Assertion. The fundamental organizational unit of life is the cell.
Reason. cells are enclosed by a plasma membrane composed of lipids and proteins
Answers
Answer:
Cell wall (Protective wall): Plants cells, in addition to the plasma membrane have another rigid outer covering called cell wall. The cell wall lies outside the plasma membrane. The plant cell wall is mainly composed of cellulose. It is a complex substance and provides structural strength to plant cells. When a living plant loses water through osmosis there is shrinkage or contraction of contents of the cell away from cell wall. This phenomenon is known as plasmolysis.
3. Nucleus (Brain of a cell): The nucleus has a double-layered covering called nuclear membrane. The nuclear membrane has pores which allow the transfer of material from inside the nucleus to its outside, i.e., to the cytoplasm.
The nucleus contains chromosomes, which are visible as rod-shaped structures only when the cell is about to divide. Chromosomes contain information for inheritance of features from parents to next generation in form of DNA [Deoxyribo Nucleic Acid) molecules. Chromosomes are composed of DNA and protein. Functional segments of DNA are called genes. The nucleus plays a central role in cellular reproduction.

Prokaryotic Cells: In some organisms like bacteria, the nuclear material is not enclosed by nuclear membrane and membrane bound cell organelle are absent. Such nucleus is called nucleoid and such cells are known as prokaryotic cell. Such cells have single chromosome.
Eukaryotic Cells: Cells having well defined nucleus and having membrane bound cell organelle is termed as eukaryotic cell. Such cells have more than one chromosomes.
4. Cytoplasm: The cytoplasm is the fluid content inside the plasma membrane. It also contains many specialised cell organelles. Each of these organelles performs a specific function for the cell.
5. Cell Organelles: Every cell has a membrane around it to keep its content separate from the external environment. The different components of cell perform different function and these components are called cell organelles.
(i) Endoplasmic Reticulum (ER) (Channels, Network for transport): The ER is a large network of membrane-bound tubes and sheets. It looks like long tubules or round or oblong bags.
Both A and R are true, and R is correct explanation of the assertion.