similar to each other, and different from each other.
Answer:
Similarities between Mitochondria and Chloroplasts:
- Double Membrane: Both are surrounded by two membranes (outer and inner).
- DNA and Ribosomes: Both contain their own DNA and ribosomes, allowing them to make some of their own proteins, which suggests a shared evolutionary history with bacteria.
- Energy-Related Functions: Both are involved in energy conversion processes. Mitochondria are involved in cellular respiration to release energy, and chloroplasts are involved in photosynthesis to capture and store energy.
Differences between Mitochondria and Chloroplasts:
| Feature | Mitochondria | Chloroplasts |
|---|---|---|
| Function | Site of cellular respiration (breakdown of glucose to release energy as ATP). | Site of photosynthesis (synthesize food using sunlight, water, and carbon dioxide). |
| Pigments | Do not contain pigments. | Contain chlorophyll (green pigment) and other pigments. |
| Structure of Inner Membrane | Inner membrane is folded into finger-like projections called cristae. | Inner membrane forms disc-shaped structures called thylakoids, stacked into grana. |
| Presence | Found in both plant and animal cells. | Found only in plant cells and some algae. |
Q7. Which of the following pairs of cell organelles contains DNA?
1. Chloroplasts, Ribosomes
2. Mitochondria, Nucleus
3. Golgi bodies, Ribosomes
4. Nucleus, Lysosomes
Answer:
The correct pair is (ii) Mitochondria, Nucleus.
Explanation:
- The nucleus contains the cell's main DNA, which is organized into chromosomes.
- Mitochondria also contain their own DNA.
- Chloroplasts also contain DNA, but they are not paired with another DNA-containing organelle in the options except in option (iv), which lists lysosomes, but lysosomes do not contain DNA.
- Ribosomes, Golgi bodies, and lysosomes do not contain DNA.
Q8. A researcher carried out an experiment in which she took two carrots of similar size. She placed one carrot in plain water and the other carrot in concentrated salt solution (Fig. 2.21). After 24 hours she recorded her observations.
1. What hypothesis does she want to test through this experiment?
2. What would you suggest for the improvement of this experiment?
3. Why does the carrot in plain water stay stiff and crunchy, but the carrot in concentrated salt solution become rubbery and limp?
Answer:
(i) Hypothesis: The researcher likely wants to test the hypothesis that the movement of water into or out of the carrot cells, through osmosis, will cause a change in the carrot's texture and firmness depending on the concentration of the external solution.
(ii) Improvement: For a more controlled and quantitative experiment, she could:
- Record the initial and final weight and volume of the carrots.
- Use a larger sample size (multiple carrots per condition) to ensure reliability.
- Ensure the temperature is kept constant for both setups.
- Measure the solute concentration of the solutions used.
(iii) Explanation:
In plain water, which is a hypotonic solution, water moves into the carrot cells by osmosis. The cells become turgid (swollen with water), making the carrot stiff and crunchy. In the concentrated salt solution, which is a hypertonic solution, water moves out of the carrot cells by osmosis. This causes the cells to lose water and become flaccid, leading to the carrot becoming rubbery and limp.
Q9. Indicate the presence or absence of the following structures in bacterial and animal cells:
| Structures in a cell | Bacterial cell | Animal cell |
|---|---|---|
| Chromosome | Present (in nucleoid region) | Present (in nucleus) |
| Nucleus | Absent | Present |
| Mitochondria | Absent | Present |
| Golgi complex | Absent | Present |
| Chromoplasts | Absent | Absent |
Q10. Carry out the following 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. Place each of the potato cups in a beaker containing water (Fig. 2.22). Now, set up the experiment as follows: Observe the four potato cups at least two hours and answer the following questions:
