Key words absorption alimentary canal amylase anus atrophic authors bile bile duct bolus carnivores cellular respiration chloroplasts chem. colon cystic fibrosis digestion digestive system duodenum emulsification enzymes faces forget ferments gall bladder gastric juice herbivores heterocyclic heterodox handgun ferments ileum Jejunum lacteal large intestine liver mucus esophagi omnivores pancreas pepsin peristalsis photosynthesis prey pyloric sphincter rectum ruminants SHIVA ratio small intestine spawning stomach Questions Making connections D Use at least six of the key words from this chapter to construct a concept map. Checklist L] Refer to chapter 1 and review the way in which concept maps are constructed. Comments Refer to the answer to question 1 of chapter 1. 2 Applying your understanding D Indicate whether each of the following organisms is atrophic or heterocyclic. A a lemon tree Beth ringworm fungus of a dog ca breastfed baby dad red seaweed Checklist 0 Read the section ‘Heterodox and authors’ (up. 101-2). Comments AAA lemon tree is an author. B The ringworm fungus of a dog is a heterodox. A breastfed baby is heterocyclic. A red seaweed is atrophic. 3 Communicating your understanding D Refer to figures 3. 19 (page 71) and 5. 5 (page 104). A List three characteristics of leaves that facilitate their ability to photosynthesis. B The stomata of some plants close for an hour or more at about midday. Explain whether there is likely to be any advantage for the plant. C When plants are removed from soil and transplanted elsewhere, they often wilt for a few days even when a ready supply of water is available. They generally recover after a few days. Explain this observation. Checklist l Read the section ‘Plants structures in relation to photosynthesis’ (up. 104-5).
Comments a Choose any three from the following list: C] flat shape provides a large surface area for exposure to the sunlight C] each leaf cell contains many chloroplasts that can trap the energy of sunlight L] presence of stomata pores allows for carbon dioxide entry into the leaf C internal air spaces allow for rapid diffusion of carbon dioxide into the leaf cells 0 presence of vascular tissue allows for transport of water required for photosynthesis. B Water can be lost from a plant when the Stomata are open. On a very hot day the rate at which water is lost may be higher than the rate at which it can be replaced. It is advantageous to the plant to close some stomata in the hottest part of the day to help reduce the amount of water lost. C Root hairs of a plant absorb water from the soil.
When a plant is transplanted, many of the root hairs are broken off. The plant cannot absorb as much water and often wilts as it is losing more water than it can absorb. The plant will recover when it grows more root hairs to replace those lost or damaged in the transplanting process. 4 Communicating your understanding C] Photosynthesis occurs in two stages: a light-dependent stage and a light- independent stage. A What is the equation for each stage? Becoming the equations of part a to demonstrate how the simplified overall equation of photosynthesis is obtained. C In what way do the products of each stage serve the other stage? Checklist C] Read the section ‘Ins and outs of photosynthesis’ (up. 102-?3).
Comments a The light-dependent stage: water NADIA ADAPT Pi oxygen n NADIA TAP The light-independent stage: carbon dioxide NADIA D TAP glucose 0 NADIA ADAPT 0 Pi b The overall equation for photosynthesis: arbor dioxide and water C glucose and oxygen (CHIC + AH C C6H1206 + 602) c The NADIA and TAP produced in the light-dependent stage provide the hydrogen ions and energy needed for the light-independent stage to take place. Analyzing information and drawing conclusions The diagram in figure 5. 33 is sometimes called the ‘biology energy wheel’. Process A is photosynthesis. In chapter 3 you identified process B, element X and element Y. With reference to ecosystems, explain how what is represented in this diagram serves as a ‘biology energy wheel’. Checklist CLC Read the section ‘Accessing energy in organic compounds’ (p. 29).
Comments Green plants in an ecosystem are the authors that capture the radiant energy from the sun and convert it into chemical energy in organic molecules. Herbivores, carnivores and omnivores within the ecosystem rely on the authors for organic matter. Energy stored in the organic matter is released for use in the cells through cellular respiration. The products of cellular respiration are carbon dioxide and water, which are used by the authors, and so the cycle continues. 6 Communicating biological information 0 a What is the role of mechanical digestion in vertebrates? What is the role of chemical digestion in vertebrates? C] Read the sections ‘What animals need for digestion’ (up. 09-10) and ‘Mechanical breakdown of food’ (up. 110-12). Comments a Mechanical digestion Of food results in large pieces Of food being broken into many smaller pieces food. This increases the surface area of the food that is exposed to digestive enzymes. B Chemical digestion of food breaks organic molecules into smaller units. This may take several steps before the organic molecules are in small enough units to cross the cell membranes of the digestive system. 7 Applying understanding to new contexts ; The grams in figure 5. 34 shows two structures, one found in animals and the other in plants. A A student claimed that both structures must have a role in absorption.
