Class 9 Science Chapter 5 MCQ

Grana are stacks of membrane bounded flattened discoid sacs containing the molecules of chlorophyll.

Mitochondria are absent in bacteria and the red blood cells of mammals.

Here, are all the statements are correct. Hence, your answer will be option [D].

Lipid molecules in the cell are synthesized by the smooth endoplasmic reticulum present in the cell.

Camillo Golgi, discovered the revolutionary method of staining individual cell structures. This method is referred to as “Black reaction”. It uses weak solution of silver nitrate and is valuable in tracing the processes and most delicate ramifications of cells.

Vacuoles may be small or large. These are filled with liquid or sap and are membrane-bound organelles. In animal cells, vacuoles are smaller in size and lesser in number than in plant cells. In some plant cells, only one large vacuole is present. The major portion of a plant cell is occupied by vacuoles. The (approx. 90% in some cases) either may be contractile (can contract) or non-contractile. When the pressure of the contents of a contractile vacuole increases, it contracts and releases its contents. In unicellular organisms like Amoeba, food particles are present inside food vacuoles. But are not associated with locomotion. The main functions of vacuoles are 1.In animals, vacuoles are often associated with the maintenance of water balance. 2.They work in osmoregulation, i.e., the maintenance of internal pressure. 3.They store various substances including waste products.

The prokaryotic cells lack true nucleus and a circular DNA lies naked in the cytoplasm. The unidentified nuclear region of the cell is called nucleoid. The prokaryotic cell lacks chromosomes and nucleolus or nuclear membrane and nucleoplasm remains undifferentiated from the cytoplasm.

Here, are all the statements are correct. Hence, your answer will be option [D].

Osmosis is a spontaneous process where movement of solvent molecules occurs into a region of higher solute concentration from lower solute concentration through a partially permeable membrane, so as to tend to equalise the solute concentration on the two sides. When movement of the solvent takes place from outside to inside the all (inward movement) the process is endosmosis. It occurs in hypertonic solution and causes the swelling of cell. When the movement of solvent takes place from inside to outside of the cell (outward movement) the process is exosmosis. It occurs in hypertonic solution. It results the shrinkage of the cell. When the concentration of water both in the surrounding medium and in the cell is same, the solution in the surrounding medium is said to be isotonic and no movement of water molecules takes place.

Viruses are considered as an intermediate between living and non-living cells because they cannot metabolize and reproduce on their own. They can reproduce only when enters in a host’s body. They are an exception to all cell theory. A virus crystal is a collection of thousands of viruses. Viral crystal is a pore collection used for chemical studies.