1. Keep Cup A empty.
2. Add one teaspoon sugar in Cup B.
3. Add one teaspoon salt in Cup C.
4. Add one teaspoon sugar in the boiled potato in Cup D.
1. Explain why water gathers in the hollowed portion of Cup B and Cup C.
2. Why is Cup A necessary for this experiment?
3. Explain why water does not gather in the hollowed portions of Cups A and D.
Answer:
(i) Why water gathers in the hollowed portion of Cup B and Cup C:
Water gathers in the hollowed portions of Cup B (sugar) and Cup C (salt) due to osmosis. The potato cells have a selectively permeable membrane. The sugar or salt solution inside the cup creates a hypertonic solution compared to the water outside. Water from the beaker moves through the potato cells into the cup, where the solute concentration is higher. This movement of water (osmosis) causes water to accumulate in the hollowed portion of the cup.
(ii) Why Cup A is necessary for this experiment:
Cup A, which is empty, acts as a control. It shows that water does not gather in the cup without a solute. This confirms that the water accumulation in Cups B and C is due to the presence of sugar or salt, not any other factor.
(iii) Why water does not gather in the hollowed portions of Cups A and D:
- Cup A: No solute is present, so there is no concentration gradient to drive the movement of water into the cup. The conditions are isotonic, so there is no net movement of water.
- Cup D: The potato is boiled. Boiling destroys the cell membrane, making it non-selective and effectively killing the cells. Therefore, it can no longer act as a selectively permeable membrane, and osmosis cannot occur. Without a functional membrane, water does not accumulate in the cup.
Q11. Identify the pair that incorrectly matches the cell organelle with its function.
1. Ribosome — Protein synthesis
2. SER — Lipid and cellulose synthesis
3. Lysosome — Digestion of foreign agents
Answer:
The incorrect match is (ii) SER — Lipid and cellulose synthesis.
Explanation: Smooth Endoplasmic Reticulum (SER) is involved in the synthesis and storage of fats (lipids) and hormones. It is not involved in cellulose synthesis. Cellulose is a structural component of plant cell walls and is synthesized at the cell membrane by enzyme complexes.
Q12. What outcome do you expect, if all the mitochondria are removed from a eukaryotic cell?
Answer:
If all mitochondria are removed from a eukaryotic cell, the cell would be unable to produce ATP (energy) through aerobic cellular respiration. This would lead to a severe energy deficiency, as mitochondria are the 'powerhouses' of the cell. Most cellular activities requiring energy would cease, and the cell would likely die. Some cells might survive for a short time using anaerobic pathways, but they would not be able to function normally or perform complex tasks.
Q13. Which phenomenon inhibits the formation of tumors in the human body? Can plants also develop tumors? Explain.
Answer:
The phenomenon that inhibits the formation of tumors in the human body is contact inhibition. In many animal cells, cell division usually stops when cells come in contact with neighboring cells. Cancer cells lose this control and keep dividing uncontrollably, leading to the formation of tumors.
Yes, plants can also develop tumors. These are often called galls. However, plant cells do not show contact inhibition. Plant tumors are typically caused by infections from bacteria (like Agrobacterium tumefaciens), fungi, or insects. They follow a different pattern of growth compared to animal tumors.
Q14. The cell membrane of a cell is made up of proteins and lipids. Which cell organelles help in the synthesis of cell membrane? Write the path of these compounds from their site of synthesis to the cell membrane and show this through a labelled diagram.
Answer:
The cell organelles that help in the synthesis of the cell membrane are:
- Rough Endoplasmic Reticulum (RER): Responsible for synthesizing proteins.
- Smooth Endoplasmic Reticulum (SER): Responsible for synthesizing lipids.
Pathway from Synthesis to Cell Membrane:
- Synthesis: Proteins are synthesized on ribosomes attached to the RER, and lipids are synthesized on the SER.
- Transport to Golgi Apparatus: Proteins and lipids are packaged into vesicles that bud off from the ER and travel to the Golgi apparatus.
