Class 9 Science Chapter 5 MCQ

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

The Golgi apparatus is involved in formation of lysosome. Lysosomes are simple, tiny spherical sac-like structures evenly distributed in the cytoplasm each lysosome is surrounded by a double membrane and contains powerful enzymes capable of digesting or breaking down all organic material. These enzymes are made by rough endoplasmic reticulum. They perform following functions in our body: i)They help in breaking down or digesting large molecules of the cell. ii)They help in a defence against bacteria and viruses. iii)During starvation, lysosomes act on their own cellular organelles and digest them. This results in cell death. The lysosomes are also called suicide bags or demolition squads of the cell.

In 1938 Schleiden proposed the idea that plants consist of cells. Later in the year 1839, Schwann independently asserted that all animals and plants are made up of cells. This joint finding forms the basis of cell theory. The cell theory was refined further in 1855, when R. Virchow presented the idea that all cells arise from pre-existing cell. His amorphism was (Omnis Cellula-e-Cellula).

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

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.

Plant cells, in addition to the plasma membrane, have another rigid rotor covering called the cell wall. The cell wall lies outside the plasma membrane. The plant cell wall is mainly composed of cellulose. Cellulose is a complex substance and provides structural strength to plants. Bacteria is not a plant therefore its cell wall is made up of “Peptidoglycan”.

In nucleoid, its DNA content is equal to a single DNA molecule. Generally, in nucleus, its DNA content is equal to two or several DNA molecules.

Smooth endoplasmic reticulum in liver cells of vertebrates helps in detoxification. It metabolises various toxic or poisonous substances such as drugs, aspirin, insecticides (DDT), petroleum products and pollutants. These toxic substances make their entry in animal’s body through food, air or water.

Lysosomes are simple, tiny spherical sac-like structures evenly distributed in the cytoplasm each lysosome is surrounded by a double membrane and contains powerful enzymes capable of digesting or breaking down all organic material. These enzymes are made by rough endoplasmic reticulum. They perform following functions in our body: i)They help in breaking down or digesting large molecules of the cell. ii)They help in a defence against bacteria and viruses. iii)During starvation, lysosomes act on their own cellular organelles and digest them. This results in cell death. The lysosomes are also called suicide bags or demolition squads of the cell.

The movement of water molecules through selectively permeable membrane along concentration gradient is called osmosis. It is the passage of water from region of high-water concentration through semipermeable membrane to a region of low water concentration (only through semipermeable membrane). Unicellular freshwater organisms and most plant cells tend to gain water through osmosis. Absorption of water by plant roots is also an example of osmosis.