bio study notes
CUTICLE
In addition to its function as a permeability barrier for water and other molecules (prevent water loss), the micro and nano-structure of the cuticle confer specialised surface properties that prevent contamination of plant tissues with external water, dirt and microorganisms.
PHLOEM
Phloem is the vascular tissue responsible for the transport of sugars from source tissues (ex. photosynthetic leaf cells) to sink tissues (ex. non-photosynthetic root cells or developing flowers). Other molecules such as proteins and mRNAs are also transported throughout the plant via phloem.
SPONGY MESOPHYLL
Since the mesophyll cells contain chloroplasts the tissue is also referred to as chlorenchyma . The palisade cells are responsible for photosynthesis because they contain chloroplasts. The spongy mesophyll, together with the intercellular air spaces, allow for the interchange of gases
GUARD CELL
Stomatal pores in plants regulate the amount of water and solutes within them by opening and closing their guard cells using osmotic pressure. In order for plants to produce energy and maintain cellular function, their cells undergo the highly intricate process of photosynthesis. Critical in this process is the stoma
UPPER EPIDERMIS
The Cuticle and Upper Epidermis. Just like our skin helps protect us, leaves have an outer layer that protects them. This outermost layer is called the cuticle. It is generally waxy to protect the leaf and prevent water loss.
LOWER EPIDERMIS
The central mesophyll is sandwiched between an upper and lower epidermis. The mesophyll has two layers: an upper palisade layer and a lower spongy layer. Stomata on the leaf underside allow gas exchange. A waxy cuticle covers all aerial surfaces of land plants to minimize water loss.
PALISADE MESOPHYLL
The spongy mesophyll, together with the intercellular air spaces, allow for the interchange of gases.
STOMATA
Their main function is to allow gases such as carbon dioxide, water vapor and oxygen to move rapidly into and out of the leaf.
