B6 Flashcards
What is the plant cell comprised of
Cell wall, chloroplasts, cell membrane, mitochondria, large vacuole, cytoplasm, nucleus, mitochondria, ribosome
What is the definition of photosynthesis
Photosynthesis is a series of chemical reactions by which plants transform light energy into chemical energy, manufacturing carbohydrates from raw materials.
Chloroplast function
transforms light energy into chemical energy in molecules for the synthesis of carbohydrates.
what are chloroplasts comprised of
-Thylakoids: facilitates light reactions
-Stroma: fluid-filled place where the calvin cycle takes place.
what is the chemical equation for photosynthesis
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
word equation for photoynthesis
Carbon dioxide + Water + Light energy → Glucose + Oxygen
what are the raw materials, products and byproducts of photosynthesis?
raw materials: carbon dioxide and water
byproduct: oxygen
Product: glucose
What form does glucose take in order to be transformed throughout the plan
sucrose (disaccharide)
list structures found within a leaf
waxy cuticle
Upper epidermal cells
Palisade cells
Spongy Mesophyll layer
Vascular Bundle
Lower Epidermis
Stomata
Guard cells
Describe and state the function of the waxy cuticle
Structure: A waxy, transparent layer on the surface of the leaf.
Function: Reduces water loss from evaporating and provides protection.
Describe and state the function of the upper epidermal cells
Structure: A single layer of cells just below the cuticle.
Function: Protects the leaf and allows light to pass through to the layers below.
Describe and state the function of Palisade cells
Structure: Tightly packed, column-shaped cells containing many chloroplasts.
Function: Main site of photosynthesis, as it captures the most light.
Describe and state the function of the spongy mesophyll layer
Structure: Loosely packed cells with air spaces between them, containing fewer chloroplasts.
Function: Facilitates gas exchange (CO₂ and O₂)
Describe and state the function of the vascular bundle
Structure: Includes xylem and phloem tissues.
Xylem: Transports water and minerals from the roots to the leaves.
Phloem: Transports sucrose and other nutrients from the leaves to other parts of the plant.
Describe and state the function of the lower epidermis
Structure: A single layer of cells on the underside of the leaf.
Function: Protects the leaf and contains stomata for gas exchange.
Describe and state the function of the stomata
Structure: Pores in the lower epidermis (and sometimes the upper epidermis).
Function: Regulate gas exchange (CO₂ enters, O₂ and water vapor exit).
Describe and state the function of guard cells
Structure: Specialized cells surrounding each stoma.
Function: Control the opening and closing of the stomata to regulate water loss and gas exchange.
What two ways is the glucose made during photosynthesis used?
- as an energy source
- for storage
- for structural support
- to assist pollination
in what form is glucose stored by plants
starch
How is glucose used as an energy source (+ for growth)
Some of the glucose produced by photosynthesis is broken down during respiration to release energy.
How is glucose used for storage
-Plants often convert glucose to starch. This is stored in granules in the chloroplasts and cytoplasm and acts as an energy store.
Where is starch usually stored in plants
Roots
Tubers
Seeds
Fruits
Stems
Leaves (to a lesser extent)
How is glucose used for structural support
converted to cellulose which is an important component of the plant cell walls
How does glucose assist pollination
It is used to make nectar- a sweet, sugary liquid that attracts insects and birds.
What are minerals
a solid inorganic substance of natural occurrence.
What do minerals form
ions which are then absorbed by the root hair cells of plants
What is the function for nitrate ions and what happens when the plant is deficient
Function: synthesis of amino acids
If deficient: stunted growth & yellow leaves
What is the function for magnesium ions and what happens when plants are deficient
Function: Chlorophyll production
If deficient: Stunted growth & yellow leaves
What does chlorophyll have
high concentrations of magnesium
what are the factors affecting the rate of photosynthesis
- Light energy
- Concentration of CO2
- Temperature
What happens to the rate of reaction in relation to light intensity (what does this look like on graph)
The higher the light intensity, the higher the rate of photosynthesis
Upward slope until reaches a plateau- at a certain point, it won’t matter how much more light you give. The rate will be at its max or one of the other factors is in short supply.
What happens to the rate of reaction in relation to concentration of CO2 (what does this look like on graph)
The higher the CO2 level, the faster the rate of photosynthesis provided there is plenty of light & a suitable temperature
Upward slope until reaches a plateau
What happens to the rate of reaction in relation to temperature (what does this look like on graph)
As temperature increases, the rate of reaction also increases. Because higher temperatures mean more frequent collisons.
the graph typically has a sharp rise initially, followed by a decrease after reaching the optimal temperature.
