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Answer 1

Lamarckism:- Lamarckism was proposed by Jean-Baptiste de Monet Lamarck in the year 1744-1829. This theory was based on the principle that all the physical changes occurring in an individual during its lifetime are inherited by its offspring. For eg., the development of an organ when used many times. This theory has been explained here.

Darwin's theory of natural selection:-

1. More individuals are produced each generation that can survive.

2. Phenotypic variation exists among individuals and the variation is heritable.

3. Those individuals with heritable traits better suited to the environment will survive.

4. When reproductive isolation occurs new species will form.

Embryology:- Embryology is the study of development of an embryo from the stage of ovum fertilization through to the fetal stage.

The ball of dividing cells that results after fertilization is termed an “embryo” for eight weeks and from nine weeks after fertilization, the term used is “fetus.”

Evolution:- The process by which modern organisms have descended from their ancestors, with changes in their allele frequencies, is called evolution.

Connecting Link:- A connecting link between two systematic classes of species is an intermediate or transitional state. The other name of connecting links is missing links. It bears characters common to both these groups on either side of its position. Thus it represents an evolutionary line.

Example: Seymouria and Ichthyostagia.

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