Question

The girth of stem increases due to the activity of
A. Lateral meristem
B. Apical meristem
C. Intercalary meristem
D. Apical and intercalary meristem

Answer 1

Hint: Every plant grows in life. This growth is possible due to the division of cells in the various regions of the plant. Some of the cells differentiate to become a specialized cell while some just help in the growth of the plant.

Complete answer:
Meristematic cells in the plants are responsible for the increase in the size of the plant both horizontally and vertically. There is primary and secondary growth.
Apical meristem does lateral growth and includes primary growth. Secondary growth increases the plant horizontally.

Let us learn about the options given.
> Option A: Lateral meristem: this grows the plants laterally that is horizontal. So the plants grow via the girth. Thus making it thicker.

> Option B: Apical meristem: it grows the cells at the apex (tip) of the plant. So the plant grows longitudinally. The cells divide and make the plant grow.

> Option C: Intercalary meristem: This is also like the apical meristem but grows the plant longitudinally in the middle part of the plant.

> Option D: Apical and intercalary meristem: the apical and intercalary are the primary meristems which increase the length of the plant at the tip and in the middle section respectively.

Hence, the correct answer is option (A).

Note: Lateral meristem is the part of the secondary growth. This occurs in the woody vascular plants. It grows the plant in diameter. The examples are the vascular cambium and cork cambium. This produces from the ring of vascular cambium in roots and stems.