Unit 1; Area of Study 2

1. Unit 1; Area of Study 2 Functioning Organisms

2. Chapter 5 Obtaining Energy and Nutrients for Life

3. WEEK 6: Obtaining Nutrients LEARNING OUTCOMES By the end of this week, you should be able to explain: • Biochemical processes including photosynthesis and cellular respiration in terms of inputs and outputs. • Obtaining nutrients: organic and inorganic requirements; autotrophs; heterotrophs. • Obtaining energy: inputs and outputs of photosynthesis; structural features of photosynthetic organisms. • Processing nutrients: features of effective systems in heterotrophs; examples of systems in different animals.

4. LESSONS 1-2: Heterotrophs, autotrophs and photosynthesis LEARNING OUTCOMES By the end of these lessons, you should be able to: • Define ‘autotroph’ and ‘heterotroph’. • Distinguish between heterotrophs and autotrophs in terms of nutrient requirements for life. • Summarise the process of photosynthesis in a word equation and chemical equation. • Identify structural features of photosynthetic organisms that facilitate their ability to photosynthesise.

5. Active and Passive • What do the terms mean? • Watch the clip.... • Is the whale shark an active feeder or a passive feeder?

6. Heterotrophs • Actively obtain the energy they need for life by feeding on organic matter found in their surroundings (food!) • They then use this organic matter to build and repair their cells. • Give some examples... • What structural, physiological and behavioural adaptations do heterotrophs have to help them obtain their food?

7. Autotrophs • Organisms that just take up (absorb) the energy they need from their surroundings. • They build organic matter from simple inorganic matter taken up from the air, soil or water. • Give some examples.....

8. So what about these guys...?

12. Carnivorous Plants • Carnivorous plants still need water and sunlight like other green plants to make food/energy (glucose) but they get their mineral nutrients from trapping and consuming animals. • Carnivorous plants are adapted to grow in places where the soil is thin or lacking nutrients, especially nitrogen, such as acidic bogs and rock outcroppings.

14. Photosynthesis • Plants, algae and some protists can make sugars by photosynthesis. • Sunlight energy is converted into chemical energy (in the form of glucose) in the chloroplasts found in the cytosol of cells.

15. What do you know already?

16. Plants use the energy from the sun to make molecules such as glucose, starch and proteins. • These molecules can then be used for food for the plant, but also for animals like us. • A waste product of the process is oxygen, which is released into the atmosphere.

17. The Importance • The importance of photosynthesis is in the conversion of unusable sunlight energy into usable chemical energy (glucose). • It is one of the most important biochemical processes,since nearly all life on Earth either directly or indirectly depends on it as a source of energy.

18. The Equation Word equation: Balanced chemical symbol equation: light carbon dioxide + water glucose + oxygen chlorophyll light 6CO2 + 6H2O C6H12O6 + 6O2 chlorophyll

19. Or: six molecules of water plus six molecules of carbon dioxide produce one molecule of sugar plus six molecules of oxygen.

20. Plants absorb water through their roots, and carbon dioxide through their leaves. • Some glucose is used for respiration, while some is converted into insoluble starch for storage. • The stored starch can later be turned back into glucose and used in respiration.

21. Testing a green leaf for starch • Will a plant that has been kept in a dark cupboard for a few days contain starch in its leaves?

22. Structure of the Leaf • Photosynthesis takes place mainly in the cells of the leaves. • Leaves are well adapted for photosynthesis – its structure is well suited to its function. • Leaves are made up of four main layers: • Upper epidermis • Palisade layer • Spongy layer • Lower epidermis Mesophyll layer

23. Inside the leaf

24. Structure of the Leaf • Waxy cuticle • Vein/vascular bundle • Air space • Stoma • Guard cell • Upper epidermis • Lower epidermis • Palisade cell • Spongy mesophyll cell Label the diagram with the structures:

25. Waxy cuticle Vascular bundle (vein) – xylem and phloem Upper epidermis Palisade cell Spongy mesophyll cell Air space Lower epidermis Guard cell Stoma

26. A B C D E F G H I

27. Epidermis • Single layer of cells on the upper and lower surfaces of the leaf. • Helps to keep the leaf’s shape. • Has closely fitting cells: • Reduces evaporation from the leaf • Prevents bacteria and fungi from getting in • Thin waxy layer covering epidermis called the cuticle – helps to reduce water loss further. • Have stomata. • In woody stems, the epidermis is bark.

29. Stomata • Singular: stoma • Structures in the leaf epidermis. • Consists of a pair of guard cells, surrounding an opening called the stomatal pore. • The stomata can open and close by changes in the turgor and shape of the guard cells. • In some plants they are located on the lower epidermis only, others have stomata on both sides of the leaf.

30. Stoma Guard cell Leaf epidermal cell

31. How Do Stomata Work? • Generally, they open during daylight hours (whilst photosynthesis is taking place) and close during the night. • Why? • What do plants need to photosynthesise? • During the day they are open to allow carbon dioxide to diffuse into the leaf (and oxygen out) so photosynthesis can take place.

