Video: Review photosynthesis

﻿Hi, everyone. Welcome back to unit four of bio-energetics. I'm Miss Strmec, in this lesson we will be reviewing all of the key concepts from the first half of this unit about photosynthesis. During this lesson, you will need a pen and a piece of paper. Feel free to pause your video here and collect the equipment if you don't have it already. Now, make sure that you're in a distraction-free environment and that your phone is on silent. When you're ready, let's begin the lesson. Today's lesson is going to be split into four revision categories. First, we're going to review the photosynthesis equations. Next, we're going to look at the uses of glucose. Third, we're going to look at the variables that we used for the required practical. And finally, we're going to review the limiting factors of photosynthesis. Let's begin by looking at the photosynthesis equation. First, we're going to look at the word equation. You should recall that water and carbon dioxide are the reactants. And these are the two molecules that go into the photosynthesis reaction. Glucose and oxygen are the products and these are what get released from the photosynthesis equation to be used either by the plant, or released by the plant for other organisms to use, next let's have a look at the symbol equation. So when we do the symbols we're looking for the chemical symbols of each of the words, starting with water, which you should remember as H2O. CO2 is carbon dioxide, remember that these are the reactants. In the products we have glucose, glucose's symbol is C6H12O6 and finally we have O2 which is oxygen. You should remember that like most chemical equations photosynthesis needs to be balanced. This means that we need to make sure that the number of atoms in the reactants are equal to the number of atoms in the products. This is the law of conservation of mass. Let's have a look now at the balanced photosynthesis equation, so you'll see that I first popped up the symbol equation as it is. At this moment the atoms in the reactants are not equal to the number of atoms in the products. And in order to increase that number and to make them balanced, we need to place a six in front of the H2O so we need to include six molecules of water. We also need to include six molecules of carbon dioxide. So I place a six in front of carbon dioxide to say that I'm going to be using six molecules. On the product side, we are only creating one glucose. You'll notice that glucose is a much larger molecule and that it requires six carbons and those six carbons come from the six molecules of carbon dioxide that are on the reactant side. Finally, you're going to end up with more oxygen than just one molecule, so in order to balance out the number of atoms of oxygen, we placed a six in front of the O2. Let's do a few quick recall questions. Take a moment to read the question on screen, shout out the answer, I'll give you five seconds. Three, two, one. If you identify the reactions as water and carbon dioxide, excellent job. Next question. Three, two, one, the missing parts of this equation are carbon dioxide and oxygen. Well done. Next question. Three, two, one. If you said glucose, you're correct. Excellent job. Now, we're going to complete some independent practise, so I'd like you to pause your screen here and fill in the missing blanks that are on screen. When you finished, hit resume. Excellent work. The answers to the fill in the blanks are now screen. Pause your video here, mark and feedback your own answers and resume when you're ready. Good work. The next part of this lesson, we're going to be looking at the uses of glucose. I'd like you to take a moment to read and recall the five uses of glucose that are on screen. Let's first discuss respiration. Remember that glucose is used in the respiration equation to release energy. Second, making cell walls. Remember that glucose is converted into cellulose to help to make cell walls. Thirdly, making proteins glucose combines with nitrates from the soil to form amino acids. Amino acids are the building blocks of a protein and proteins can lead to plant growth. Fourth glucose can be stored as lipids, or if you remember the scientific word for fats and stored in seeds. Finally glucose can be stored as starch in the leaves, the roots and the stem, this is a longterm energy storage. Okay, let's now do a few quick recall questions. Read the question on screen and in five seconds I'll tell you the answer. Three, two, one. If you said C cellulose, you're correct, well done. Next question, three, two, one. If you said A, nitrates, you're correct, well done. Next question. Three, two, one. If you answered B seeds, you're correct, well done. Next question, three, two, one. If you said D starch, you're correct, excellent work. Now I'd like you to pause the screen and have a go at the exam-style question below. Be sure to look out for how many marks this question is worth and make sure that your answer has at least four key components. Great work. Take a look at my model answer, be sure to look out for exactly where each mark is coming from. Read, mark and feedback your own answer. Pause the video here and resume when you've finished. Now, we're going to review the variables, from the photosynthesis required practical. Take a moment to read and review, the three variables on screen. Now let's recap those three variables from the required practical. Remember that the hypothesis for the photosynthesis practical was that as light intensity increases, the rate of photosynthesis increases. Try to recall now the independent variable that we used. If you said light intensity, you are correct. You should recall that we moved the pond weed away the lamp at 10 centimetre intervals, in order to alter or decrease the light intensity. Try to recall the dependent variable that we used for the required practical. Remember, you can look at the second half of the hypothesis in order to work out what we measure. If you said the rate of photosynthesis, well done, you should remember that we measured the rate of photosynthesis by counting the number of bubbles produced per minute. And finally have a think and see if you can remember what some of the control variables from the required practical were. There were four that we discussed, species of a plant, colour of the lamp, the temperature and the concentration of carbon dioxide. Now let's do some quick recall questions, to see what you can remember. The question's on screen, answer will be displayed in five seconds. Three, two, one. If you said light intensity, or distance of the lamp to the pond weed, then you're correct. Next question. Three, two, one. If you said the independent variable is found on the X axis, you are correct, well done. Next question. Three, two, one. If you said the Y axis well done, that's correct. Now I'd like you to have a go at some independent practise. Pause your screen here to complete the question below. Take note that it's worth four marks, resume when you're ready. The answers are now on-screen, pause your screen here to mark and feedback your own answers resume when you're ready. Great work on that independent practise. The next section of the lesson that we're going to look at, is the limiting factors of photosynthesis. Take a moment to read and review the four limiting factors on screen. Remember the acronym for what you can recall these factors, T- L- C- C. Now let's have a look at some of the graphs and see if you can work out what the limiting factor is. For the following graph, I'd like you to have a look at where the error was pointing and shout out what you think the limiting factor is. Three, two, one. If you said concentration of carbon dioxide, well done, you're correct. Let's have a look at another one. If you said light intensity, well done. You've got that correct. Remember to look at the X axis to see if the independent variable has changed. That's have a look at another one. Three, two, one. If you said temperature, you're correct. Again, notice how the X axis has changed and the independent variable is now temperature. I'd like you to now complete some independent practise. I've included an exam question on screen, I'm also going to include some tips of what to look out for, when you're identifying what's occurring in the line, A, B and C. When you're looking at line A, remember to look at the independent variable on the X axis. When you're looking at line B, I'd like you to compare the temperature of line B to line C and D. See if you notice any changes and for C, I'd like you to look at the concentration of carbon dioxide in line B, C, and D. See if you notice any changes, pause your screen here complete your answer, and come back when you're done. The answers are now onscreen, go ahead pause your video, mark and feedback your answers and come back when you've finished. Now that you've marked and provided feedback for your responses, let's have a look at the answers a little bit more closely. At point A, light intensity is the limiting factor, We know this because it has a sufficient amount of temperature and carbon dioxide, but as light intensity is on the independent variable or on the X axis, we can see that as the X axis continues to increase, so does the rate of photosynthesis. At point B, we know that temperature is the limiting factor and that there is plenty of light intensity and plenty of carbon dioxide, but the temperature is only at 20 degrees. We can see that the rate of photosynthesis was best when the temperature was at 30 degrees. In point C carbon dioxide is the limiting factor, at this point, the concentration of carbon dioxide is 0.1, but in the most optimal rate of photosynthesis we can see that the concentration of carbon dioxide is 0.2. Excellent work, you've made it to the end of your mid topic review. At this point, you should feel confident stating the photosynthesis equation in both word and symbol form. You should know the five uses of glucose, you should be able to recall the three variables from the required practical, and you should be able to state and identify the four limiting factors of photosynthesis on a graph. Next lesson, we'll begin the second half of the topic which is going to be looking at respiration. See you then.

