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8th Std, , Science, 11. Cell Structure and Functions, Indicate whether the following statements are True or False ., Unicellular organisms have one-celled bodies. [T], Muscle cells are branched. [F], The basic living unit of an organism is an organ. [F], [T], , Amoeba has an irregular shape., , WN, , Make a sketch of the human nerve cell. What function do, , nervecells perform? i, : The nerve cell receives and transfers messages, Nucleus, there by helping to control and coordinate the :, , working of different parts of the body., , , , ANS, , 3. Write short notes on the following:, Human Nerve cell, , (i) Cytoplasm, (ii) Nucleus of a cell, (i) Cytoplasm. It is the fluid present between the cell membrane and the, , nucleus. Various components or organelles of cells, e.g.,, mitochondria, Golgi bodies, ribosomes, etc. are present in it. The, cytoplasm is made up of basic elements like C, H, O, N. They are, found in the form of chemical substances like carbohydrates,, proteins, and water. These substances are present in all the cells of, every organism., , (ii) Nucleus of a cell. The nucleus is a cell organelle in the middle of a, cell. It is dense and round. In the plant cells, the nucleus lies in the, periphery of the cell. The nucleus has a liquid protoplasm called, nucleoplasm. It is bounded by a nuclear membrane. The nucleus, controls the activities of the cells. It contains a network of fibrous, material called chromatin. The condensed chromatin is in the form, of fiber structures called chromosomes, which help in the, inheritance or transfer of characters from parents to the next, , generation., at., , 4. Which part of the cell contains organelles?, Cytoplasm., 4, Draw sketches of animal and plant cells and state three, , differences between them., Differences between plant cell and animal cells are, , Animal cell Plant cell, 1. Cell wall is absent in animal 1. Cell wall is present in plant, cell. cells., 2. Plastids are present., , 2. Plastids are absent., , 3. Vacuoles are of small size. 3. Vacuoles are of large size., , , , Cell wall., “ond, , , , , , , , , , 6. State a difference between eukaryotes and prokaryotes., , Differences between eukaryotes and prokaryotes are:, Eukaryotes Prokaryotes, , The organisms having cells witha 1. The organisms having cells, well-organized nucleus with a with nuclear material without, , nuclear membrane are called a nuclear membrane are, eukaryotes. called prokaryotes., 2. e.g. onion cells, cheek cells. 2. e.g. bacteria, blue-green algae., , a, , 1.

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7. Where are chromosomes found in a cell? State their function., Chromosomes are found in the nucleus of the cell, They carry gene, , and help in inheritance i.e., transfer of characters from the parents to, the offspring., , 8. “Cells are the basic structural units of living organisms.” Explain., As building cannot be built without bricks, in the same way living, organisms can not be formed without cells. The buildings are built of, similar bricks having different designs, shapes, and sizes. Similarly in, the living world, organisms differ from one another but all are made, , up of cells. Thus it is said that cells are the basic structural units of, living organisms., , 9. Explain why chloroplasts are found only in plant cells?, Chloroplasts contain chlorophyll which synthesizes food in plants by, the process of photosynthesis. No photosynthesis occurs in animals., So, they do not contain chloroplasts., , 10.Complete the following cross-word with the help of clues given., Across, , 1. This is necessary for photosynthesis., , 3. Term for component present in the cytoplasm., , 6. The living substance in the coil., , 8. Units of inheritance present on the chromosomes., , Down, , 1. Green plastids., , 2. Formed by a collection of tissues. :, , Single-celled organisms are called unicellular organisms. All the functions of unicellular organisms are carried out in the same cell. Examples, , are Amoeba, Paramecium., , , , Additional Questions and Answers, , 1., , What are cells?, Cells are basic structural units of living organisms., , What is a tissue?, A tissue is a group of similar cells performing a specific function., , What are the basic components of a cell?, The basic components ofa cell are the cell membrane, cytoplasm, and, nucleus., , What is a cell organelle?, Cells organelles are smaller components or parts of the cell present, inside it., , Name the membrane which binds the cells., Plasma membrane or cell membrane., , Name the liquid substance present in the cell., Protoplasm.