Lecture 5: Photosynthesis, Transpiration, Respiration Flashcards
What are the purposes of leaves?
To carry out photosynthesis and transpiration
What is photosynthesis?
Process where glucose is produced from carbon dioxide and water, using energy from light
What is the chemical equation for photosynthesis?
CO2 + H2O -> (Light and chlorophyll) C6H12O6 + O2
Balance the equation for photosynthesis
Write it out
Describe the process of photosynthesis.
- Plant cells contain chloroplast where photosynthesis takes places
- Chloroplasts contain chlorophyll (green pigment) used to absorb light
- CO2 enters the plant from the atmosphere through the stomata
- Roots absorb water from the soil
- Sugars produced by photosynthesis are translocated throughout the plant through the phloem
- Glucose provides energy to run other chemical reactions and produce other carbs (starch and cellulose)
What does chlorophyll do?
Absorb light in the chloroplast
What are the differences between photosynthesis and respiration?
- Photosynthesis
- Produces glucose
- Traps energy
- Consumes H2O and CO2
- Produces O2
- Needs light
- Only happens in cells that have chlorophyll
- Respiration
- Consumes glucose
- Releases energy
- Produces H2O, and CO2
- Consumes O2
- Does not need light
- Happens in all living cells in the mitochondria
What is the chemical equation for respiration?
C6H12O6 + O2 -> CO2 + H2O + ATP
What is transpiration?
Loss of water vapour in a plant mostly from stomata
What is the purpose of transpiration?
Allows water and nutrients from roots/soil to enter the rest of the plant.
Lifts water and dissolves minerals up the plant against the force of gravity.
Presence of stomata allow CO2 to be absorbed for photosynthesis which cools leaves. (Like sweating)
What is transpirational pull?
Force exerted by transpiration from the leaves draws water up from the roots through the plants.
Force of gravity from leaves transpiring, making the roots draw up more water
Fill in the blank: _____ of the water that enters the roots is released in vapour form
98%
What time of day does transpiration happen?
Daytime because stomata are present
How do stomata work?
Stomata open and close through the use of guard cells. Water flows into guard cells and guard cells become turgid and open a stoma.
What affects transpiration?
High temperature = more evaporation and more diffusion = more transpiration
High humidity = less water vapour movement = less transpiration
Light breeze removes water vapour = increased transpiration
Strong wind causes stomata to be absent = no transpiration
Lots of light enlarges stomata opening = more transpiration
What reduces the rate of transpiration?
Drought-tolerant leaves with thick waxy cuticles prevent evaporation.
Spines can store water and reduce water loss.
Sunken stomata are located deeper in the epidermis and trap moist air.
Rolled leaves cover the stomata as less surface area is exposed.
Smaller leaves reduce the rate of transpiration due to a smaller surface area.
What can hydrophytic plants do to increase their oxygen supply?
Air spaces in tissue to make the plant buoyant. That way leaves can float on the water surface to absorb light and create O2.
Stomata on the upper leaf surface absorb CO2 then H2O in water allows photosynthesis to occur. Therefore, respiration (a method to create ATP) can happen!
Why do hydrophytic plants receive less oxygen?
Oxygen has low solubility in water which makes it hard for hydrophytic plants to absorb it.
What is the glucose produced in photosynthesis used for?
Provides energy to run other chemical reactions (ie. respiration) and helps produces other carbs like starch and cellulose
