1. Previously…

2. Photosynthesis is… The process by which plants use carbon dioxide, water and light trapped by chlorophyll to make food in the form of glucose, with oxygen being given off during the process. + +

3. Photosynthesis The process in word equation… Carbon dioxide Water + Light chlorophyll Oxygen Glucose +

4. Conditions essential for photosynthesis Sunlight (light energy) Light energy is converted to chemical energy stored in glucose. Suitable temperature Photosynthesis depends on the reactions of enzymes in the chloroplasts. Enzyme reactions are fastest at a suitable temperature. Chlorophyll This green pigment absorbs light energy and changes it into chemical energy needed to manufacture glucose. Carbon dioxide and water These are the raw materials needed to form carbohydrates (glucose). water glucose

5. Importance of photosynthesis Why is photosynthesis important? - Photosynthesis makes chemical energy available to animals - Photosynthesis removes carbon dioxide and provides oxygen.

6. Photosynthesis makes chemical energy available to animals All living organisms need energy to move, grow, excrete, reproduce and maintain themselves. Video: energy

7. Photosynthesis makes chemical energy available to animals What is the ultimate source of energy for animals? Light energy from the Sun. During photosynthesis, light energy is absorbed by chlorophyll and transformed into chemical energy. Light energy chemical energy chlorophyll

8. Cellular Respiration Chemical energy is locked up in food molecules such as glucose. The chemical energy stored in food molecules is released to living organisms in a process called cellular respiration. Chemical Energy (in food) Energy (for organisms) Cellular respiration

9. Cellular Respiration Cellular respiration takes place in all the living cells of organisms Since living cells need energy to carry out many vital processes all the time, respiration occurs all the time.

10. Cellular Respiration Aerobic Respiration Tissue Respiration External Respiration Anaerobic Respiration Main Focus

11. Aerobic Respiration Aerobic respiration is the process whereby food substances are broken down in the presence of oxygen with the release of energy in living cells. Carbon dioxide and water are released as waste products. Word equation for aerobic respiration: Glucose Oxygen + Water Carbon dioxide + Energy + Video: res in cells

12. Tissue Respiration Tissue respiration is the process by which food substances are broken down in living cells. A large amount of energy is released for the cells to perform different activities. In tissue respiration, glucose combines with oxygen to release energy, carbon dioxide and water. Glucose Oxygen + Water Carbon dioxide + Energy +

13. External Respiration External respiration is the process of bringing the oxygen from the surrounding environment to the cells for tissue respiration to take place.External respiration is the process of bringing the oxygen from the surrounding environment to the cells for tissue respiration to take place. External respiration is also responsible for removing from the body the carbon dioxide and water formed during tissue respiration.External respiration is also responsible for removing from the body the carbon dioxide and water formed during tissue respiration. Breathing is part of external respiration.Breathing is part of external respiration.

14. Importance of Aerobic Respiration Most organisms respire aerobically. Energy released is used for: - Growth (building up of proteins) - Muscle contractions (e.g. heartbeats) - Digestion and absorption of food substances - Cell division

15. Aerobic Respiration Do plants carry out aerobic respiration in the day? Yes. Plants carry our aerobic respiration all the time.

16. Aerobic Respiration in Plants During the day, plants photosynthesise. The oxygen produced is more than what is needed for aerobic respiration. The excess oxygen is released to the surroundings. At night, photosynthesis stops. Plants take in oxygen from the surroundings for aerobic respiration and give off carbon dioxide to the surroundings. Video: plant

17. Aerobic Respiration Oxygen is taken in from the surrounding air while carbon dioxide and water are released to the surroundings. In plants, these respiratory gases (oxygen, carbon dioxide & water) are exchanged with the surroundings through the stomata. In humans, the respiratory gases are exchanged with the surroundings using the respiratory system.

18. Human Respiratory System Video: Airway

20. Human Respiratory System Components of the human respiratory system - nose - nasal cavity - pharynx - trachea - bronchus - bronchioles - alveoli - diaphragm - lungs

21. Human Respiratory System Components of the human respiratory system - nose - nasal cavity - pharynx - trachea - bronchus - bronchioles - alveoli - diaphragm - lungs

22. In the nose… Air enters through two external nostrils. The nostrils lead into two nasal passages which are lined with a moist mucous membrane.

23. In the nose… Passing the air through the nasal cavity has the following advantages: 1.dust and foreign particles are trapped by the hairs in the nostrils and by the mucus on the mucous membrane. 2.air is moistened and warmed before it enters the lungs.

