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Q1. Leucoplasts mainly store:
Leucoplasts are colourless plastids that mainly store starch, oils, and protein granules. They are found in plant cells and serve as storage organelles. Unlike chloroplasts, leucoplasts do not contain pigments and are not involved in photosynthesis.
Q2. Plant cells usually have vacuoles that are:
Plant cells usually have very large vacuoles. These large vacuoles can occupy up to 50-90% of the cell volume. They store cell sap (water, minerals, sugars, and other substances) and help maintain turgidity and rigidity in plant cells.
Q3. Which substance is NOT stored in plant vacuoles?
DNA is NOT stored in plant vacuoles. DNA is stored in the nucleus, mitochondria, and chloroplasts. Vacuoles store organic acids, sugars, amino acids, and other dissolved substances. They do not store genetic material.
Q4. Boiled potato cup does not show osmosis because:
A boiled potato cup does not show osmosis because the cell membrane is destroyed by boiling. Since osmosis requires a selectively permeable membrane, boiling kills the cells and destroys the membrane, preventing the movement of water across it.
Q5. Water gathers in sugar or salt potato cups due to:
Water gathers in sugar or salt potato cups due to osmosis. The sugar or salt solution inside the potato cup has a higher solute concentration than the water outside. Water moves from the region of lower solute concentration (outside) to higher solute concentration (inside) through the selectively permeable membrane of potato cells.
Q6. Proteins are synthesised at:
Proteins are synthesised at ribosomes. Ribosomes are the sites of protein synthesis in the cell. They read the genetic code from mRNA and assemble amino acids into proteins. Ribosomes can be free in the cytoplasm or attached to rough ER.
Q7. The central vacuole in plant cells may occupy:
The central vacuole in plant cells may occupy 50-90% of the cell volume. It is the largest organelle in plant cells and is filled with cell sap. The large vacuole helps maintain turgidity, stores nutrients and waste products, and provides structural support.
Q8. Proteins for cell membrane are synthesised in:
Proteins for the cell membrane are synthesised in ribosomes on the rough endoplasmic reticulum (RER). These proteins are then transported to the Golgi apparatus for modification and packaging before being incorporated into the cell membrane.
Q9. Lipids for cell membrane are synthesised in:
Lipids for the cell membrane are synthesised in the smooth endoplasmic reticulum (SER). SER is also involved in the synthesis of steroids and the detoxification of drugs. The lipids produced are then transported to the Golgi apparatus for further processing.
Q10. Yellow and orange pigments are present in:
Yellow and orange pigments are present in chromoplasts. Chromoplasts are coloured plastids that contain pigments like carotene and xanthophyll. They are responsible for the colours of flowers, fruits, and leaves (e.g., tomatoes, carrots, and autumn leaves).
Q11. Vacuoles store:
Vacuoles store solid or liquid contents. They can store water, minerals, sugars, amino acids, organic acids, and sometimes solid materials like pigments and crystals. They act as storage sacs and help maintain the cell’s turgidity.
Q12. Plastids are similar in external structure to:
Plastids are similar in external structure to mitochondria. Both are double-membrane-bound organelles and contain their own DNA and ribosomes. They are involved in energy conversion—mitochondria in cellular respiration and plastids in photosynthesis.
Q13. Amoeba obtains its food by:
Amoeba obtains its food by endocytosis. It engulfs food particles by extending pseudopodia (false feet) around the food. The food is then enclosed in a food vacuole and digested. This process is also called phagocytosis.
Q14. If plasma membrane ruptures, the cell will:
If the plasma membrane ruptures, the cell will die. The plasma membrane maintains the integrity of the cell and controls the movement of substances in and out. If it ruptures, the cell loses its internal environment and cannot survive.
Q15. Golgi apparatus absence will affect:
The absence of the Golgi apparatus will affect packaging and transport of materials. The Golgi apparatus modifies, sorts, and packages proteins and lipids for transport to their final destinations. Without it, these materials would not be properly processed and delivered.
Q16. Which cell type has plastids?
Plant cells have plastids. Plastids are organelles found in plant cells and some algae. They are involved in photosynthesis (chloroplasts), storage (leucoplasts), and pigment storage (chromoplasts). Animal cells do not have plastids.
