Introduction
Good morning learners. Our topic for today`s lesson is Photosynthesis.
Please watch the video below so that you can have better understanding of Photosythesis
Task
Due date: 30 August 2021
Marks: 27
Task: 2
Look at the practical performed on the process video and answer the questions that follow:
Question 1
a.) What is the investigative question for this practical? (2) b.) Write an appropriate hypothesis for this practical. (2)
c.) There are several variables involved in this practical. State the following variables: i. Controlled variable (1) ii. Independent variable (1) iii. Dependent variable (1)
d.) What results do you record? (2) e.) State a suitable conclusion to this experiment. (3)
Question 2
(Adapted from Solutions for all Life Sciences, Grade 11, Macmillan Enrichment Activity, p136) Design an investigation
Conrad observed that a water plant in a beaker of water
produced different numbers of bubbles at different times of
the day (see Figure 2.1). The water plant seemed to
produce a lot of bubbles when it was bright and sunny and
fewer bubbles in the early morning and late afternoon when
there was not as much light. Conrad’s teacher told him that
the bubbles produced by the plant were oxygen gas given
off by the plant during photosynthesis. Conrad thought of a
hypothesis based on his observation: ‘An increase in light
intensity causes an increase in the rate of photosynthesis’.
He decided to test his hypothesis in a simple investigation.
The aim of the investigation was: ‘To determine whether an
increase in light intensity causes an increase in the rate of
photosynthesis’.
Fig. 2.1 Conrad’s observation
Conrad worked out a method for his investigation and selected the apparatus that he would need (see Figure 2.2).
a.) Use the information that you have been given in the case study to work out a method that you could use to carry out this investigation. Use only the apparatus that is shown in Figure 2.2. (12)
b.) Identify the independent variable, the dependent variable and at least one controlled variable for this investigation. (7)
c.) Describe any safety precautions that you would take in carrying out the investigation. (2) d.) Design a table to collect the results of the investigation. (3)
Process
Dear learners please watch the video below to help you with the practical given above.
Light phase
1. It takes place in the granum.
2. The sun emits radiant energy( light energy)
3. Radiant energy is absorbed by chlorophyll
4. Chlorophyll converts radiant energy into chemical potential energy
5. Chemical energy is used for photolysis and photophosphorylation
6. Photolysis- splitting water into hydrogen and oxygen
7. Hydrogen is carried by co-enzymes NADP into dark phase
8. Oxygen is released into atmosphere
9. Photophosphorylation: ADP combines with p to form ATP
10. ATP is transported into dark phase
Dark phase
1. It takes place in the stroma
2. Carbo dioxide from atmosphere combines with C5 compound to form C6 compound
3. C6 compound is unstable, as it breaks down into two C3 compounds
4. C3 compound receives energy from NADPH2 and ATP from light phase
5. The C3 compound is energy rich and is called PGAL
6. The C3 compound combines with another C3 compound from another dark phase to form C6 compound ( glucose)
7. The other C3 compound undergoes chemical reaction to form C5 compound.
Evaluation
Marking criteria for photosynthesis practical.
| Questions and marks | ||||||||||||||
Results recorded? 3 |
||||||||||||||
| Method used? 12 |
Conclusion
Dear learners please look at this last video that will help you in preparation for the next class and go through the factors affecting the rate of photosynthesis in your textbook which we will deal with in our next class.
Credits
Teacher Page
During these Covid -19 times our only escape and way of ensuring that you get the quality education that you deserve is through online learning. please feel free to email me at any time you need clarity.
Ms KS Khalo