Photosynthesis test

1. What is the correct word equation for photosynthesis?

  Carbon Dioxide + Water → Glucose + Oxygen

2. What is the chemical equation for photosynthesis?
  B. H₂O + CO₂ + Light Energy → C₆H₁₂O₆ + O₂

 

3. Why is photosynthesis important for the balance of gases in the atmosphere?
  It produces oxygen and removes carbon dioxide.

4. Which part of the leaf contains most of the chloroplasts and carries out the most photosynthesis?
Palisade mesophyll

5. What is the function of stomata in a leaf?
  Allow gas exchange

6. The veins in a leaf contain:
. Xylem and phloem

7. What do guard cells do?
Open and close stomata

Short Answer / Essay Questions

1. Write the word and chemical equations for photosynthesis.
(Word equation + Balanced chemical equation)

Carbon dioxide + Water + light  produces Glucose and Oxygen 

CO2 + H2O → C6H1206 + O2

2. Explain how photosynthesis helps maintain the balance of carbon dioxide and oxygen in the atmosphere.

They maintain the balance in the environment by plants taking in excess carbon dioxide in the atmosphere during photosynthesis, which then produces and releases oxygen. This helps maintain the amount of gases in the atmosphere, creating a safe environment for animals and humans. 

3. Describe how light energy is converted into chemical energy during photosynthesis.

Light energy is absorbed by the chlorophyll, which is then converted into chemical energy.This chemical energy then is used to produce glucose from carbondioxide and water. 

4. Choose three of the following leaf structures and describe both their position and their function:

• Cuticle- On the very top of the leaf, and keeps the leaf moist(water escape) and is waxy
  
  

• Epidermis - Protective outer layers on the bottom and top
  
  

• Palisade mesophyll- Is where most of the light absorption happens because it’s highly packed with chlorophyll (main site for photosynthesis) 

• Spongy mesophyll- Gas exchange
  
  

• Air spaces- allow CO2 and O2 to move easily inside the leaf
  
  

• Stomata help to facilitate gas exchange by letting in carbon dioxide and letting out oxygen
  
  

• Guard cells- Open and close the stomata
  
  

• Veins- Are the Xylem and Phloem, which help to transport
  
  

• Xylem- Helps transport water from the roots to the leaves
  
  

• Phloem- Helps to transport glucose from the leaf to the roots
  
  

5. Imagine you are doing an experiment where a plant is placed in a sealed container with a light on for 24 hours.
a) What changes in oxygen and carbon dioxide levels would you expect?

The oxygen levels would increase as the carbon dioxide levels decreased. This would happen because the plant would photosynthesize for 24 hours, as there would be light the whole time, so the plant would continuously photosynthesize. Taking in the carbon dioxide and releasing the oxygen 

b) What would happen if the light were turned off for 24 hours instead?

As there is no light, there would be no photosynthesis, but there would be respiration occurring. SO, oxygen would decrease, and the carbon dioxide would increase.  

(respiration Increases CO2 levels        C6H12O6 + 6O2 → 6CO2 + 6H2O )

c) What does this tell you about the role of light in gas exchange during photosynthesis?

This shows how light is a crucial part of photosynthesis, which removes carbon dioxide and produces oxygen. 

6. How does the structure and arrangement of cells in a leaf help the plant perform photosynthesis efficiently?
   
   

Leaves have a large surface area, including the flat, thin shape and the arrangement of palisade and spongy mesophyll cells, to capture maximum sunlight.

Experiment 1: Photosynthesis in Elodea (Pondweed)
This experiment investigates how different factors affect the rate of photosynthesis in pondweed by counting the number of oxygen bubbles produced. The setup involves a pondweed sample in water, with a light source placed at a fixed distance. The number of bubbles produced per minute is recorded as an indirect measure of the photosynthesis rate.

• Variables: Light intensity (distance), temperature, carbon dioxide concentration, etc.

• Assumption: The number of bubbles is proportional to the rate of photosynthesis.

🔬 Experiment 2: Light Distance and Photosynthesis Rate
In this experiment, the student investigates how the distance between a light source and the pondweed affects the number of gas bubbles produced per minute. A graph is plotted showing that as distance increases, the number of bubbles decreases, showing that light intensity affects photosynthesis.

• Conclusion: Less light = lower photosynthesis rate = fewer bubbles.

🔬 Experiment 3: Testing Photosynthesis Under Different Light Conditions
This experiment uses test tubes with pondweed and an indicator solution to test the effects of different light intensities on photosynthesis. Bright and dim light conditions are compared. A control tube is used (without pondweed). A water bath helps keep temperature constant.

• Observations: Color changes in the solution indicate CO₂ levels — purple (less CO₂, more photosynthesis), yellow (more CO₂, less photosynthesis).

🔬 Experiment 4: Measuring Gas Production in Photosynthesis
This setup involves pondweed in water inside a beaker, with a gas collection tube to measure the volume of oxygen produced. The goal is to quantify the rate of photosynthesis by directly measuring the gas output.

• Measured variable: Volume or number of bubbles (oxygen) produced over time.