- Modification and Packaging: The Golgi apparatus modifies, sorts, and packages these proteins and lipids into new vesicles.
- Transport to Cell Membrane: These vesicles then travel to and fuse with the cell membrane, delivering the proteins and lipids to the membrane.
Q15. What would happen if gametes are formed by mitotic divisions?
Answer:
If gametes were formed by mitotic divisions, the chromosome number would not be halved. Mitosis produces two genetically identical daughter cells with the same number of chromosomes as the parent cell. Therefore, gametes would be diploid (2n) instead of haploid (n). During fertilization, the fusion of two diploid gametes would result in a zygote with double (4n) the normal number of chromosomes. This would lead to a doubling of the chromosome number in each generation, causing genetic imbalances and likely resulting in the offspring's death or severe developmental problems.
Q16. A farmer, Deepa, was very happy with the harvest of amla (Indian Gooseberry) and lemons on her farm. However, she could sell only one-fourth of the produce in the local market. Recognising that a significant amount of produce may be lost post-harvest, she employed a traditional yet scientifically sound method to extend the shelf life of amla and lemons. She turned perishable produce into profitable products, such as pickles and sharbat. She used the excess produce to prepare pickles, murabbas, and sharbat by adding appropriate amounts of salt, sugar, or jaggery to small pieces of fruit and their juices. These were then stored in small glass bottles for sale, helping her prevent the wastage of post-harvest produce. This shift from farming to agro-processing would strengthen food security and boost the local economy, creating a sustainable model that cuts waste while increasing her income. Based on the above passage answer the following questions:
1. Which scientific concept has the farmer applied in the preservation of the farm produce?
2. How does the addition of high concentrations of salt and sugar create an environment that prevents the growth of spoilage-causing bacteria and fungi?
3. Suggest a healthy recipe of this kind for food preservation.
4. What are the scientific values addressed in this case?
Answer:
(i) Scientific Concept: The farmer, Deepa has applied the concept of osmosis for food preservation. Adding high concentrations of salt or sugar creates a hypertonic environment.
(ii) How it Prevents Growth: The high concentration of salt or sugar outside the microbial cells causes water to move out of the bacteria or fungi cells through osmosis. This leads to dehydration (plasmolysis) of the microbes, inhibiting their growth and reproduction, thus preventing spoilage.
(iii) Healthy Recipe for Food Preservation: A simple and healthy recipe is making lemon pickle. Cut lemons into small pieces and remove the seeds, mix with a high amount of salt and a little turmeric powder, and store in a clean, dry glass jar. The high salt concentration preserves the lemons, and the lemon's natural acidity further helps in preservation. It can be kept for months without refrigeration.
(iv) Scientific Values Addressed:
- Application of Science: Using the scientific principle of osmosis in a traditional practice.
- Problem-Solving: Addressing the practical problem of post-harvest loss.
- Sustainability: Reducing waste by using the entire produce.
- Economic Empowerment: Increasing farmer's income and boosting the local economy through agro-processing.
- Food Security: Ensuring the availability of food for a longer period.
The Quest Continues
Q1. What is the future of the development of synthetic cells using non-living chemicals? If a synthetic cell is developed, what may be the related ethical issues?
Answer:
Future of Synthetic Cells: The future of synthetic cell development could lead to the creation of cells with novel functions, such as producing medicines, breaking down pollutants, or even creating biofuels more efficiently. It could revolutionize biotechnology and medicine.
Ethical Issues: If a synthetic cell is developed, several ethical issues may arise, including:
- Playing God: Concerns about humans creating life from non-living chemicals.
- Biosafety: The potential for synthetic cells to escape the lab and cause unforeseen ecological damage or compete with natural organisms.
- Biosecurity: The potential misuse of the technology to create harmful biological weapons.
- Patenting Life: Legal and moral questions about whether synthetic cells can be patented and owned.
- Equity and Access: Who would have access to this technology and its benefits, and who would be left out.
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