Question

Spring wood (early wood) differs with autumn wood (late wood) in
(a)Size of vessels and tracheid
(b)Thickness of cell wall
(c)Amount of wood
(d)All of the above

Answer 1

Hint: The activity of the cambial ring is not uniform throughout the entire year but markedly affected by the variations in the external environment i.e. climate as well as the internal environment of the plant.

Complete answer:
In temperate regions, like Asia, central North America, etc. the climatic conditions are not uniform throughout the year and different seasons show different climates. The secondary xylem of the wood produced is different in different seasons due to the differential activity of cambial.

SPRINGWOOD	AUTUMN WOOD
In the spring season, Cambial is very active and produces a large number of xylary elements i.e. vessels, tracheid, xylem fibers, and xylem parenchyma.	In the winter season, Cambial is less active and as a result, fewer xylary element are formed
The vessels are produced with the wider lumens as more water is needed to meet the requirements by an increased transpiring surface.	The vessels have narrow lumen as less water is needed in the season.
The wood formed during this season is called the springwood or earlywood.	The wood formed in this season is called autumn wood or latewood.
The springwood is lighter in color and has a lower density	Autumn wood is darker in color and has a higher density.
The transition from springwood to autumn wood is gradual (slow)	The transition from autumn wood to springwood is sudden (fast).

The two kinds of wood (spring and autumn wood) that appear as alternate concentric rings of light and dark color constitute an annual ring. Hence, one annual ring includes one circle of spring and one circle of autumn wood.

So, the answer is ‘All of the above’.

Note: The annual ring represents one year, it is also called a growth ring because as the growth keeps on taking place this annual ring keeps on increasing in numbers.
One annual ring is the combination of one ring each of spring and autumn wood seen by the difference in colours. Thus by counting the number of annual rings we can determine the age and number of seasons a tree has lived through.