photosynthesis and rate of photosynthesis Flashcards
canadian pondweed experiment steps
Put the pondweed in a beaker of sodium hydrocarbonate
Shine a lamp onto it from a set distance (e.g. 10 cm).
Wait for the pondweed to produce oxygen, then start timing.
Count how many oxygen bubbles are produced in 1 minute.
Repeat at different distances (e.g. 20 cm, 30 cm…). each distance should be 10 c
What’s photosynthesis?
Photosynthesis is the process where a plant uses light energy to make glucose. Chloroplasts absorb the light.
What affects the rate of photosynthesis. What are the 3 limiting factors?
LIght
Co2
Temperature
What is a limiting factor?
A limiting factor is something that slows down a reaction because it’s not available in enough quantity
How does light affect the rate of photosynthesis. why is it a limiting factor
Plants use light energy to power photosynthesis.
If there isn’t enough light, they can’t make glucose fast.
How does light affect the rate of Carbon Dioxide (CO₂) Concentration affect. Why is it a limiting factor?
as kight decrease the rate of CO2 produced decreases
How does temperature affect the rate of Carbon Dioxide (CO₂) Concentration affect. Why is it a limiting factor?
Photosynthesis uses enzymes to carry out the reaction.
If it’s too cold → enzymes are too slow
If it’s too hot → enzymes denature (stop working)
at 45 degress it completely denatures
word equation for photosynthesis
carbon dioxide + water → glucose + oxygen
symbol equation for photosynthesis
6CO2+6H2O→C6H12O6+6O2
📐 What does the Inverse Square Law tell us?
It tells us how light intensity changes with distance from a light source
What is Inverse Square Law
Light Intensity ∝ 1 ÷ distance²
🧪 Inverse Square Law In symbols
1 ÷ d²
d stands for distance
🧪 Inverse Square Law question.
Use the inverse square law to calculate the light intensity when the lamp is 10 cm from the pondweed.
1 ÷ d²
1÷ 0.1²=0.01a.u.
it is measure in m2 so u need to covnert it
what’s independent variable
The thing you change on purpose.
Example (photosynthesis practical):
The distance of the lamp from the plant (affects light intensity)
what’s control variable
The thing you measure — it depends on the independent variable.
Example:
The number of bubbles per minute (rate of photosynthesis)
what’s dependent variable
The things you keep the same to make it a fair test.
Uses of glucose from photosynthesis
The glucose produced in photosynthesis may be:
used for respiration
converted into insoluble starch for storage
used to produce fat or oil for storage
used to produce cellulose, which strengthens the cell wall
used to produce amino acids for protein synthesis.
To produce proteins,
plants also use nitrate ions that are absorbed from the soil.
what’s cellular respiration ?
Cellular respiration is the process by which cells break down glucose to release energy.
What does the synthesis of proteins involve?
The synthesis of proteins involves amino acids, which are formed from glucose and nitrate ions.
Why is energy needed in metabolism?
Energy from respiration is used to power metabolic reactions like building molecules (synthesis) and breaking them down.
What happens to excess proteins in metabolism?
Excess proteins are broken down to form urea, which is excreted from the body.
respiration in yeast equation
Glucose → Ethanol + Carbon Dioxide
C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂
what is the process of yeast called
This is called fermentation.
what type of respiration occurs in yeast?
anaerobic
