SCI1186 Lecture Notes - Lecture 10: Parenchyma, Phloem, Dicotyledon
16 Jun 2018
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Week 10 – Leaf Structure and Function
LEAVES IN ACTION: PHOTOSYNTHESIS
Leaves:
• Overriding function is usually photosynthesis
• Leaf structure is correlated with leaf function
• Dicot leaves:
o Distinct blade-like structure and have part of the branch in the leaf (petiole)
o Net-like vein pattern (e.g. maple tree)
• Monocot leaves:
o Base sheaths around stem and do not have a petiole
o Veins parallel (e.g. corn plant or grass)
• Anatomy
o Internal structure related to function
o Light catching tissues
▪ Parenchyma with chloroplasts
o Transport tissues
▪ Xylem and phloem in veins
• Structure:
o The main function is to aid with photosynthesis
o Directly related to the function
o Contain parenchyma and chloroplasts as they are light
catering tissues
o Also contain xylem and phloem in the veins as they
are key transport tissues
o The cuticle is the outermost layer and covers
the epidermis. It has a waxy texture and is used
to prevent water loss
o The stomata is an opening on the leaf where
water leaves and gas enters
o The middle part of the leaf is called the
mesophyll and is made up of spongy
parenchyma and palisade parenchyma. It is also
a cell that contains many chloroplasts
o The chloroplast is an organelle which contains
an inner cavity surrounded by an outer
membrane
o The inner cavity contains stoma and thylakoid
membranes which are stacked in towers (grana)
PHOTOSYNTHESIS
In photosynthesis, solar energy is converted into chemical energy stored in the bonds of organic molecules
6CO2 + 6H2O + light energy → C6H12O6 + 6O2
It is the process which converts solar energy into chemical energy. This chemical energy is stored in organic bonda,
which are broken when energy is required. In order for photosynthesis to work, the leaves must be able to catch
light, store energy so it can be used later, and it must manage the input and output of gases
The cells and tissues in leaves are then used by the stoma, for the Calvin-Benson Cycle
What do you need to achieve this?
• A way to catch light energy
• A way to store the energy
o To do work
o So that it can be used later
• Ways to manage inputs and outputs
• Leaves, their tissues and cells are structured to make photosynthesis happen
The energy that enters the chloroplasts as sunlight becomes stored as chemical energy in organic compounds
The light reactions capture solar energy
• Converted to chemical energy
Carbon fixation reactions convert CO2 to simple sugars
Document Summary
It is also a cell that contains many chloroplasts: the chloroplast is an organelle which contains an inner cavity surrounded by an outer membrane, the inner cavity contains stoma and thylakoid membranes which are stacked in towers (grana) In photosynthesis, solar energy is converted into chemical energy stored in the bonds of organic molecules. 6co2 + 6h2o + light energy c6h12o6 + 6o2. It is the process which converts solar energy into chemical energy. This chemical energy is stored in organic bonda, which are broken when energy is required. In order for photosynthesis to work, the leaves must be able to catch light, store energy so it can be used later, and it must manage the input and output of gases. The cells and tissues in leaves are then used by the stoma, for the calvin-benson cycle. The energy that enters the chloroplasts as sunlight becomes stored as chemical energy in organic compounds.
