Cell Structure And Functions Test - 2

i. Nucleus is a dense protoplasmic body that contains hereditary information for controlling cell activities as well as for transfer to next generation. The nucleus contains genetic material DNA, so it is needed for the inheritance of characters from one generation to another. ii. Smooth endoplasmic reticulum is specialised to synthesise lipids and steroids. iii. Ribosomes help in protein synthesis inside the cell. iv. Plasma membrane is the outer covering of most of the animal cells, living, ultra thin, elastic, semipermeable in nature. It provides the mechanical support and external frame to the protoplasm (cytoplasm + nucleus).
Hence, the correct sequence of the codes is P - 4, Q - 3, R - 1, S - 2.

The functions of endoplasmic reticulum are:

Detoxification: E.R helps in detoxification of many endogenous and exogenous compounds.

Glycogenolysis: Synthesis of glycogen occurs in the cytoplasmic matrix but the SER is involved in glycogenolysis.

Lipid synthesis: The SER is concerned with synthesis of lipid e.g. triglyceride. The membranes of SER also appear to be involved in the formation of lipoprotein
complexes. The SER is also involved in the initial stages of the breaking down of fatty acids.

The nucleoli present in the nucleus helps in the formation of ribosomes.

A. Lysosomes help in the destruction of foreign particles (bacteria and viruses).
B. Lysosomes help in intracellular digestion of food particles.
C. Ribosomes help in protein synthesis inside the cell.

Adenosine triphosphate (ATP) is known as the energy currency of a cell.

Mitochondria is known as the powerhouse of a cell. The energy required for various chemical activities needed for life is released by mitochondria in the form of ATP (Adenosine triphosphate) molecules.

Plastids are small bodies found free in the cytoplasm of most plant cells. They are absent in bacteria, fungi, cyanobacteria.

A. The endoplasmic reticulum (ER) is a large network of membrane bound tubes and sheets.
B. The function of the endoplasmic reticulum is to serve as channels for the transport of materials (especially proteins) between various regions of the cytoplasm or between the cytoplasm and the nucleus.
C. In the liver cells of the group of animals called vertebrates, smooth endoplasmic reticulum plays a crucial role in detoxifying many poisons and drugs.

Mitochondria produces energy through the cellular respiration and so, called as the power house of the cell. Ribosomes synthesise proteins. Golgi apparatus functions to sort and modify proteins and lipids. SER (smooth endoplasmic reticulum) helps in lipid and fat synthesis.

NAD is nicotinamide adenine dinucleotide.

Nucleolus is absent in prokaryotic cell.