Q17. Vacuoles help plants mainly by:
Vacuoles help plants mainly by maintaining turgidity (stiffness). The large central vacuole filled with cell sap exerts turgor pressure against the cell wall, keeping the plant cells firm and providing structural support. This helps plants stand upright and maintain their shape.
Q18. If the organisation of a cell is destroyed, the cell will:
If the organisation of a cell is destroyed, the cell will stop functioning properly. Each organelle has a specific function, and the cell depends on the coordinated activity of all its parts. Without proper organisation, the cell cannot carry out its life processes.
Q19. Food vacuole in Amoeba contains:
The food vacuole in Amoeba contains consumed food items. After Amoeba engulfs food by endocytosis, the food is enclosed in a food vacuole. Digestive enzymes are released into the vacuole to break down the food into simpler substances.
Q20. Stroma is found inside:
Stroma is the fluid matrix found inside chloroplasts. It surrounds the thylakoid membranes and contains enzymes for the Calvin cycle (the dark reactions of photosynthesis). The stroma is similar to the matrix in mitochondria.
Q21. Coloured plastids are called:
Coloured plastids are called chromoplasts. They contain pigments like carotene and xanthophyll, which give colours to flowers, fruits, and leaves. Examples include the red colour of tomatoes, yellow of bananas, and orange of carrots.
Q22. Cell is the fundamental unit of life because:
The cell is called the fundamental unit of life because all life functions occur within it. The cell is the smallest structure that can perform all the activities necessary for life, such as nutrition, respiration, excretion, and reproduction.
Q23. Gamete formation involves:
Gamete formation (sperm and egg cells) involves meiosis. Meiosis is a type of cell division that reduces the chromosome number by half, producing haploid gametes. This ensures that when two gametes fuse during fertilisation, the resulting zygote has the correct diploid number of chromosomes.
Q24. Which pigment is present in chloroplasts?
Chlorophyll is the pigment present in chloroplasts. It is responsible for the green colour of plants and is essential for photosynthesis. Chlorophyll absorbs light energy (mainly blue and red light) and converts it into chemical energy.
Q25. How many main types of plastids are there?
There are three main types of plastids: chloroplasts (green, for photosynthesis), chromoplasts (coloured, for pigment storage), and leucoplasts (colourless, for storage of starch, oils, and proteins). Each type has a specific function in plant cells.
Q26. Vacuole in Amoeba is called:
The vacuole in Amoeba is called a contractile vacuole. It is responsible for expelling excess water and wastes from the cell. Amoeba lives in freshwater, where water constantly enters the cell by osmosis. The contractile vacuole pumps out this excess water to prevent the cell from bursting.
Q27. Respiration is a function performed by:
Respiration is a function performed by cells. In cells, mitochondria carry out aerobic respiration to release energy from glucose. All living cells perform respiration to generate ATP, which is used for various cellular activities. Organs, tissues, and organ systems are made of cells that perform this function.
Q28. Besides chlorophyll, chloroplasts also contain:
Besides chlorophyll, chloroplasts also contain yellow or orange pigments (carotenoids). These pigments absorb light in different wavelengths and protect chlorophyll from damage by excess light. They also contribute to the colour changes seen in autumn leaves.
Q29. Vacuoles provide ________ to plant cells.
Vacuoles provide turgidity and rigidity to plant cells. The large central vacuole filled with cell sap exerts turgor pressure against the cell wall, keeping the cells firm. This helps plants maintain their shape and stand upright.
Q30. Vacuoles are:
Vacuoles are storage sacs. They store water, minerals, sugars, amino acids, organic acids, and sometimes pigments. They can also store waste materials and help maintain the cell’s osmotic balance.
Q31. Vacuoles in unicellular organisms help in:
Vacuoles in unicellular organisms (like Amoeba) help in expelling excess water and wastes. Contractile vacuoles actively pump out excess water that enters the cell by osmosis. This prevents the cell from bursting and maintains osmotic balance.
Q32. Osmosis is related to movement of:
Osmosis is related to the movement of water. It is the net movement of water molecules from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration) through a selectively permeable membrane. It does not involve the movement of solutes.
Q33. Vacuoles in plant cells are filled with:
Vacuoles in plant cells are filled with cell sap. Cell sap is a solution of water, minerals, sugars, amino acids, and other dissolved substances. It gives the vacuole its function in storage and maintaining turgidity.
