Fundamental Unit Of Life - MCQ Test (22-11-2017) - Class 9 MCQ

RBC is called as red blood corpuscles. Red Blood Cells in mammals anucleate when mature i.e. they do not contain a nucleus. This is so that the cell has maximum space for haemoglobin.

Mitochondria iscalled as power house of the cell because it contains enzymes for cellular respiration. During cellular respiration, energy is released which is stored in the form of ATP.

Answer:
The correct answer is C: Purkinje.
Explanation:
- The term "protoplasm" was first used for living cells by Jan Evangelista Purkinje, a Czech anatomist and physiologist, in the early 19th century.
- Purkinje was studying the structure and function of cells, particularly in relation to the nervous system.
- He observed that cells, including nerve cells, contained a jelly-like substance that he named "protoplasm."
- Purkinje's work on protoplasm laid the foundation for modern cell biology and our understanding of the fundamental unit of life.
- His use of the term "protoplasm" helped to distinguish living cells from non-living matter and contributed to the development of the cell theory.
- The term "protoplasm" is still used today to refer to the living material within cells, including the cytoplasm and nucleus.
- Other scientists, such as Robert Hooke, Leeuwenhoek, and Robert Brown, made significant contributions to the field of cell biology, but they did not use the term "protoplasm" to describe living cells.
Therefore, the correct answer is C: Purkinje.

Rudolf Virchow presented the idea in 1855 that every cell arises from another (pre-existing) cell. This was a addition to the cell theory that was proposed earlier by Matthias Jakob Schleiden and Theodor Schwann.

Animal cell that do not contain nuclei will also lack in chromosomes. Chromosomes are present inside the nucleus of a cell. Chromosomes contain information for inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules.

The full form of ATP is adenosine triphosphate. ATP is known as the energy currency of the cell. The energy required for various chemical activities is released by mitochondria. They contain enzymes for cellular respiration.

The passage of water from a region of higher water concentration to a region of lower concentration through a semi-permeable membrane is called osmosis. The movement of water across the plasma membrane is affected by the amount of substance dissolved in water.  

According to Thomas Henry Huxley, the protoplasm is the physical basis of life. It is the living substance inside in the cell that contains all the cell organelles. It is a thick fluid or jelly-like substance.

There are 26 chromosomes (13 pairs) in the cells of a frog. These chromosomes are present inside the nucleus of a cell. Chromosomes contain information for inheritance of features from parents to next generation in the form of DNA (Deoxyribo Nucleic Acid) molecules.

Mitochondria are called the powerhouses of the cell. The energy required for various chemical activities is released by mitochondria. They contain enzymes for cellular respiration. During cellular respiration, energy is released in the form of ATP (Adenosine triphosphate). The body uses energy stored in ATP.

Plastid is the largest cell organelle in a plant. It contains chlorophyll necessary for photosynthesis. Plastid is the site of manufacture and storage of important chemical compounds used by the plant cell.

The term protoplasm was coined by Johann Evangelist Purkinje in 1839. Protoplasm is the fluid medium inside a cell in which different cell organelles are present.

Protein synthesis involves formation of amino acid chain according to information present on the DNA. The ribosomes, which are present in all active cells, are the sites for the manufacture of proteins. The proteins manufactured by the ribosomes are sent to other organelles in the cell. Some proteins function as enzymes and hormones.

Plant cells have plastids. Plastids with coloured pigments impart colours to various plant parts. Green colour is provided by chloroplast and other colours (except white) are imparted by chromoplast.

Lysosome is called as the suicide bag of the cell as it contain enzymes for hydrolysis of all cell components in case of injury. It plays a minor role in cell death. It was discovered and named by Belgian biologist Christian de Duve. De Duve had termed the organelles as the "suicide bags" or "suicide sacs" of the cells. He received the Nobel Prize in Medicine in 1974 for his discovery.

Plant cells can be larger than animal cells. Size of an animal cell varies from 10 to 30 micrometers while that of a plant cell ranges from 10 to 100 micrometers. 

Mitosis is a part of the cell cycle where replicated chromosomes are separated into two new nuclei. During mitotic division, the number of chromosomes in the daughter cells remains the same. Therefore, a cell having 10 chromosomes will produce daughter cells that have 10 chromosomes each.

