All cells have the same chemical composition.Cells contain the hereditary information which is passed from cell to cell during cell division.All energy flow takes place within the cells.All cells arise from the pre-existing cells by division method and this was given by Rudolf Virchow.The cell is said to be the basic structural and functional unit of living things.Every living organism is made up of cells.In 1839, two scientists named Schleiden who was a German botanist, and Schwann who was a British zoologist, announced the cell theory. These tissues perform specific functions. The different types of cells are grouped to form tissues. In the human body, different types of cells are present such as hepatocytes in the liver, nephrons in the kidney, neurons in the brain, etc. Robert Hooke was the scientist who first discovered cells in a piece of cork. All organisms including plants and animals are made up of one or more cells and all that cells come from pre-existing cells. Cells are capable of independent existence and performing essential functions of life. The cell is the smallest, basic structural, and functional unit of living things hence it is generally referred to as ‘building blocks of life. Mastering Class 11 English Chapter 8: Cell the Unit of Life - Notes, Question and Answer, and Tips for Success (ii) Acrocentric chromosome: Chromosome in which the centromere is situated close to its end forming one extremely short and one very long arm. (i) Mesosome: Differentiated form of cell membrane in prokaryotes which are essentially infoldings of cell membrane. It helps in digestion of food particles, other foreign bodies, old worn-out organelles of cell often resulting in death of cell hence are referred as suicidal bags of cell.Īns. These enzymes when released from lysosomes bring about breaks down of various cytoplasmic structures. Lysosomes are sac-like structures bounded by a single membrane which contains several digestive enzymes. Why are lysosomes called “suicidal bags”?Īns.
(b) Site for synthesis of ribosomal RNA (rRNA): Nucleolus is the site for synthesis of ribosomal RNA (rRNA)ġ0. (a) Major site for synthesis of lipid: Smooth endoplasmic reticulum is responsible for synthesis of lipids. (b) Site for synthesis of ribosomal RNA (rRNA)Īns. Name the organelles responsible for the respective functions. (v) It prevents cell contents from drying up.ĩ. (iv) It allows transport of various substances to & from the cell. (iii) It protects delicate plasma membrane present below it. (i) It provides a definite shape to the cell. What are the main functions of cell wall? (ii) Ribosome is known as the protein factory of the cell.Ĩ. (i) Rudolf Virchow first explained that cell arise from pre-existing cells. (ii) Which organelle is known as the protein factory of the cell?Īns. (i) Who first explained that cells arise from pre-existing cells? Chloroplasts are present in plant cells only while mitochondria are present in both plant and animal cells. Mitochondria and chloroplasts are the two semi-autonomous cellular organelles present in eukaryotic cells. Name semi-autonomous cellular organelles present in eukaryotic cells.Īns.
In human beings, the membrane of the erythrocyte has approximately 52% protein and 40% lipids.Īns. What is the composition of plasma membrane of human erythrocyte?Īns. Anton Von Leeuwenhoek first saw and described a live cell.Ĥ. Who first saw and described a live cell?Īns. Mitochondria is known as the powerhouse of the cell.ģ. Which organelle is called the powerhouse of the cell?Īns. Totipotency is the ability of a single cell to divide and produce all the differentiated cells in an organism.Ģ.
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