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Important Questions from Cell: the Unit of Life A cell is the smallest unit of life.

Important Questions from Cell: the Unit of Life A cell is the smallest unit of life. It is the fundamental structural, functional, and biological unit of all living organisms that are known till now. Through the study and analysis of cell the unit of life and its components, we can ascertain the physiological and behavioural processes of living organisms in molecular terms. This is known as the physio-chemical approach. Additionally, the physio-chemical method of studying living organisms is known as reductionist biology. The following important question from chapter 7 cell the unit of life will enable you to have a thorough idea of the cell and its various components. Short Answer Questions

Ans. Cell theory states that all living organisms are composed of cells and are products of cells. It also suggests that all cells arise from pre-existing cells.

Ans. When molecules pass through membranes of cell the unit of life without the help of energy, it is known as passive transport. On the other hand, active transport is when molecules require energy to move from a lower concentration region to a higher concentration region.

Ans. Microbodies are membrane-bound tiny vesicles which contain several enzymes. These microbodies can be found in both plant and animal cells.

Ans. Functions of mesosomes include distribution of daughter cells, replication of DNA and facilitation of cell wall formation. Moreover, it also increases the total surface area and aids in respiration and excretion.

Ans. Mitochondria is known as the powerhouse of cell the unit of life as it manufactures cellular energy which is in the form of ATP or Adenosine triphosphate.

Ans. In some cases, the fragment of a chromosome is separated from the main body by a secondary constriction. It is known as a satellite chromosome.

Ans. Singer and Nicholson presented the fluid mosaic model, which shows the structure of the cell membrane as a mosaic of different components – protein, lipid bilayer, cholesterol, sugar. The ratio of each element varies as per cell type. Additionally, the semi-fluid nature of lipid enables the movement of protein. Long Answer Questions

Ans. Organisms which have prokaryotic cells are unicellular organisms such as bacteria, mycoplasma, blue-green algae etc. Prokaryotic cells have a wall which surrounds the cell membrane. The fluid matrix within the cell is called cytoplasm. Besides the genomic or single chromosome DNA located in a nucleoid, bacteria have a smaller DNA known as plasmids. It carries unique phenotypic characteristics. Prokaryotic cells of organisms like bacteria have three-layered cell envelope. The outermost layer is called glycocalyx, which can be a thick or thin layer. Next comes the cell wall, which acts as a protection and gives shape and structure to the organism. The final layer is the plasma membrane which is semi-permeable and interacts with the external world. The plasma membrane also contains the ribosome and inclusion bodies. The flagellum of a motile bacteria is made up of three parts – basal body, filament and hook. Other structures in bacteria are Pili which are elongated tubular structures composed of protein. Fimbriae resemble bristle-like structures. These two help the bacteria to function like hosting tissues, rocks in water, etc.

Ans. In contrast to prokaryotic cells, eukaryotic cells contain a nucleus which is membrane-bound. In addition to that, other membrane organelles can also be observed in the cytoplasm such as mitochondria, ribosomes, golgi bodies, chloroplasts, endoplasmic reticulum and so on. The cytoplasm is bound by a plasma membrane, which is semi-permeable and allows transportation of nutrients and fluids. Plant cells contain a cell wall in addition to plastids and a large central vacuole. Animal cells do not have these. Instead, it has centrioles which are not present in plant cells.

Ans. They are present in plant cells and carry pigments which give colour to plants. Plastids can be classified into three types based on the colour of a pigment – chloroplast, chromoplast and leucoplast. Chloroplasts have carotenoid pigments in addition to chlorophyll which helps in capturing light energy and thereby aid in the process of photosynthesis. Chromoplasts contain carotenoids pigments such as xanthophylls and carotene, which are responsible for red, yellow and orange colour. Leucoplasts have no colour. Its function is to store nutrients.    

Two functions of a cell which is a basic unit of life are that it aids in the transportation of essential nutrients and fluid, while also helping in the growth of living organisms through cell division.

In a eukaryotic cell, DNA is located in the nucleus, while in prokaryotic cells, DNA is located in a region which is referred to as the nucleoid.

The two types of cells are eukaryotic and prokaryotic cells.