Why does the rate of photosynthesis graph in relation to temperature look like that
After a certain temperature (optimum temperature), the rate of reaction will start to decrease due to denaturation of enzymes (if enzymes are involved), causing the reaction to slow down or stop.
How do you test for starch in a leaf?
- Place a leaf in the beaker of boiling water for 30 seconds.
- Remove the leaf.
- Place the leaf in a test tube of alcohol solution until all of the green colour has been removed from the leaf.
- Remove the leaf from test tube and dip it into hot water to soften it and to remove excess alcohol.
- Place the leaf on a white tile and cover it with iodine solution. Observe any colour changes.
What apparatus needed for testing for starch
a ‘destarched’ leaf
forceps
beaker of boiling water
timer
test tube of alcohol solution
white tile
iodine solution
Bunsen burner or spirit burner.
How to best destarch a leaf
leave in a dark room for 24 hrs
What will happen to the leaf when starch is present
The leaf will turn blue-black
what is a variegated?
a leaf that has two different colours (green and non green)
Equipment needed to investigate the need for chlorophyll in photosynthesis
a plant with variegated leaves
forceps
beaker of boiling water
white tile
iodine solution.
Method for investigating the need for chlorophyll
Destarch a plant with variegated leaves for 24 hours.
Move the plant and place it in a warm, sunny area for 48 hours.
Test one of the leaves using the method for the starch test
How do you know after the practical that chlorophyll was needed for photosynthesis
You should see that the areas of the leaf that were green become blue-black when iodine is added.
The parts of the variegated leaf without chlorophyll do not produce starch. This shows that chlorophyll is essential for photosynthesis.
What is used to test whether CO2 is needed for photosynthesis?
Potassium hydroxide (KOH) which absorbs carbon dioxide.
equipment to test for the need for CO2 for photosynthesis
a plant with green leaves
conical flasks with bungs
dilute potassium hydroxide solution
forceps
beaker of boiling water
white tile
iodine solution.
Method for testing the need for photosynthesis CO2 in photosynthesis
Destarch a plant with green leaves by placing it in a dark room or in a cupboard for 24 hours.
Take a conical flask and insert approximately 50 cm3 potassium hydroxide (KOH) solution.
Insert one leaf from the destarched plant into the flask
Place the plant in a sunny place for 48 hours.
Test the leaves from the conical flask, and those left uncovered, by carrying out the starch test
What would the results for testing the necessity of CO2 be
You should see that the leaf from the flask containing potassium hydroxide does not change colour on addition of iodine, whereas the leaves left exposed to the air are blue-black.
at low light intensities, overall plants will release ________ through ________
at high light intensities, overall plants will release _______ through ________
- carbon dioxide, aerobic respiration
- oxygen, photosynthsis
What is used to estimate the carbon dioxide concentration in the water?
Hydrogencarbonate indicator
what colour will hydrogen carbonate indicator be for different concentrations of CO2?
low- magenta/purple
normal atmospheric- red
high- orange/yellow
when will carbon dioxide concentration be low
When intensity of light is high
this is because photosynthesis occurs and thus carbon dioxide is absorbed.
When intensity of light is low, respiration exceeds photosynthesis. Thus carbon dioxide concentration would be high.
What is an adaptation of the cuticle in the leaf
waxy layer
What is an adaptation of chloroplasts in the leaf
Contains chlorophyll to absorb light, enzymes and structures needed for photosynthesis
What is an adaptation of the upper epidermis in the leaf
thin layer without chloroplasts, which lets light pass through for photosynthesis
What is an adaptation of the palisade mesophyll layer in the leaf
box-shaped cells that pack closely together; each cell has lots of chloroplasts pushed to the edges of the cell by a large vacuole so they can absorb more light
What is an adaptation of the xylem and phloem in the leaf
xylem: made from dead cells, forming hollow, waterproof tubes, through which water passes
phloem:consists of sieve tubes (through which the sucrose is transported) and companion cells (that provide energy for the transport)
What is an adaptation of the lower epidermis in the leaf
thin layer that (apart from guard cells) does not contain chloroplasts, which lets light pass through for photosynthesis
What is an adaptation of guard cells in the leaf
entry and loss of water from the guard cells (due to osmosis) results in changes in their shape; this in turn leads to the opening and closing of the stoma
What is an adaptation of the stomata in the leaf
the size of the opening changes in response to the internal and external environments of the plant
What is an adaptation of the spongy mesophyll in the leaf
cells are loosely spaced, creating air spaces to allow diffusion of gases throughout the leaf
What types of minerals are there? Function? Deficiency?
-nitrate ions
synthesis of amino acids
deficiency: stunted growth and yellow leaves
-Magnesium ions
Chlorophyll production
stunted growth and yellow leaves