24. From the nose to the trachea The air in your nasal passages enters the pharynx. From the pharynx, air passes into your larynx and then into your trachea.

25. The trachea and bronchi The lower end of the trachea divides into two tubes/bronchi. Each bronchus (plural: bronchi) connects to one lung.

26. The trachea and bronchi Each bronchus divides continually and ends in bronchioles. Each bronchiole ends in a cluster of air sacs or alveoli (singular: alveolus). bronchioles alveoli

27. The trachea and bronchi Thousands of alveoli are found in lungs, and these alveoli provide a very large surface area for gaseous exchange. Gaseous exchange is possible because alveoli are well-supplied with blood capillaries. bronchioles alveoli Video: Gas exchange between the lungs and blood

28. The trachea and bronchi Wall of alveolus is one cell thick → faster rate of diffusion of gases through it Thin film of moisture covers surface of alveolus → allows oxygen to dissolve in it bronchioles alveoli

29. Breathing The physical process by which respiratory gases are exchanged with the surroundings. It is also the movement that brings air into and out of the body.

30. Breathing Inhalation / Inspiration - taking in of air from the surroundings

31. Breathing Exhalation / Expiration - giving out of air to the surroundings

32. Breathing Air that we breathe in Inhaled air Air that we breathe out Exhaled air

33. Mechanism of breathing (Enrichment) Case 1:Case 1: When these rib muscles contract, the rib cage expands. The contraction of ribs and diaphragm increases the volume of the chest cavity. The space surrounding the lungs increases so the lungs expand. The pressure of the air of the lungs falls and the air is drawn into the lungs.

34. Mechanism of breathing (Enrichment) Case 2:Case 2: When the diaphragm muscles and the rib muscles relax, the chest cavity becomes smaller and the lungs compress. The pressure of the air in the lungs increases, hence forcing air out again.

35. Inhaled Air & Exhaled Air water vapour (variable) nitrogen (78%) carbon dioxide (app. 0.03%) noble gases (app. 1%) oxygen (21%) nitrogen (78%) water vapour (variable) carbon dioxide (4%) noble gases (app. 1%) oxygen (16%) Composition of inhaled air composition of exhaled air

36. Inhaled Air & Exhaled Air Inhaled airExhaled air OxygenContains 21% oxygenContain 16% oxygen Carbon Dioxide Contain 0.03% carbon dioxide Contains about 4% carbon dioxide Water vapour Contain less water vapour than exhaled air Contain more water vapour than inhaled air.

37. Question Is there more oxygen in inhaled air or exhaled air? Why? Is there more carbon dioxide in inhaled air or exhaled air? Why? Is there more water vapour in inhaled air or exhaled air? Why? Video: Composition of air

38. Respiration & Photosynthesis Both photosynthesis and aerobic respiration are complex processes that are alike in several ways. But in many ways, they are also different.

39. Respiration & Photosynthesis RespirationPhotosynthesis Uses oxygenProduces oxygen Does not need chlorophyllNeeds chlorophyll Uses foodProduces food Produce carbon dioxideUses carbon dioxide Takes place all the timeRequires sunlight Takes place in all living thingTakes place in green plants Takes place in all living cellsTake place in cells containing chlorophyll Video: respiration

40. Respiration & Photosynthesis RespirationPhotosynthesis Energy is liberated Energy is stored in carbohydrate molecules Oxygen is used and carbon dioxide and water are given off Carbon dioxide and water are used and oxygen is given off A destructive process, resulting in the breakdown of carbohydrate molecules. A constructive process, resulting in the building up of carbohydrate molecules. Occurs at all times in all cells, independent of chlorophyll and sunlight Occurs only in cells containing chlorophyll and in the presence of sunlight -Both involve energy. -Both involve enzymes.

41. Anaerobic Respiration Anaerobic respiration is the breakdown of food substances in the absence of oxygen. Anaerobic respiration releases less energy than aerobic respiration. Word equation for anaerobic respiration in humans: Word equation for anaerobic respiration in yeast: Glucose Ethanol Carbon dioxide + Energy + Glucose Lactic AcidEnergy+

42. Anaerobic Respiration Some bacteria are anaerobic. Anaerobic respiration in yeast is known as alcoholic fermentation - yeast respires anaerobically to convert sugar to alcohol in the fermentation process.