The characterisitcs of life

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Metabolism is the sun of all the chemical reactions in an organism e.g. respiration, digestion

(controlled by enzymes)

Spontaneous generation was a theory proposed by Aristotle that living things can arise from non-living matter, e.g. maggots on rotten meat and frogs in dried mud. This was disproved as maggots develp from eggs laid by flies in meat (the maggots themselves developing into flies) and frogs emerge from mud because they hibernate there.

The continuity of life means that living things arise from other living things of the same type. This is called biogenisis.

Life is defined as the possession of all of the characterisitics of life

The characteristics of life :

Sensitivity/Response

Nutrition

Organisation

Reproduction

Excretion

SNORE

Organisation

Living things are composed of:

Cells

Tissues

Organs

Organ systems

Some organisms such as bacteria and Ameoba are unicellular (single-celled)

Nutrition

The way in which organisms obtain and use their food

Autotrophic e.g. plants

Heterotrophic e.g. humans

Excretion

The removal of the waste products of metabolism from the body.

Plants have less need for excretion because they are autotrophic and do not take in or produce as much waste. Plants excrete waste gases through stomata on the underside of their leaves.

Sensitivity/Response

The way in which living organisms react to changes called stimuli in their environment.

Most animals move obviously from place to place (locomotion). Plants move more slowly.

Reproduction

The production of new individuals to prevent the exctinction of the species.

Asexual - simple organisms split into two or more identical offspring.

Sexual - union of two sex cells formed by two parents. The offspring carries genetic information from both parents.

The characterisitcs of life