Bio 1.2 - processes of life in unicellular organisms

chapter A2.2.7

unicellular organism

An organism that contains all cells which perform all necessary functions for life.

Paramecium

a ciliated protozoan

Chlamydomonas

a photosynthetic green alga

What are the key functions for life?

“MR H GRENM": Movement, Response to Stimuli, Homeostasis, Growth, Reproduction, Excretion, Nutrition, Metabolism

metabolism

the sum of all chemical reactions in an organism

nutrition

obtaining and processing nutrients needed for survival

two ways organisms obtain nutrition

• autotrophs (produce their own organic compounds/ food from inorganic compounds, e.x. plants)

• heterotrophs (obtains nutrients by consuming other organisms, e.x. humans)

reproduction

the process by which organisms produce new individuals/ offspring to ensure the survival of their species

asexual reproduction + examples

organisms produce genetically identical offspring

e.x. hydras (cloning), binary fission

sexual reproduction + examples

involves genetic recombination

e.x. fusion of male and female gamete, conjugation (exchange of genetic material b/w bacteria)

homeostasis

maintaining a stable internal environment within a certain range despite external fluctuations

growth

to increase in cell size and dry mass

development

process of change in an organism’s form, func., and complexity → specialization + maturation

movement

ability to change position or orientation

sessile

organisms that cannot move on it’s own - permanently attached to a substrate (e.x. seabed, soil)

motile

organisms capable of free, voluntary movement of location

response to stimuli

organisms can detect and respond to environmental changes

chemotaxis

organisms that react to chemical signals

phototaxis

organisms that react to light