Class 9 Science Chapter 5 MCQ

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

Golgi apparatus is absent in bacteria blue and green matches firms and red blood cells of mammals and other animals

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

Chloroplasts are present in green algae and higher plants. They have a green pigment called chlorophyll and they are involved in the photosynthesis of food. Therefore, they are also known as the ‘kitchens of the cells’. Each chloroplast is bounded by two-unit membranes like the mitochondria. It shows two distinct regions: i)Grana are the main functional units of chloroplast. They are stacks of membrane bounded, flattened discoid sacs (called thylakoids) containing the molecules of chlorophyll. ii)Stroma is the homogeneous matrix in which grana are embedded. It contains a large variety of photosynthetic enzymes, starch grains DNA and ribosomes.

Other than nucleus mitochondria contains DNA and are able to synthesise their own proteins they are regarded as semi-autonomous organelles.

Endocytosis is the ingestion of material by the cells through their plasma membrane. It is a collective term that describes three similar processes “phagocytosis” (cell eating), “potocytosis” (cell drinking) and receptor-mediated endocytosis. These processes are pathways to specifically internalise solid particles, small molecules and ion, and macromolecules, respectively. All of them require energy, so they may be regarded as different forms of active transport. Out of these phagocytosis is the common method of feeding among the Protozoa (e.g., Amoeba) and lower “Metazoa” (e.g., sponges). In pseudopodial movement the phagocyte enguls the particle lysosomes, join with the vacoule containing ingested particle and pour their contents into the vacoule to destroy the particle.

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].

When a cell is immersed in hypertonic (very concentrated) solution, water diffuses out of the cell by the process of osmosis. This is because there is a lower concentration of water outside the cell. Although water molecules pass the cell membrane in both direction but more amount of water goes out of the cell than the amount of water which enters it. As a result of this the cell shrinks. This process is called exosmosis. If exosmosis continues in a plant cell, the cytoplasm appears to be shrunken. This is called plasmolysis and the cell is said to be plasmolysed.

Chromosomes are thread like structure as usually present in the nucleus which becomes visible only during cell division. Each chromosome is made up of two components. i)Deoxyribonucleic acid (DNA) ii) Proteins (e.g. histones and acidic proteins) These consists of two (unreplicated) or four (duplicate) arms and a primary constriction or centromere which gives them a particular shape due to its position. The paired condition of chromosome is called diploid and unpaired chromosome are said to be haploid.