What were lamarcks ideas about evolution and why were those ideas incorrect

Lamarck thought organisms changed during their lifetimes based on their needs and that those changes were then passed on to the next generation. This is incorrect because organisms cannot acquire traits during their lifetimes, like longer arms or a longer neck, and pass them on to their offspring.

Lamark suggested that organisms can acquire traits which benefit them without any genetic means. He suggested that a change was gradually introduced into organisms of a species during their lifetime and this change could then be seen in the offsprings.

This idea was wrong because an organisms characteristics cannot change in his lifetime.

The theory of Lamarck's inheritance can be disregarded by our knowledge about hereditary genetics.