Worksheet: Review photosynthesis

Exit Quiz: Review photosynthesis

Lesson summary: Review photosynthesis

In this lesson we will review the key concepts of photosynthesis that we have covered so far in this unit.

Combined Science

Y10 Combined Science (Foundation)

Key Stage 4

Year 10

Miss

Review photosynthesis

Bioenergetics (FT)

UNIT

Photosynthesis

Photosynthesis required practical

Photosynthesis required practical results

Limiting factors of photosynthesis

Respiration

Anaerobic respiration

Metabolism

Synoptic links

End of topic review


Exam Skills

Maths Skills

Scientist case study-Ynes Mexia

Biology

Y10 Biology

Bioenergetics

Manipulating factors of photosynthesis HT

Consequences of anaerobic respiration

Y10 Combined Science (Higher)

Bioenergetics (HT)

This quiz will summarise the knowledge you have learned so far in unit 4. 

Mid-topic Review Exit Quiz

What is the correct word equation for photosynthesis?

Which of the following is NOT a limiting factor of photosynthesis?

Glucose is used to make cell walls, what are cell walls made of?

Which of the following is NOT a use of glucose?

What gas is produced in the bubbles during the photosynthesis required practical?

Combined Science

Review photosynthesis

Video

Worksheet

Mid-topic Review

Question 1

Question 2

Question 3

Question 4

Question 5

Q1.What is the correct word equation for photosynthesis?

Q2.Which of the following is NOT a limiting factor of photosynthesis?

Q3.Glucose is used to make cell walls, what are cell walls made of?

Q4.Which of the following is NOT a use of glucose?

Q5.What gas is produced in the bubbles during the photosynthesis required practical?