Directions: Match the statements below to the theories proposed by Lamarck.
Write the letter of the best answer in your paper.

1. There is a need for an organism to change
to be able to adapt to its environment.

2. A body part is likely to improve and
develop if it is constantly used.

3. Any improvement in an organism
will be passed on to its offspring.

4. A body part becomes vestigial when an
organism use do not use it often.

5. New needs arise in animals as a result
of a change in the environment.

A. Theory of Use and Disuse.
B. Theory of Need.
C. Theory of Acquired traits.
D. Theory of Selection.

-According to Lamarck, new needs arise in animals as a result of a change in the environment. This leads to new types of behaviour involving new uses of pre-existing organs. Their use leads to an increase in size or to other methods of functioning. Conversely, the disuse of other parts leads to their decline. It is the resulting material alterations that are inherited.

The examples that Lamarck gives to illustrate his doctrine are illuminating. In animals, as stated above, a new environment calls forth new needs, and the animal seeks to satisfy them by making some effort. Thus, new needs engender new habits, which modify the parts. The effects are inherited. For example, the giraffe, seeking to browse higher and higher on the leaves of trees on which it feeds, stretches its neck. As a result of this habit, continued for a long time in all the individuals of the species, the giraffe’s front limbs and neck have gradually grown longer.

THEORY OF USE AND DISUSE

- Preformation and natural selection. He enunciated the law of use and disuse, which states that when certain organs become specially developed as a result of some environmental need, then that state of development is hereditary and can be passed on to progeny.

THEORY OF ACQUIRED CHARACTERISTICS

- Lamarck is best known for his Theory of Inheritance of Acquired Characteristics, first presented in 1801 (Darwin's first book dealing with natural selection was published in 1859): If an organism changes during life in order to adapt to its environment, those changes are passed on to its offspring. He said that change is made by what the organisms want or need. For example, Lamarck believed that elephants all used to have short trunks. When there was no food or water that they could reach with their short trunks, they stretched their trunks to reach the water and branches, and their offspring inherited long trunks.