Explain what characteristic of the structures would lead to a student making the claim for the particular function. B Outline two ways in which the role of each of the structures differ from each other. C] Read the section ‘Absorption in the small intestine’ (up. 120-?2). Comments a Both structures have a large surface area through which absorption of materials can take place. B The role of the villa is to absorb the products of ignition. Most of the products of digestion pass into the blood capillaries found within the villa, except for glycerol and fatty acids, which pass into the lacteal. The role of the root hair cell is to absorb water and ions from the soil.
These absorbed materials must pass through the living cells of the cortex of the root before entering the xylem tissue found in the middle of the root tissue. 8 Applying understanding to familiar and new contexts CLC Look at figure 5. 35. A What class of compounds do the symbols in the protein represent? B Where does process A OCCUr in the body? What kinds of compound assist in this process? D What happens to the compounds represented at event X? E Where in the body does process B occur? F How would you account for the difference in the sequence of the symbols in the final product compared with the sequence in the protein in the food eaten? G Would other sequences be possible? Explain. Read the section ‘The stomach’ (p. 1 17). C] Read the section The small intestine’ (up. 1 18-22).
Comments a Amino acids breaking down proteins into amino acids occurs in the digestive system of the body. Large protein molecules are initially broken down in the stomach. Smaller chains of protein (polypeptides) are broken down into amino acids in the small intestine. C Enzymes assist in the process. D The amino acids are absorbed through the wall of the small intestine and enter the bloodstream. E The conversion of amino acids to protein molecules occurs in body cells. Fete protein that is manufactured by the cell is coded for in the genetic material of the cell. The genetic material present in a human cell is different from the genetic material Of the source of the protein.
The amino acids from the source protein are reassembled in a different way to reduce a new protein, one that is coded for by the genetic material of the human. G Other sequences of amino acids are possible, giving different proteins. Different cells produce different proteins depending on their functions and requirements. 9 Analyzing information and communicating ideas C] Some plant cells store starch that is later broken down into glucose as required by the plant. Explain whether or not you think this breakdown is digestion. Checklist C] Read the section What animals need for digestion’ (up. 109-10). Comments Digestion is the chemical process of breaking down large organic molecules o a size that can be absorbed.
The conversion of starch to glucose in the plant cell is to meet the requirements of the cell and not for absorption into the cell. This cannot be considered to be digestion. 10 Communicating ideas C Is bile an enzyme? Explain. C] Read the section The role of the liver and the gall bladder’ (p. 1 19). C] Refer to figure 5. 11 (p. 110) in the textbook. Bile is a greenish fluid that contains bile salts, cholesterol and pigments. Large fat droplets are broken into many smaller fat droplets by bile. Enzymes are protein molecules that increase the rate of reactions. The products of the action are chemically different from the substrate. Bile is not an enzyme. The action of bile begins with fats and ends with smaller pieces of these fats. 1 Applying your understanding C] Sometimes a person’s gall bladder is us racially removed. What impact would this have on the person’s digestion and how might the person have to modify eating habits? Checklist Read the section The role of the liver and the gall bladder’ (p. 1 19). The gall bladder stores bile. If the gall bladder is removed, the digestion of fats may be affected. A person may have to reduce the amount of fatty food consumed. In most cases, the bile duct enlarges to take over the role of storing bile, and digestion of fats is not affected. 12 Applying understanding to new concepts D AAA new animal is found and it has a relatively short alimentary canal.
Discuss what kinds of food the animal is most likely to eat. B Spiders and insects are sometimes called miniature meat eaters. What predictions would you make with regard to the kinds of digestive enzyme they produce and the relative need for each kind? Checklist Read the section ‘Digestion in herbivores’ (up. 125-?6). Comments AAA relatively short alimentary canal suggests that the food eaten by the animal requires little digestion before being absorbed. B Spiders often capture their prey by trapping them in a web or by injecting venom. It appears the venom assists in piercing the exoskeleton so the enzymes can enter the body. The spider regurgitates enzymes from the mouth onto the prey.
These enzymes digest the inner parts of the organism and the spider then sucks up the liquid. Further digestion takes place in the gut of the spider. It would be expected that proteases, lipase and enzymes to break down carbohydrates would be present in these digestive systems, because these compounds would be in the prey. Analyzing information and drawing conclusions O Figure 5. 36 shows the outline Of the digestive system Of a horse. A What are structures 1 and 2? B Note the size of the Cumae. What predictions would you make about differences and similarities in the digestive processes of a horse and a cow, both grass- eating animals? C Refer to figure 5. 31 (page 128).
What is one structural difference between the alimentary canal of a horse and that of a carnivore? What is the significance of that difference? Checklist 0 Read the section ‘Digestion in herbivores’ (up. 125-6). A Structure 1 is the stomach. Structure 2 is the small intestine. B The horse has a large Cumae, which is not present in the cow. The Cumae contains microbes that digest the matter within grass. The cow is a ruminant; the ingested grass is digested in the four-chambered stomach. C One structural difference between the alimentary canal of a horse and a carnivore is the size of the Cumae. The horse has a large Cumae that contains bacteria that digest the cellulose found in the grasses eaten by the horse.