Class 9 Science Chapter 5 MCQ

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

Nucleus is surrounded by two nuclear membranes was both forming a nuclear envelope. Golgi apparatus is a set of membrane bounded, fluid-filled visicles, vacuoles and flattened cisternae. Plastids are also membrane bound organelles but ribosomes moves freely in the matrix or remain attached to the endoplasmic reticulum.

Generally, inside the cell there exist a membranous network enclosing a fluid-filled lumen which almost fills up the intracellular cavity, called endoplasmic reticulum (ER). It is of two types: i)Rough Endoplasmic Reticulum with ribosomes attached on its surface for synthesizing proteins. Ii)Smooth Endoplasmic Reticulum which is without ribosome and is meant for secreting lipids.

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

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.

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

In prokaryotic cell nucleus is absent whereas in eukaryotic cell nucleus is present.

The undefined nuclear region is the cytoplasm of prokaryotic cells is called nucleoid. The prokaryotic cells consist of a single chromosome, which is direct content of the cytoplasm i.e., there is no nuclear membrane in a eukaryotic cell, the nuclear envelope separates the nucleus from the cytoplasm. The nuclear envelope contains many pores (the nuclear pores) and encloses the liquid ground substance, the nucleoplasm. Within nucleoplasm two types of nuclear structures are embedded-the nucleolus and chromatin material. The nucleolus may be one or more in number and is not bounded by any membrane. It is rich in protein and RNA (Ribonucleic Acid) molecules and acts as the site for ribosome formation, hence are also known as factory of ribosomes.

Viruses are an exception to cell theory.

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.