Latest questions in this category.
Cristae increase the area of the inner mitochondrial membrane, which contains enzymes associated with mitochondrial activity. Reducing cristae would reduce the membrane area available for oxidative phosphorylation and ATP generation.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Most chloroplasts of green plants occur in leaf mesophyll cells, where approximately 20–40 may occur per cell. Chloroplasts contain chlorophyll and carotenoids that trap light energy required for photosynthesis.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Cristae are infoldings that increase the surface area of the inner mitochondrial membrane, whose enzymes are associated with mitochondrial activity. Flattening them reduces this area. Matrix components such as circular DNA, RNA and 70S ribosomes need not be removed.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
The cytoplasm is the semi-fluid matrix and principal arena of cellular reactions. Ribosomes are non-membrane-bound RNA–protein particles occurring freely in the cytoplasm, on rough ER, and within mitochondria and chloroplasts.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Cristae identify X as a mitochondrion, while thylakoids and stroma identify Y as a chloroplast. Mitochondria perform aerobic respiration and generate ATP; chloroplasts trap light energy. Their circular DNA and 70S ribosomes support some protein synthesis within both organelles.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Chlorophyll occurs in the thylakoids, and stacks of thylakoids form grana, which are the sites of light reactions. Circular DNA, ribosomes and enzymes for carbohydrate and protein synthesis occur in the stroma and may remain present.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Lysosomes contain hydrolytic enzymes, while vacuoles contain water, sap, excretory products and other materials. Mitochondria possess inner-membrane cristae, whereas chloroplasts contain thylakoids arranged into grana.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Both mitochondria and chloroplasts contain circular DNA and 70S ribosomes, so those features alone do not distinguish them. Pigment-bearing thylakoids and enzymes for carbohydrate synthesis in the stroma identify the organelle as a chloroplast.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
The tonoplast transports several ions and other materials into the vacuole against concentration gradients. Loss of this function would prevent the vacuole from maintaining concentrations significantly higher than those in the cytoplasm.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Grana are the sites of the light reactions of photosynthesis, whereas the chloroplast stroma is the site of the dark reactions. Chlorophyll pigments are located in the thylakoids that form the grana.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
The thylakoid membrane encloses an internal space called the lumen. Thylakoids are flattened membranous sacs present within the chloroplast stroma.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
Food vacuoles in many cells, including protists, are formed when the cell engulfs food particles. They differ functionally from the contractile vacuole, which is involved in osmoregulation and excretion.
Ref: NCERT Class 11 Biology Chapter 8: Cell: The Unit of Life Mitochondria Plastids Ribosomes and Other Organelles
