NCERT Solutions Class 8th Science Chapter – 8 Cell Structure and Functions Notes

• Roots, stems, leaves and flowers are the organs of plants.

• Hands, feet, legs, heart, kidney etc. are the organs of animals.

• All organs are made up of tissues which in turn are made up of cells.

• Though organisms differ in shape and size, these are all made up of a basic unit called cells.

• Cells present in living organism, differ in numbers, shape and size.

• Bacteria (PPLO) has the smallest cell size of 0.1 microns. Ostrich egg has the largest cell size of 170 mm.

• The shape of cells varies from spherical, cuboidal, columnar to long and branched types.

• Some cells have an irregular shape, i.e., Amoeboid shape, in case of amoeba.

• There are unicellular organisms (bacteria) as well as multicellular organisms (plants and animals).

• Each cell has smaller components, called organelles. Some of these are common to different cell types. Each organelle has its own specific function.

• The single cell of unicellular organisms performs all the basic functions, i.e., performed by a variety of cells in multicellular organisms.

• the cell membrane
• cytoplasm which contains smaller components called organelles, and
• the nucleus.

• Nucleus is separated from the cytoplasm by a nuclear membrane.

• Nucleus acts as a control centre for all the activities of the cell.

• Nucleus contains some smaller spherical body, i.e., nucleolus and threadlike structure, i.e., chromosomes.

• The chromosomes carry genes that help in inheritance or transfer of characters from parents to the offspring.

• Nucleoplasm is the liquid material of the nucleus.

• Cells without a well-organised nucleus, i.e., lacking a nuclear membrane, Eire called prokaryotic cells.

• Plant cells differ from animal cells in having an additional layer around the cell membrane termed as the cell wall.

• Coloured organelle, i.e., called plastids, are found in the plant cells only. Green plastids containing chlorophyll are called chloroplasts.

• Plant cell has a big central vacuole unlike a number of small vacuoles in animal cells.

• Cell is the basic structural and functional unit of all living organisms.

• Cell wall is a hard and rigid covering of plasma membrane and found in plant cells only.

• Chloroplasts are the green coloured plastids having chlorophyll, a winch is essential for photosynthesis.

• Chromosomes are a thread like structures found in the nucleus. It carries genes.

• Protoplasm is the viscous fluid inside the cell which provides living nature to it.

• Multicellular is the category of the organism like plants and animals, containing large number of cells.

• Nucleolus is a smaller, spherical and dense body inside the nucleus.

• Nucleus is the denser region of the cell and may be present at the centre of the cell.

• Organelle is one of the smaller components of a cell.

• Plasma membrane is a membrane around the cell, also called cell membrane.

• Plastids are the coloured organelles, that are found in plant cells only.

• Pseudopodia are the projections protruding out of the body of amoeba. These appear and disappear as amoeba moves.

• Unicellular is the category or organism like bacteria containing only a single cell.