Chapter 6 - Plant Nutrition Flashcards
Define Photosynthesis
the process by which plants synthesise carbohydrates from raw materials using energy from light
Mention 3 ways in which organisms can get energy
- living things need biological molecules to make energy
- animals get biological molecules through organic substances they eat
- plants can make some biological molecules from inorganic substances
What is the equation for photosynthesis?
6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
carbondioxide + water → glucose + oxygen
Which substance is crucial for photosynthesis?
chlorophyll
Can substances react without energy?
no
what kind of energy does glucose contain?
energy from the sun
What is oxygen used for after photosynthesis?
released into the atmosphere / water
What is glucose used for after photosynthesis (8)
- provide energy for active transport
- provide energy for growth
- stored as proteins to use later
- chained together to make sucrose to transport glucose around the leaf
- make cellulose
- make nectar
- create amino acids
- to create other substances if the plant doesn’t have enough or them
Where does photosynthesis happen?
leaf, chloroplasts
What is inside the leaf stalk?
vascular bundles arranged in parallel tubes which carry substances to and from the leaf
Why is chlorophyll spread throughout the leaf?
to absorb as much sunlight as possible
How does having a large surface area affect the leaf?
allow for more carbon dioxide to be absorbed into the leaf and allows more sunlight to enter the leaf
Which plant is going to photosynthesise faster; one that is thick or one that is thin?
one that is thin
How is water brought to the leaf?
in tubes called xylem vessels
What is each stomata surrounded with?
guard cells
Define stomata
openings in the surface of the leaf, most commonly lower surface. surrounded by pairs of guard cells, which controls wether stomata opens or closes
Define guard cells
pair of cells that surround stomata and control its openings. They are the only cells in epidermis that contain chloroplasts
What does the stomata do?
allows the diffusion of CO₂ , O₂ and water vapor in and out of the leaf
How does sunlight enter the leaf?
By passing through the transparent cuticle and upper epidermis
How does water reach the chloroplasts?
It travels from the roots into the xylem vessels. Water gets to the chloroplasts by Osmosis
What 4 factors affect photosynthesis?
- supply of raw materials (CO₂ & H₂O)
- quantity and quality of sunlight
- temperature (affects enzyme activity)
- quantity of chlorophyll in leaf
Define Destarching
leaving a plant in the dark long enough for it to use up its starch storage
Describe a general method for seeing where starch normally is on a leaf
- put a plant in the darkness for 4 days
- cover the leaf with a black card that has a shape in it
- leave the plant in the light for 4 days
- use ethanol to remove chlorophyll from the leaves
- use Iodine to see where starch is
Why do only some parts of the leaf contain starch?
because there is only glucose in some parts of the leave and that is what starch is made up of
What is the key for Hydrogencarbonate indicator?
purple: no CO₂
red: little CO₂ (normal air)
yellow: lots of CO₂
Define limiting factor
a factor that is in short supply, which stops an activity happening at a faster rate
What are the limiting factors of photosynthesis?
- light intensity
- temperature
- stomata
What is the relationship between photosynthesis and light intensity?
as the light intensity increases, the rate of photosynthesis also increases up to the point where the plant is photosynthesising as fast as it can
do all plants photosynthesise?
NO
What is the relationship between photosynthesis and temperature?
a plant can photosynthesise faster on a warm day (optimum temperature)
How does the stomata affect photosynthesis?
- CO₂ diffuses into the leaf through stomata
- if stomata are closed, leaf is lacking raw materials
- on REALLY hot days, photosynthesis will slow down
