THE PROPERTIES AND FUNCTIONS OF THE CELL
CONTENT
- The Cell’s Reactions to its Environment
- Movement
- Reproduction
The Cell’s Reactions to its Environment
The protoplasm of plant and animal cells is irritable. It can detect and respond to the changes in their environment. Any change in conditions which is enough to produce a change in the activities of an organism or its part is called a stimulus.
Types of Responses
The three responses of the cell to its environment are tactic, nastic and tropic responses.
A. Tactic Responses (Taxism)
It is a response made by a whole organism or its freely locomotive parts in response to an external stimulus. Types of tactic responses are:
(i) Phototactic (Phototaxis): response to variation and intensity of light e.g. in free swimming Euglena, Chlamydomonas etc.
(ii) Chemotactic (Chemotaxis): response to the presence of chemical substances e.g. chemotactic movement of Amoeba away from an acidic environment.
(iii) Aerotactic (Aerotaxis): response to the source of oxygen
(iv) Osmotactic (Osmotaxis): response to variation in osmotic concentration
B.
- NEW: Download the entire term's content in MS Word document format (1-year plan only)
- The complete lesson note and evaluation questions for this topic
- The complete lessons for the subject and class (First Term, Second Term & Third Term)
- Media-rich, interactive and gamified content
- End-of-lesson objective questions with detailed explanations to force mastery of content
- Simulated termly preparatory examination questions
- Discussion boards on all lessons and subjects
- Guaranteed learning