Question

Which of the following growth is related to cell enlargement?
a) Auxetic growth
b) Multiplicative growth
c) Accretionary growth
d) None of the above

Answer 1

Hint: Growth is an increase in size or mass or volume by an internally regulated process. Cell enlargement is related to an increase in the volume of the organisms.

Complete answer: Growth is the self-multiplication of living substances. This was explained by J.X.Huxley.
>Cellular growth takes place by any of the three growth processes.
>Cell proliferation: This is cell multiplication due to cell division.
>Cell enlargement: In this, the cell does not divide. There is an increase in the size of the cell. This is due to the secretion of more cytoplasm.
>Cell growth by accretion: The cell growth is by secretion of substances from the outside.

Based on the above processes, cell growth (in animals) are of three types.
1) Multiplicative Growth: Due to rapid cell proliferation or cell division, the number of cells increases and this causes Multiplicative Growth. This is due to Mitosis. It is seen in embryos.
                                                 

2) Auxetic Growth: In this, the cell increases in size and not in number. Thus cell enlargement is seen. It is also known as hypertrophy. It is seen in Nematodes, Tunicates, etc. (This is also seen in plants. Auxins are plant hormones responsible for Auxetic growth).
                                                 

3) Accretionary Growth: In adults, some cells lose their ability to divide. Thus secretions or extra-cellular matrix that is needed for cell growth. This is seen in bone and cartilage.
                                        

Here the question is about growth seen in Cell enlargement. So from the above explanation we can say that “Auxetic growth” is related to cell enlargement.

Hence option ‘a’ is the correct answer.

Note:Animals show additional growth too. This is Appositional Growth. In this growth new layers are formed on existing layers. This is seen in bones as addition of lamellae takes place.