Both the statements are correct. Golgi apparatus consists of a system of membrane-bound vesicles. The proteins manufactured by the ribosomes are packed inside the vesicles. Endoplasmic Reticulum (ER) is absent in the red blood cells of mammals. Red Blood Cells in mammals anucleate when mature i.e. they do not contain a nucleus. This is so that the cell has maximum space for haemoglobin.

Lysosomes present in the cytoplasm of a cell contain very strong enzymes that can break down the organic wastes produced in the cell. They are called as garbage disposal system of the cell.

The largest cell in the human body is the nerve cell. A nerve cell forms the functional unit of nervous system in animals for control and coordination.

The rough Endoplasmic Reticulum (RER) has ribosomes attached to its surface. Ribosomes are the sites of protein manufacture. They are associated with the synthesis of proteins from amino acids.

Endoplasmic Reticulum: Function and Explanation
The endoplasmic reticulum (ER) is a complex network of membrane-bound tubules and sacs located within the cytoplasm of eukaryotic cells. It plays a crucial role in various cellular processes. The main functions of the endoplasmic reticulum include:
Synthesis of Proteins:
- The rough endoplasmic reticulum (RER) is studded with ribosomes, which are responsible for protein synthesis.
- The ribosomes on the RER synthesize proteins that are destined to be secreted from the cell or embedded in the cell membrane.
- These proteins are synthesized by the ribosomes and then transported into the lumen of the RER for further processing and modifications.
Synthesis of Lipids:
- The smooth endoplasmic reticulum (SER) is involved in the synthesis of lipids, including phospholipids, cholesterol, and steroid hormones.
- Lipids play essential roles in cellular processes such as membrane structure, signaling, and energy storage.
- The SER also detoxifies harmful substances by metabolizing drugs and toxins.
Processing and Packaging:
- The endoplasmic reticulum is responsible for the processing and packaging of proteins and lipids.
- The proteins synthesized on the RER undergo modifications, such as folding and addition of sugar molecules (glycosylation).
- These modified proteins are then packaged into vesicles and transported to their final destinations within the cell or outside of the cell through the secretory pathway.
Transfer of Hereditary Characters:
- The transfer of hereditary characters, such as DNA, is not a function of the endoplasmic reticulum. This process occurs through other cellular mechanisms, such as DNA replication, transcription, and translation.
Conclusion:
Based on the given options, the correct answer is B: (a) and (c) are correct. The endoplasmic reticulum is involved in the synthesis of proteins and lipids, as well as the processing and packaging of these molecules. It does not play a direct role in the transfer of hereditary characters.

Lysosomes are the reservoirs of hydrolytic enzymes. These enzymes help in waste disposal of the cell. Hydrolytic enzymes can hydrolyze the complete cell in case of injury.

Plastids are present only in plants cells. Chromoplasts and chloroplasts are coloured plastids whereas leucoplasts are colourless. Chloroplast contains chlorophyll which is essential for photosynthesis in plants. Plastids are absent in animal cells.

In animals cells, centriole is present in the centrosome. Centrioles are a very important part of centrosomes. Centrosomes or spindle pole bodies act as the microtubule organising centers in animal cells. They help in the movement of chromatids towards the opposite pole.

Lysosome is called as digestive bag as it contains hydrolytic enzymes that help in the digestion of food and hydrolysis of cell constituents. It is also called as "suicide bag".

The 'Cell theory' was proposed by Matthias Jakob Schleiden and Theodor Schwann. According to this theory, all living organisms are made up of cells. Rudolf Virchow also contributed to the Cell theory. He proposed that new cells arise from pre-existing cells. 

Adenosine triphosphate (ATP) is called as the energy currency of the cell. Energy produced by a cell during internal respiration is stored in the form of ATP molecules. ATP breaks into ADP and phosphate to produce energy during cellular processes.

Nucleolus is present in the nucleus of the cell. It is called as little nucleus of the cell.

When a cell is placed in a hypotonic solution, the cell swells up due to endosmosis of water molecules from the region of higher concentration to the region of lower concentration.