Cell Organelles – Long Answer Questions
Medium Level (Application & Explanation)
Q1. Differentiate between RER and SER. Explain how both together help in building the cell and its functions.
Answer:
- The Rough ER (RER) has ribosomes on its surface. It makes proteins.
- The Smooth ER (SER) has no ribosomes. It makes lipids (fats).
- Proteins from RER and lipids from SER move to the Golgi apparatus for processing.
- Together, they help make and repair cell membranes using proteins and lipids.
- They also help in transport of materials inside the cell.
- This teamwork keeps the cell organized and its activities separated.
- Thus, ER acts as a framework and highway for cell materials.
Q2. The Golgi apparatus is called the “post office” of the cell. Explain this with the journey of a protein from ER to outside the cell.
Answer:
- The RER makes a protein and packs it into a small vesicle.
- This vesicle travels to the Golgi apparatus (stack of cisterns).
- The Golgi modifies the protein. It may add sugars to make a complex product.
- The Golgi then stores and packages it into a new vesicle.
- The vesicle moves to the cell membrane and may be secreted outside.
- During this process, the Golgi also helps form lysosomes.
- So, Golgi acts like a sorting, labeling, and delivery center.
Q3. Describe the structure of mitochondria and explain how it helps in making energy for the cell.
Answer:
- Mitochondria have two membranes.
- The outer membrane is porous, so materials can pass easily.
- The inner membrane is folded. This gives a large surface area for reactions.
- These reactions help make ATP, the energy currency of the cell.
- Mitochondria also have their own DNA. They can make some proteins.
- This makes mitochondria fast and efficient at energy production.
- So, they are rightly called the powerhouses of the cell.
Q4. What are lysosomes? Explain their structure and role in protection and cleaning of the cell.
Answer:
- Lysosomes are membrane-bound sacs.
- They contain digestive enzymes made by the RER.
- They digest foreign materials like bacteria entering the cell.
- They also break down old or worn-out organelles.
- In severe cell damage, they can burst and digest the cell. These are called “suicide bags.”
- Thus, lysosomes act as the cell’s waste disposal and defense units.
- They keep the cell clean and safe.
Q5. Explain the role of vacuoles in plant cells. Why are they larger in plants than in animals?
Answer:
- Vacuoles are storage sacs for water, sugars, and amino acids.
- In plant cells, vacuoles are large and can occupy 50–90% of the cell.
- They help maintain turgidity and rigidity in plant cells.
- This keeps leaves and stems upright.
- In single-celled organisms, vacuoles also help expel extra water and waste.
- Animal cells have smaller vacuoles because they do not need such high turgor pressure.
- So, vacuoles support storage and structure in plants.
High Complexity (Analysis & Scenario-Based)
Q6. A cell’s Golgi apparatus stops working due to a toxin. Predict what will happen to protein secretion, lysosome formation, and overall cell health.
Answer:
- Proteins from the ER will not be properly modified or packaged.
- Vesicles for secretion will not form correctly. Secreted products will decline.
- Lysosome formation will be reduced, since Golgi helps form them.
- Undigested wastes and worn-out organelles will accumulate.
- The cell will lose its cleaning and defense functions.
- Over time, the cell may become toxic inside and may die.
- Thus, the Golgi is vital for processing, packaging, and cell survival.
Q7. A plant’s plastids get damaged in many leaf cells. Explain how this will affect food production and storage in the plant.
Answer:
- Plastids are key in plants.
- Chromoplasts with chlorophyll are crucial for photosynthesis.
- If they are damaged, light energy use will drop, and food making will fall.
- Leucoplasts store starch, oils, and proteins. Their damage reduces storage.
- The plant will make less glucose and store less reserve food.
- Growth may slow, and leaves may wilt due to low energy.
- Overall, both production and storage are impaired.
Q8. A white blood cell engulfs a bacterium. Using only the given organelles, explain step-by-step how the cell destroys it.
Answer:
- The cell wraps the bacterium into a vesicle inside the cytoplasm.
- A lysosome moves to this vesicle.
- The lysosome fuses with it and releases digestive enzymes.
- These enzymes break down the bacterium into simpler substances.
- Useful parts may be reused by the cell.
- The waste is sent to the cell membrane and thrown out.
- Lysosomes thus act as defenders and cleaners.
Q9. A student gets a small cut that heals in a few days. Explain how cell division helped. Also, say why meiosis is not used here.
Answer:
- Healing needs new cells to replace damaged ones.
- Mitosis makes two identical daughter cells from one mother cell.
- These new cells fill the gap and repair the tissue.
- Mitosis keeps the chromosome number the same, so function stays normal.
- Meiosis is for making gametes and halves the chromosome number.
- Gametes are not needed in repair, so meiosis is not used.
- Thus, mitosis supports growth and healing.
Q10. Imagine gametes were formed by mitosis instead of meiosis. What problems would occur after fertilization? Explain using chromosome number.
Answer:
- Meiosis normally makes gametes with half the chromosome number.
- If gametes formed by mitosis, they would have the full number.
- During fertilization, the two full sets would add up.
- The new cell would have double the normal chromosomes.
- With each generation, the number would keep doubling.
- This would disrupt normal development and survival.
- So, meiosis is essential to keep chromosome number constant.