Overview of Photosynthesis Flashcards
Why is photosynthesis so important to us as humans?
They produce the oxygen we breathe by releasing it from the water molecules
Photoautotrophic organisms carry out photosynthesis
Light energy is absorbed by chlorophyll and converted into chemical energy
Biological molecules stored in plants and algae may be consumed by hetertrophs
What does life depend on?
Continous transfers of energy
What does this energy that eneters the organism depend on?
The type of nutrition
In plants, energy in light is absorbed by chlorophyll and then transferred into chemical energy of the molecules formed during photosynthesis. These molecules are used by the plant to produce ATP during respiration
Non-photosynthetic organisms feed on the molecules produced by plants and then use them to make ATP during respiration
Where is the site of photosynthesis?
Leaf is the main photosynthetic structure in the eukaryotic plants
Chloroplasts are the cellular organelles within the leaf where photosynthesis takes place
Why are leaves adapted to bring and remove waste products?
- Leave bring: (Raw materials of photosynthesis
- Water
- Carbon dioxide
- Light
- Leaves remove its products
- Oxygen
- Glucose
Why is it important that leaves have a large surface area?
- Absorbs as much sunlight as possible
Why is it important with the arrangement of leaves on a plant?
- Minimises overlapping and avoids the shadowing of one leaf by another
Why is it important that leaves are thin?
- As most light is absorbed in the first few micrometres of the leaf
- Keeps the diffusion distance for gases short
Why is it important a leaf has a transparent cuticle and an epidermis?
Let the light through to the photosynthetic mesophyll cells beneath
Why is it important that leaf has long, narrow upper mesophyll cells packed with chloroplasts?
They can collect sunlight
Why is it important that the leaves have numerous amount of stomata for gas exchange?
- So that all mesophyll cells are only a short diffusion pathway from one
What do stomata open and close to?
In response to changes of light intensity
Why do leaves have many air spaces in the lower mesophyll layer?
Allow rapid diffusion in the gas phase of carbon dioxide and oxygen
Why do leaves have a network of xylem and phloem?
Brings water to the leaf cells - xylem
carries away the sugars produced during photosynthesis - phloem
What is the chemical equation of photosynthesis?
6CO2 + 6H2O -> (light) C6H12O6 + 6O2
What is the word equation for photosynthesis?
carbon dioxide + water -> glucose + oxygen
What is the problem with the chemical/word equation for photosynthesis?
It is oversimplified
photosynthesis is a complex metabolic pathway involving many immediate reactions
it is a process of energy transferral in which some of the energy in light is conserved in the form of chemical bonds.
Three main stages of photosynthesis simplified
Stage 1 - capturing of light energy
Capturing of light energy by chloroplasts pigments such as chlorophyll
The three main stages of photosynthesis simplified
Stage 2 - the light-dependent reaction
the light-dependent reaction in which some of the light energy is absorbed is converted into chemical bonds.
During this process, electron flow is created by the effect of light on the chlorophyll, causing water to spilt (photolysis) into protons and electrons, and oxygen.
The products are reduced NADP, ATP and oxygen
The three main stages of photosynthesis simplified
Stage 3 - the light-independent reaction
the light-independent reaction in which these protons (hydrogen ions) are used to produce sugars and other organic molecules
Where does photosynthesis occur in eukaryotic plant cells organelles?
Chloroplasts
What typically size is chloroplasts?
2 - 10 µm
However sometimes vary in shape and size
(usually disc shaped)
Do chloroplasts have a double membrane?
Yes
Structure of grana
There are stacks of 100 disc-like structures called thylakoids
this is where the light-dependent reaction of photosynthesis takes place.
Within the thylakoids is a photosynthetic pigment called chlorophyll
Some thylakoids have tubualr extensions that join up with thylkaloids in thr adjacent grana. These are called intergranular lamellae
Structure of stroma
- It is a fluid-filled matrix where the light-independent stage of photosynthesis takes place
- Within the stroma are a number of other structures such as starch grains
Diagram of chloroplast
What is granum?
A stack of thylakoid discs
What is plural of granum?
Grana (more than one stack)
How does water move through plant?
They use the xylem - cohesion tension theory
Adhesion - attracted to the interior of the capillary
Cohesion - between the water molecules
Tension - pull through the transpiration stream
Where do algae and plants carry most of their photosynthesis from?
In the ocean
What is the chloroplast membrane?
Double membrane permeable to glucose, oxygen , carbon dioxide and someions
Why is lipid droplet in a chloroplast?
Energy store made from sugars produced by photosynthesis
Why are plants green?
- packed full of chlorophyll pigment
- absorb all the colours but reflect green
- best colour for plant is black as it would absorb all light
What does hydrogen transfer mean?
Electrons are transferred
What is the process of adding phosphate to ATP
Phosphorylation
