Cell The Unit of Life Test - 87

Correct option: C
Explanation for correct option: 

• The smooth endoplasmic reticulum (SER) is a part of the endoplasmic reticulum which does not possess ribosomes studded on its membrane.
• It is involved in the detoxification of many poisons and drugs such as drugs, aspirin, insecticides (DDT), petroleum products and pollutants and converting them to safer water-soluble products. 
• Due to its function of detoxification, SER is abundant in the liver.  

The centrosome is the region present adjacent to the nucleus and in the cytoplasm which contains centrioles. It is also called the microtubule organizing center of the cell. Centrosome helps in cell division in animal cells. The centrosome is absent in plant cells. Mitochondria, ribosomes and, lysosomes are present in both animal cells as well as in plant cells. 
Thus, the correct answer is option A. 

When the organization of a cell is destroyed the lysosomes burst with leakage of several hydrolytic enzymes which further leads to cell lysis. The hydrolytic enzymes of lysosomes are capable of digesting itself along with the other structural biomolecules of a cell. These are also known as "suicidal bags".
So, the correct answer is option B.

• Plastids are cytoplasmic organelles found only in plant cells.
• Leucoplasts are colourless plastids and mainly help in the storage of food compounds like starch, proteins and oil drops. Such colourless plastids are present in underground roots, stems.

Thus, the correct answer is (A).

Mitochondria use molecular oxygen to oxidise the carbohydrates and fats (lipids) present in the cell to carbon dioxide and water vapour. Oxidation releases energy in the form ATP which is used in different other metabolic pathways. Since, the mitochondria synthesise, energy-rich compounds (ATP), they are known as powerhouses of the cell.  
The Golgi body has the main function of modifying, sorting and packaging of various cellular secretions. It packages materials synthesised in the cell and dispatches them either to intracellular targets such as plasma membrane and lysosomes or extracellular targets (e.g., zymogens). Golgi bodies form the part of the cellular endomembrane system. So, the correct answer is option C.

Cell organelle marked as S is 'smooth endoplasmic reticulum'.  Organelle labelled as R is the rough endoplasmic reticulum which consists ribosomes labelled as Q, known as protein factory of the cell. Smooth endoplasmic reticulum is involved in the formation and transportation of lipids. Thus, the correct answer is option A.

Lysosomes are the smallest organelles in the cell. It contains a hydrolytic enzyme that digests the wastes and other bad organelles. When the cell dies, the lysosomes digest the dead cell. Without lysosomes, living organisms would become filled with dead cells. Thus, lysosomes are called as suicidal bags.
Mitochondria play host to one of the most important processes in your body: cellular respiration. Taking in glucose and oxygen, mitochondria produce energy, which they capture and package as energy-rich molecules of ATP.
The ribosome is the structure within living cells that manufactures proteins. It attaches to a strand of messenger RNA and wriggles along it, 'reading' the genetic code as it goes and translating the message into a lengthening chain of amino acids.
The chloroplast is called as the kitchen of the cell, as the food is prepared in this part of the cell. The chloroplast is the cell organelle which gives a green colour to the leaf. It produces glucose and then it is converted into sucrose and then transported to whole the plant body or wherever required.
Endoplasmic reticulum (ER) is known as the circulatory system of the cell because it transforms poisons, waste and toxic substances to harmless products. Rough ER has ribosomes which construct proteins; Smooth ER which has no ribosomes processes lipids and carbohydrates.
So, the correct answer is option A.

The bacterium contains cell wall around the cell membrane. It works as a protective layer against the external environment. This layer is rigid than the cell membrane. As the bacterium is put in the hypo-osmotic environment, water enters the cell via endosmosis and the cell swells up. The internal turgor increases due to this and it puts pressure on the bacterial wall but it does not burst as the cell wall is rigid and gives support.

• The nucleoplasm is a viscous fluid enclosed in a double-walled membrane of the nucleus. 
• The mitochondrion is a membrane-bound organelle found in most eukaryotic cells. These structures are sometimes described as "the powerhouse of the cell" because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.
• Chloroplasts are organelles, specialized subunits, in plant and algal cells. Their main role is to conduct photosynthesis, where the photosynthetic pigment chlorophyll captures the energy from sunlight, and stores it in the energy storage molecules ATP and NADPH while freeing oxygen from water.
• Ribosomes are the protein builders or the protein synthesizers of the cell. They are like construction guys who connect one amino acid at a time and build long chains. Ribosomes are special because they are found in both prokaryotes and eukaryotes. Thus, the correct answer is option C.

A lysosome is a small vesicle membrane-bound cell organelle found in most animal cells. It contains hydrolytic enzymes capable of breaking down cell debris, wastes, foreign particles, dead or weak organelles and sometimes its own cells. Thus, lysosomes act as the waste disposal system of the cell by digesting unwanted materials in the cytoplasm, both from outside of the cell and obsolete components inside the cell. For this function, they are referred to as "cell's combination food processor and garbage disposer".