Question

A plant cell has all of the following organelles except:
A. Chloroplasts
B. Centrioles
C. Cell wall
D. Large central vacuole
E. Mitochondria

Answer 1

Anton van Leeuwenhoek was the first who saw and described a living cell. The cells possess the membrane-bound distinct structures called organelles which perform a different function which collectively contribute to the cell functioning. Plant cells differ from animal cells in an organelle that helps them in the division process. This organelle is a characteristic feature of animal cells only.

Complete step by step answer:
A. The chloroplasts are the cell organelles that are present in the cells of plants and many photosynthetic algae. Chloroplast absorbs the sunlight and conducts the process of photosynthesis from sunlight and carbon dioxide. It is responsible for the preparation of food in the form of glucose. These are abundantly present in leaves of plants, where the maximum photosynthesis takes place.
B. Centrioles are organelles specifically found in animal cells only. These are cylindrical in shape and are arranged perpendicularly to each other. These help in cell division by spindle fibre formation and separation of chromosomes. They are absent in plant cells as plants cells do not divide by spindle formation.
C. The cell wall is the outermost layer made up of cellulose and hemicellulose, found in plants. It is also found in some lower organisms. It plays the role of protection against mechanical damage and provides structural support to plants as it is rigid and solid.
D. Large central vacuole is also a characteristic feature of plant cells and occupies about 80 percent of the space in a plant cell. It contains a high amount of water that helps it to exert pressure on its wall called tonoplast and some dissolved solvents. It plays a major role in support, storage, protection, growth and waste disposal.
E. Mitochondria are a double membrane-bound organelle having an outer membrane and an inner membrane which divides its lumen into two aqueous compartments. The inner part of the mitochondria contains a fluid called matrix and inner membrane forms various finger-like extensions called cristae to increase the surface area. Mitochondria are the sites of aerobic respiration that produce energy in the form of ATP.
Therefore, the correct answer is option B.

Note: The cell organelles like chloroplasts and mitochondria contain their own circular DNA and ribosomes. By evolutionary evidence, it is believed that mitochondria, as well as chloroplast, existed as unicellular organisms, but due to the changing environment, both of these organelles couldn’t survive as discrete organisms and came into endosymbiont relationship with eukaryotic cells.