Identify the parts labelled a, b, and c in Figure 1, and explain their functions and significance in a timber species.

Here are the solutions to the questions based on Figure 1:

50. The part labelled 'a' in Figure 1 is ....................
Part 'a' points to the outermost layer of the wood, which is the cambium.

• V - Cambium The correct option is d. $\boxed{\text{d. V}}$

51. The part labelled 'b' in Figure 1 is ....................
Part 'b' points to the lighter, outer wood, which is the sapwood.

• IV - Sapwood The correct option is c. $\boxed{\text{c. IV}}$

52. The part labelled 'c' in Figure 1 is ....................
Part 'c' points to the darker, inner wood, which is the heartwood.

• III - Heartwood The correct option is c. $\boxed{\text{c. III}}$

53. Which of the parts in Figure 1 can tell the age of a timber species?
The age of a tree is determined by counting its annual growth rings.

• II - Annual growth rings The correct option is b. $\boxed{\text{b. II}}$

54. Which of the parts is majorly responsible for conducting the sap in the timber species?
Sapwood is the living wood that transports water and nutrients (sap) from the roots to the leaves.

• IV - Sapwood The correct option is d. $\boxed{\text{d. IV}}$