Q34. Chromoplasts containing chlorophyll are called:
Chromoplasts containing chlorophyll are called chloroplasts. Chloroplasts are green plastids that carry out photosynthesis. They contain chlorophyll, which absorbs light energy. Other chromoplasts contain different pigments (carotenoids) and are not involved in photosynthesis.
Q35. Plastids are present only in:
Plastids are present only in plant cells (and some algae). They are not found in animal cells, fungal cells, or bacterial cells. Plastids are involved in photosynthesis (chloroplasts), storage (leucoplasts), and pigmentation (chromoplasts).
Q36. The cell is called the basic structural unit because it:
The cell is called the basic structural unit because it forms the structure of all living organisms. Cells are the building blocks of life. They are arranged into tissues, which form organs, which form organ systems, and ultimately the organism.
Q37. The cell is called the basic functional unit because it:
The cell is called the basic functional unit because it performs all life functions. All activities essential for life—nutrition, respiration, excretion, reproduction, and growth—occur at the cellular level. The cell is the smallest unit that can carry out these processes.
Q38. Potato cup A is necessary to:
Potato cup A (without sugar or salt) is necessary to show a control experiment. It demonstrates that water movement only occurs when there is a concentration difference. In the control, no water movement is observed because the solutions inside and outside are the same.
Q39. Which organelle is known as powerhouse of the cell?
Mitochondria are known as the “powerhouse of the cell” because they produce energy in the form of ATP through cellular respiration. They are the sites of aerobic respiration, where glucose is broken down to release energy. This energy powers all cellular activities.
Q40. Which two organelles contain their own genetic material?
Plastids and mitochondria contain their own genetic material (DNA) and ribosomes. This supports the endosymbiotic theory, which suggests that these organelles were once free-living bacteria that were engulfed by eukaryotic cells. They can replicate independently within the cell.
Q41. The internal fluid material of chloroplast is called:
The internal fluid material of chloroplast is called stroma. It is the matrix that surrounds the thylakoid membranes inside the chloroplast. The stroma contains enzymes for the Calvin cycle (the dark reactions of photosynthesis).
Q42. Which cell division is required for growth and repair?
Mitosis is the cell division required for growth and repair. It produces two identical daughter cells with the same number of chromosomes as the parent cell. Mitosis allows organisms to grow, replace worn-out cells, and repair damaged tissues.
Q43. Which organelle stores starch?
Leucoplasts store starch. They are colourless plastids found in plant cells that store starch, oils, and proteins. Amyloplasts are a type of leucoplast that specifically store starch (e.g., in potato tubers).
Q44. Cell structure and function depend on:
Cell structure and function depend on the organisation of membrane and organelles. The arrangement and interaction of organelles within the cell determine what functions the cell can perform. Different types of cells have different organelles to carry out specific functions.
Q45. Like mitochondria, plastids also contain their own:
Like mitochondria, plastids also contain their own DNA and ribosomes. This allows them to make some of their own proteins and replicate independently. This is evidence for the endosymbiotic theory, which proposes that plastids and mitochondria originated from free-living bacteria.
Q46. Lysosomes are called suicide bags because they:
Lysosomes are called suicide bags because they digest their own cell when it gets damaged or becomes old. The lysosomes burst and release digestive enzymes, breaking down the entire cell. This self-destruction is a form of programmed cell death.
Q47. Vacuoles in animal cells are generally:
Vacuoles in animal cells are generally small-sized or sometimes absent. Animal cells may have small, temporary vacuoles for storage or transport, but they do not have the large central vacuole found in plant cells. The absence of a large vacuole is one of the differences between plant and animal cells.
Q48. Colourless plastids are known as:
Colourless plastids are known as leucoplasts. They are found in plant cells and are involved in the storage of starch, oils, and proteins. Leucoplasts do not contain pigments, so they are colourless. They are found in non-photosynthetic parts of plants like roots and tubers.
Q49. Internal organisation of chloroplast consists of:
The internal organisation of chloroplast consists of numerous membrane layers. Chloroplasts have a double outer membrane and an internal system of thylakoid membranes (stacked into grana). These membranes contain chlorophyll and are the site of the light reactions of photosynthesis.
Q50. Chloroplasts are important for:
Chloroplasts are important for photosynthesis. They contain chlorophyll, which captures light energy and converts it into chemical energy. During photosynthesis, carbon dioxide and water are converted into glucose and oxygen. This process is essential for the survival of plants and for the oxygen supply on Earth.