Biology teacher. HELP!?

Question

describe how the internal growth of an organism is brought about.

Answer 1

If by internal growth of tissues you mean to develop an organism:

After fusion of gametes at fertilisation the resultant zygote divides by mitosis to form a ball of genetically identical cells.

these then undergo differentiation to form the final tissues in the organism. Differentiation involves 'switching on ' certain genes and 'switching off' others so that the resultant cells will only produce the necessary proteins for their final role.

Hope this helps!

Answer 2

While this question is extremely vague, internal growth is caused by Mitosis. It is when cells reproduce. It is similar to when amoebas split into two.

Cells will keeping dividing and thats hwo the body internally grows.

As far as the body growing and mainting proper function, when the body first begins to grown (an embryo for example) Special cells called stem cells are the first to preform mitosis. These are essential to the internal growth because the stem cells  can become any cell they want, thus they help form the inital growth of key tissues and organs.

*This is the diferation that Claire refers to :) You can always count on a teacher to give you a definition

After key tissues and organs are developed the cell will preform mitosis when anything is damaged to internally replace what is lost. (At this type Protoonco genes become more active signaling mitosis)

For more in-depth look at Mitosis refer to your book.