1.Is visible movement a defined characteristics of life?
2.Why are molecular movement needed for life?
3.Why are no specific organs are needed for taking in food ,exchange of gases for removal of wastages in single-celled organisms?
4.How do living things get their food ?
5.How is food carried along the digestive tract in aur body?
6.How many pairs of salivary gland are located in our body?and where they are located?
Answer 1)
Movement is a characteristic of life, but its not the only characteristic which confirms life. Non living things like vehicles show visible movement while living things like plants are stationary. So., just by visible movement we cannot define life.
Answer 3)
No specific organs are needed by the unicellular organisms as they are single cells performing all the functions necessary for life. They do not have complex structures and division of labor to perform the body functions.
Answer 4)
Living things get food by various means.
Autotrophs: Some of the living organisms are autotrophic, i.e., they make their own food from simple substances. Example : plants.
Heterotrophs: Some of the living organisms are heterotrophic, i.e., they take up food prepared by autotrophs. Example: humans.
Saprophytes: Some living organisms take up food from dead and decaying matter. Example Fungi.
