Life Cycle - Organisms (4A)
Post Lab 

  • Comparing cells, tissues, and organs.
  • Classifying different organisms.
  • cell
  • organ
  • tissue
  • worksheet

Students use a worksheet to compare cells, tissues, and organs.

SEM of human blood cells.



Higher plants and animals require more complex structures in order to maintain their bodily processes. Some structures found in plants are organs but these are difficult to compare with those of an animal. Such things as limbs on a tree and plant stems are organs but in the classical sense we only consider organs to be structures like the heart or brain. Just as tissues and cells grouped together to form a higher system, organs do the same. A group of organs working together to perform a task is called an organ system. An example of an organ system is the circulatory system which includes the heart, blood, blood vessels, and lymph vessels in the animal kingdom. In higher animals, there is an organ system for almost every life process that takes place.

An organism is considered the ultimate level of organization. At this level all other levels are working together to make the organism a complete living thing. Thus the definition of an organ system is: A system that is constituted to carry on the life processes by means of organs that are functionally independent but mutually dependent.

  1. Use the worksheet to review organs, tissues, and cells of a protozoa, a mushroom, a flower and a dog. Some protozoa have no organs and tissues. It just has one cell. The different organelles act as the center of activity. Protozoa are so small that they do not need organs to circulate food, fluid, or wastes. A mushroom is a multicellular fungus whose external features represent its reproductive organs. A dog has internal organs composed of different types of tissues, just like humans.

  [Back to Life Cycle Grid]  [Back to Organisms (4)]