Study Materials

NCERT Solutions for Class 9th Science

 

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Chapter 5. The Fundamental Unit of Life

Chapter Review

 

 

 

Chapter Review:


  • The fundamental organisational unit of life is called cell.
  • Cells were first discovered by Robert Hooke in 1665.
  • The movement of water molecules through such a selectively permeable membrane is called osmosis.
  • The plasma membrane is flexible and is made up of organic molecules called lipids
    and proteins.
  • Nucleus is a largest cell organelle which consists inside the cell. Nuclei are found in all eukaryotic cells. It contains chromatin. Nucleus is a largest cell organelle which consists inside the cell. Nuclei are found in all eukaryotic cells. It contains chromatin. 
  • Cellulose is a complex substance and provides structural strength to plants.
  • The nucleus has a double layered covering called nuclear membrane.
  • Functional segments of DNA are called genes.
  • Mitochondria are known as the powerhouses of the cell.
  • ATP is known as the energy currency of the cell.
  • The internal organisation of the plastids consists of numerous membrane layers embedded in a material called the stroma.
  • Most plant cells have large membranous organelles called plastids, which are of two types – chromoplasts and leucoplasts.
  • Chromoplasts that contain chlorophyll are called chloroplasts and they perform photosynthesis.
  • Most mature plant cells have a large central vacuole that helps to maintain the turgidity of the cell and stores important substances including wastes.
  • If the medium surrounding the cell has a higher water concentration than the cell is known as hypotonic solution.
  • If the medium has exactly same water concentration than the cell is known as isotonic solution.
  • If the medium surrounding the cell has a lower concentration then the cell is known as hypertonic solution.

 

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Chapter Contents: