BOT2601
Assignment 2
Semester 2
Unique No: 158633
DUE 12 September 2025
, Assignment 02
Due date: 12 September 2025 @11pm
Unique number for this assignment: 158633
Question 1 [15]
1.1 Structure and function of the cuticle (5)
The cuticle is a continuous hydrophobic layer that covers the outer walls of epidermal
cells on the aerial parts of plants. It is mainly composed of cutin (a polymer forming the
structural matrix) and waxes, which may occur within the matrix (intracuticular) or on the
surface as crystals or films (epicuticular). In some species, a resistant polymer called
cutan is also present. Structurally, the cuticle can be divided into a cuticle proper and a
cuticular layer. Its thickness and composition vary depending on the plant organ and
environmental conditions.
Functionally, the cuticle plays a crucial role in reducing non-stomatal water loss,
regulating the permeability of gases and solutes, and providing a barrier against
pathogens, pollutants, and mechanical damage. The wax layer also reflects excess
radiation, contributing to UV protection and temperature regulation. In addition, the
cuticle participates in defense signalling and helps maintain the structural integrity of
epidermal cells.
1.2 Non-glandular trichomes (5)
Non-glandular trichomes are hair-like outgrowths from the epidermis that lack secretory
structures. They may be unicellular or multicellular, and can take diverse forms such as
simple, branched, stellate, or scale-like. Their cell walls may be thickened, lignified, or
silicified, and some trichomes die at maturity while others remain alive.
These trichomes perform important protective roles. They reduce water loss by
increasing the boundary layer thickness, reflect excessive sunlight to lower leaf
temperature, and act as a physical barrier against herbivores and insects. Some non-
Assignment 2
Semester 2
Unique No: 158633
DUE 12 September 2025
, Assignment 02
Due date: 12 September 2025 @11pm
Unique number for this assignment: 158633
Question 1 [15]
1.1 Structure and function of the cuticle (5)
The cuticle is a continuous hydrophobic layer that covers the outer walls of epidermal
cells on the aerial parts of plants. It is mainly composed of cutin (a polymer forming the
structural matrix) and waxes, which may occur within the matrix (intracuticular) or on the
surface as crystals or films (epicuticular). In some species, a resistant polymer called
cutan is also present. Structurally, the cuticle can be divided into a cuticle proper and a
cuticular layer. Its thickness and composition vary depending on the plant organ and
environmental conditions.
Functionally, the cuticle plays a crucial role in reducing non-stomatal water loss,
regulating the permeability of gases and solutes, and providing a barrier against
pathogens, pollutants, and mechanical damage. The wax layer also reflects excess
radiation, contributing to UV protection and temperature regulation. In addition, the
cuticle participates in defense signalling and helps maintain the structural integrity of
epidermal cells.
1.2 Non-glandular trichomes (5)
Non-glandular trichomes are hair-like outgrowths from the epidermis that lack secretory
structures. They may be unicellular or multicellular, and can take diverse forms such as
simple, branched, stellate, or scale-like. Their cell walls may be thickened, lignified, or
silicified, and some trichomes die at maturity while others remain alive.
These trichomes perform important protective roles. They reduce water loss by
increasing the boundary layer thickness, reflect excessive sunlight to lower leaf
temperature, and act as a physical barrier against herbivores and insects. Some non-