32. Mesophyll • Tissue between the upper and lower epidermis. • Consists of two layers (see diagram). PALISADE CELLS: • Function – to make food by photosynthesis. • Hence, they have lots of SPONGY MESOPHYLL CELLS • Vary in shape, and fit loosely together. • Many air spaces between them. chloroplasts.

34. Air Spaces • Whilst photosynthesis is taking place, the air spaces in the mesophyll layer fill with carbon dioxide as it enters the leaf, and oxygen as it leaves the leaf.

35. Veins (vascular bundles) • Xylem vessels carriy water needed for photosynthesis to the mesophyll cells. • The mesophyll cells take in water through osmosis. • Branching network – no cell is far away from a water supply. • Sugars made in mesophyll cells are passed to the phloem cells – carry sugar away from the leaf to the stem.

37. The Ins and Outs of Photosynthesis • There are two stages of photosynthesis: • A light dependent stage – needs water, light and chlorophyll. Gives off oxygen as a waste product. • A light independent stage – needs the products (hydrogen and energy) from the first stage, as well as carbon dioxide. Simple sugars are made. • Look at textbook pages 96-97 , and draw a simplified diagram to show the inputs and outputs of the two stages of photosynthesis.

38. When is photosynthesis most efficient? • Chlorophyll absorbs redlight best, followed by blue. Green light is reflected, so not absorbed. Therefore photosynthesis is most efficient in red light, and least in green. • When these limiting factors are taken into account, photosynthesis can occur at the quickest rate: • light intensity is high • carbon dioxide concentration is high • temperature is ‘warm’ – not too hot as enzymes denature • adequate water is provided.

39. LESSONS 3-4: Cellular Respiration and Digestion LEARNING OUTCOMES By the end of these lessons, you should be able to: • Understand and explain the inputs and outputs of the significant stages in cellular respiration. • Understand the systems for processing nutrients in a range of different heterotrophic organisms.

40. ATP • Adenosine triphosphate • The form of energy used to maintain cellular functions – like photosynthesis and respiration. • Made in the mitochondria where respiration takes place.

41. Respiration • Respiration transfers chemical energy in the form of glucose into ATP. • Aerobic respiration uses oxygen. • Anaerobic respiration occurs without the presence of oxygen – less energy is released. In human muscles, lactic acid is produced.

42. The Equation ATP ADP + Pi glucose + oxygen carbon dioxide + water C6H12O6 + 6O2 + H2O 6CO2

43. Digestion • The chemical process of breaking down large organic molecules to a size that can be absorbed by the body. • Generally, four steps of digestion occur before a substance can become available for use by the cells of an animal: • Ingestion • Mechanical breakdown • Chemical breakdown • Absorption

44. The Four Steps • Ingestion – intake of food into the mouth. • Mechanical breakdown – break down of food involving moving parts of the body. Occurs in two parts, firstly by chewing in the mouth and secondly by the churning of the stomach, mixing the food around. • Chemical breakdown – secretion or various digestive enzymes onto the food particles to further break down food particles into smaller and smaller particles. • Absorption – organic molecules pass through the lining of the intestinal walls into the blood stream to be distributed to cells.

45. Mechanical Breakdown Jaws and teeth • The jaws surround the mouth and are opened and closed by muscles. • Movement of toothed jaws breaks food down into smaller pieces. • The structure of the teeth and jaws relates to the diet of the animal. • What are some examples?

46. Kinds of teeth • There are four different kinds of teeth found in most mammals: • Incisors: cutting/clipping teeth found at the front of the mouth, used predominantly by herbivores and omnivores. • Canines: well developed in carnivores, specialised for tearing flesh from bones. • Premolars: smaller than molars, flattened teeth used for grinding food. • Molars: large flattened teeth used for grinding food.

47. Differences in teeth arrangements • Fig 5.14 on page 106 – Different teeth arrangements in some animals • Copy key ideas and answer quick check questions on p 106

48. The Digestive System Class task – group work (2-3 people per topic) presenting the different parts of a typical vertebrate digestive system: • The mouth and oesophagus • The stomach • The liver and gall bladder • The pancreas • The small intestine (duodenum) • The small intestine (jujenum and ileum) • Absorption in the small intestine • The large intestine, rectum and anus

49. LESSON 5: Types of Digestive System LEARNING OUTCOMES By the end of this lesson, you should be able to: • Understand and explain the systems for processing nutrients in a range of different heterotrophic organisms.

50. Digestion in Herbivores • Herbivores are animals that only eat plant matter. • Cellulose is the major carbohydrate found in plants, but it indigestible by animals. • Cellulose can only be broken down (fermented) by bacteria, and so all animals that eat plant matter have bacteria living in their gut. • Depending on where the bacteria live in the gut, herbivores are classified into two groups: • Foregut fermenters or • Hindgut fermenters