Mitochondria and chloroplasts are two important organelles in a plant cell. Class 9
Mitochondria and chloroplasts are two important organelles in a plant cell. Class 9
Question 1.
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. Class 9
Answer:
Similarities
| Feature | Mitochondria | Chloroplast |
| Number of membrane | Double Membrane bound | Double Membrane bound |
| Own DNA | Yes | Yes |
| Own ribosome | Yes | Yes |
| Can make some own proteins | Yes | Yes |
| Semi-fluid interior | Yes (matrix) | Yes (stroma) |
Both mitochondria and chloroplasts have their own DNA and ribosomes, which suggests they share an evolutionary history with ancient bacteria that were absorbed into early eukaryotic cells.
Differences
| Feature | Mitochondria | Chloroplast |
| Function | Cellular respiration — breaks down glucose to release energy (ATP) | Photosynthesis — uses sunlight to make glucose (food) |
| Energy direction | Releases energy | Stores energy |
| Present in | Both plant and animal cells | Only plant cells (and some algae) |
| Pigment | None | Contains green chlorophyll |
| Inner membrane | Folded into cristae | Has disc-shaped structures containing chlorophyll in stroma |
| Raw material | Glucose + oxygen | CO2 + water + sunlight |
| Product | ATP (energy) + CO2 + water | Glucose + oxygen |
In simple words: Mitochondria burn food to release energy; chloroplasts use sunlight to make food.
Question 2.
Which of the following pairs of cell organelles contains DNA? Class 9
(i) Chloroplasts, Ribosomes
(ii) Mitochondria, Nucleus
(iii) Golgi bodies, Ribosomes
(iv) Nucleus, Lysosomes
Answer:
Option (ii) - Mitochondria, Nucleus
Explanation:
- The nucleus contains chromosomes, which are made of DNA
- Mitochondria have their own DNA (circular, like bacterial DNA)
- Chloroplasts also have their own DNA - but that option is not in the choices
- Ribosomes do not contain DNA - they contain RNA and proteins
- Golgi bodies and lysosomes do not contain DNA