The-importance-of-water-in-transport.pptx

A level Biology

1. Water Pearson Edexcel A-level Biology A 1.1 The importance of water in transport

2. Chambers in the human heart 0.080mm in µm Chromosomes in a human body cell x 2 Characteristics of living organisms x 10 Main types of blood vessels You could say that the numbers are raining down at the start of this lesson because the answers to these biological clues are all numbers associated with WATER . Start this lesson by calculating these 5 numbers but be sure to keep them to yourself for now

3. Today’s 1 st round is a lengthy one as it runs throughout the whole lesson and it will make use of those 5 numerical answers. This is DROP by DROP! 1.2 QUIZ R1

4. DROP by DROP! This round of the quiz will run throughout the course of the lesson so keep your eyes peeled for this title and background. In each edition, a clue associated with a property, a role or the structure of water will appear on the board and the answer is one of the 5 numbers which you calculated at the beginning of the lesson. Simply buzz in when you’ve identified the numerical answer and if you’re 1 st and correct, you’ll get 1 TEAM POINT. However, be aware that any wrong answers will be met with the loss of a TEAM Point.

5. Percentage of cytoplasm that is water DROP by DROP! 80

6. Water is a major component of a cell, where it can constitute up to 80% of the cytoplasm and this alone is enough to indicate its importance as a biological molecule in living organisms. The rest of this lesson focuses on the relationship between the properties of water and one of these critical roles; transport in animals….

7. Atoms in a molecule of water DROP by DROP! 3

8. Prior knowledge check (GCSE) A molecule of water contains one oxygen atom and two molecules of water By verbalising your answer to a partner, challenge your recall of GCSE Chemistry by naming the type of bond that will be found between the oxygen and hydrogen atoms (1 mark)

9. WATER KEY POINT One molecule of water contains an atom of oxygen covalently bonded to two atoms of hydrogen

10. O H H O H H O H H KEY covalent bond

11. Round 2 challenges your Biology, Maths and “English” skills as you have to convert FROM NUMBERS 2 LETTERS 1.2 QUIZ R2

12. FROM NUMBERS 2 LETTERS There will be two editions of this round over the next part of this lesson. In each edition, there will be a series of statements which have numerical answers and each number corresponds to a letter of the alphabet (e.g. If the number is 6, the letter is F) Your challenge is to convert FROM NUMBERS 2 LETTERS and to be the 1 st to buzz in with a prefix or key term. The reward for a correct answer is 2 TEAM POINTS FROM NUMBERS 2 LETTERS

13. (% of cytoplasm that is water) ÷ 5 (Main types of blood vessel) x 5 Hydrogen atoms in a molecule of glucose Parent cells involved in asexual reproduction ( Legs on an insect) x 3 FROM NUMBERS 2 LETTERS P O FROM NUMBERS 2 LETTERS L A R

14. Since oxygen has a higher electronegativity than hydrogen, the side of the molecule with the oxygen atom has a slightly negative charge and the side with the hydrogen atoms has a slightly positive charge. As there is an uneven distribution of charge throughout the molecule, water is described as a polar molecule and more specifically as having a dipole nature because of the charge difference at the two ends. You can annotate a diagram of water molecules with this symbol, δ , and either a positive or negative sign after it to denote charge

15. LINK TO THE FUTURE As you move through the A-level course, you will become acutely aware of the term polar and its importance. For example, at the start of topic 2 you will learn that only those molecules that are small and non-polar are able to move by (simple) diffusion across the partially permeable membrane without assistance. This is because the main component of a cell membrane is a phospholipid and this has a phosphate head which is polar and fatty acid tails that are non-polar

16. Bonds are extremely important for the structure, properties and roles of biological molecules and a selection of the bonds that you will meet in topic 1 & 2 are shown below. Study the diagram of the water molecules and then predict which of the 007 bonds shown below will be the one to be found between water molecules Peptide Ionic Glycosidic Phosphodiester Disulfide Ester Hydrogen The name’s bond, __________ bond HYDROGEN Form between water molecules

17. O H H δ + δ - δ + O H H δ + δ - δ + O H H δ + δ + δ - Hydrogen bonds form between the slightly negatively charged oxygen of one molecule and the slightly positively charged hydrogen of another molecule KEY covalent bond Hydrogen bond

18. This might just prove useful…… A substance that is useful for comparison purposes is hydrogen sulphide (H 2 S). As this compound has double the molecular weight of water, you might expect it to have the higher boiling point of the two compounds. However, H 2 S is in fact a gas at room temperature whereas we know that H 2 O is a liquid and this can be explained by the presence of hydrogen bonds which take a considerable amount of energy to break and are only found between the molecules in water.

19. WATER KEY POINT The attraction between molecules, known as hydrogen bonding, is paramount to the properties of water

20. (Chromosomes in a human egg cell) - 4 (Chromosomes in a human egg cell) - 8 (Legs on a spider) x 1.5 FROM NUMBERS 2 LETTERS S O FROM NUMBERS 2 LETTERS L

21. Read through the 5 crossword clues which describe 5 words that all begin with SOL. The letters of the word which is strongly associated with water should be written in blue and the letters of the other 4 words written in red YOUR TASK

22. S S S S O O O O O L L L L L O L L V E N T U T U T I N B E U B I T Y The SOL utions

23. WATER KEY POINT Water is an important solvent in which metabolic reactions occur

24. Percentage of the volume of blood plasma that is water DROP by DROP! 92%

25. One of the key challenges of any A-level Biology course are the application questions. Fill in the value for the % of water in blood plasma in question 3 and then challenge your ability to answer this kind of question YOUR TASK

26. Both aerobic and anaerobic respiration need glucose as a reactant. Following the absorption of this simple sugar into the bloodstream (through the lining of the small intestine), glucose has to be transported to the cells and it does this by dissolving in the blood plasma

27. Biological knowledge check Glucose is transported in the bloodstream by dissolving in the blood plasma By verbalising your answers to a partner, name two more molecules that dissolve in the water in blood plasma to be transported around the body (2 marks) mineral ions, urea, carbon dioxide, hormones

28. In case you are interested…… As well as transporting substances like glucose and urea around the body, the blood (and its high water content) is also involved in thermoregulation. When an increase in body temperature is detected by the thermoreceptors, one particular response is vasodilation where the arterioles and precapillary sphincters ensure that a greater volume of blood flows along the blood vessels near to the skin. This increases the rate of energy loss by radiation and in combination with some other physiological and behavioural responses, the result is that the body temperature decreases to within the normal range

29. A physiological response to an increase in body temperature is vasodilation Vasodilation isn’t the only physiological response to an increase in body temperature that involves water so use this short period of time to identify another process 1 TO THINK ABOUT You have 2 minutes to discuss with 1 person A key physiological response to the detection of an increased body temperature is an increase in the secretion of sweat from sweat glands onto the surface of the skin But why does an increased production of sweat help with thermoregulation? You have 2 more minutes to try to think of a specific term from IGCSE Physics which might help to explain how the evaporation of water from the skin will result in a cooling effect

30. This might just prove useful…… The latent heat of vaporisation is the energy transferred when 1kg of a substance changes from the liquid state to a gas

31. WATER KEY POINT Water has a relatively large latent heat of vaporisation

32. Complete the passage in question 4 which uses a biological example to describe the importance of water’s high latent heat of vaporisation YOUR TASK

33. If an increase in body temperature is detected by the thermoreceptors, the body responds by increasing the secretion of sweat onto the skin’s surface. As water has a high latent heat of vaporisation, a lot of heat energy has to be transferred from the body to break the hydrogen bonds between the molecules to cause water to evaporate into a gas . This has a cooling effect on the body and causes the temperature to return to within the normal range

34. This task has been designed to challenge your observational skills. You will be shown two separate diagrams, but each one will only remain on the board for 30 seconds. The diagrams are connected and you need to spot the difference between the 1 st and 2 nd diagram OBSERVATIONAL TASK

35. What did you SEE?

36. A condensation reaction joins two molecules together with the formation of a chemical bond, and involves the elimination of a molecule of water WATER KEY POINT

37. We have finally reached the 3 rd and final round of the competition and as you should always try to do in Biology, it’s time to MAKE THE LINK! 1.2 QUIZ R3

38. MAKE THE LINK This round of the competition is split into two and will result in the introduction of the name of another important reaction involving water. In the first part, the end of three scientific words which have the same prefix will appear on the board and all you need to do is to identify their common prefix . When you’ve got it, buzz in and a correct answer will get 2 TEAM POINTS The second part is exactly the same apart from this time, the start of three scientific words are shown and the 2 TEAM POINTS will be awarded to the 1 st to buzz in with the common suffix

39. hydro…. …..e lectric …..s tatic …..gen MAKE THE LINK

40. …..lysis e lectro ….. glyco ….. haemo ….. MAKE THE LINK

41. Write a definition for a hydrolysis reaction [2 marks] Copy this question next to number 5 and then use the fact that a hydrolysis reaction has the opposite effect of a condensation reaction to write a 2 mark answer YOUR FINAL TASK

42. A hydrolysis reaction breaks a chemical bond between two molecules and involves the use of a water molecule WATER KEY POINT

43. LINK TO THE FUTURE A lot of the topic 1 & 2 lessons and actually most of the other topics in this A-level course will require you to be confident in your recognition of condensation and hydrolysis reactions . For example, you’ve just seen how two molecules of α -glucose join together during a condensation reaction to form a disaccharide called maltose which is held together by a 1 – 4 glycosidic bond. Conversely, this sugar could be broken back down into the two monomers during a hydrolysis reaction which is catalysed by maltase

44. Chambers in the human heart 80% of cytoplasm is water 9 2% of the volume of blood plasma is water Characteristics of living organisms x 10 A water molecule contains 3 atoms So that just leaves 4 and 70. 4°C is the temperature at which the density of liquid water peaks whereas 70 is the percentage of the Earth’s surface that is covered in water . 4 70

45. In case you are interested…… The fact that the solid form of water has a lower density than the liquid form explains why ice floats. This coupled with the high specific heat capacity of water ensures a stable environment for aquatic animals like fish as well as providing a habitat for animals like polar bears that live on the ice