3 . G11 LifeSciences DigitalSupport web Life Processes in Plants and Animals

Study & Master Support Pack | Grade 11 CAPS Life Sciences Life processes in plants and animals This support pack for the Life processes in plants and animals strand of the Life Sciences Grade 11 CAPS curriculum provides revision summaries on the topic to help prepare for the examinations. Learners can work through these individually at home or these could form the basis of a catch-up class or online lesson. You have permission to print or photocopy this document or distribute it electronically via email or WhatsApp. Cambridge University Press Africa is a proudly South African publisher. For more information on our Study & Master CAPS-approved textbooks and valuable resource materials, visit www.cambridge.org Brighter thinking | Better learning www.cambridge.org

UNIT 1: Photosynthesis formation of food storage of in chloroplasts manufactured food temperature carbon dioxide trapping and release of storing energy oxygen improving crop yields in greenhouses by CO2 light enrichment, optimum intake of raw light and materials dark phases light and temperature Photosynthesis: Rate of photosynthesis process and importance Role of ATP as an important Photosynthesis energy carrier in the cells

UNIT 1 Photosynthesis • Photosynthesis is a process in which enzymes are used to build up complex products from simple substrates – a biosynthetic or anabolic (building-up) process. • Photosynthesis takes place in special organelles in the cell called chloroplasts. • These equations describe the process of photosynthesis: chlorophyll Carbon dioxide + water + light → glucose + oxygen enzymes This equation can also be illustrated by symbols as follows: chlorophyll CO2 + H2O + light → C6H12O6 + O2 enzymes • Photosynthesis requires light (radiant energy), water, carbon dioxide, chlorophyll and enzymes, and produces oxygen and glucose. • Photosynthesis takes place in the green parts of the plant, mainly in the leaves, in organelles called chloroplasts. • Chloroplasts contain the pigment chlorophyll, which traps light energy. The importance of photosynthesis • Photosynthesis is important because the process releases oxygen into the atmosphere, uses carbon dioxide and traps energy for food production. Factors affecting the rate of photosynthesis • The rate of photosynthesis is determined by environmental conditions such as temperature, light intensity and carbon dioxide concentration. • Food producers such as farmers use their understanding of photosynthesis to improve the growth of crops in greenhouses. The role of adenosine triphosphate (ATP) • ATP is the major energy carrier of the cell, providing the energy for most of the energy-consuming activities of the cell.

UNIT 2: Animal nutrition (mammals) structure and hepatic portal importance of villi system carbohydrases, incorporation of proteases, lipases role of the liver small intestine glucose and amino acids into cells chemical digestion: diabetes enzymes peristalsis absorption assimilation hormonal control of mechanical or blood sugar levels chewing physical digestion Homeostatic control types and functions of different types of teeth Nutritional processes and significance of relationship between tooth decay food intake, energy, related to functions of different parts growth and health diet requirements Animal nutrition Human nutrition (mammals) malnutrition different diets structure of alimentary dietary canal and associated organs supplements Dentition differences in terms of Alcohol and drug abuse nutritional requirements and energy relationships herbivores dangers associated omnivores carnivores effects with their misuse

UNIT 2 Animal nutrition (mammals) Herbivores, carnivores and omnivores • Herbivores, carnivores and omnivores have different dentition because of their different diets and lifestyles. Human nutrition • Humans have a two-ended (two-opening) digestive tract or alimentary canal. The digestive system can be divided into a tubular alimentary canal and accessory organs. • Each section of the human digestive tract is very specialised; each performs its own function. nasal cavity palate tongue bolus of food salivary duct epiglottis salivary gland trachea oesophagus diaphragm liver sphincter muscle gall bladder bile duct stomach sphincter muscle pancreas pancreatic duct duodenum small intestine ileum caecum colon appendix large intestine rectum anus Figure 1 The human digestive system

The processes that are involved in the movement of food through the digestive system • The following processes take place during digestion in humans: • Ingestion: the intake of food through the mouth • Digestion: the mechanical and chemical breakdown of food • Absorption: the diffusion of simple food molecules through the intestinal wall into the blood • Assimilation: the incorporation of nutrients such as amino acids and glucose into the cells • Egestion/defecation: the removal of undigested and unabsorbed waste from the body through the anus in the form of faeces. • Mechanical digestion is the process of breaking down food using the teeth to break up and chew the food. • Chemical digestion is the process by which the different nutrients in food are broken down to their constituent parts by enzymes. • The small intestine is the part of the alimentary canal where most digested food is absorbed. • Assimilation is the process of digestion in which glucose and amino acids are incorporated into cells. • The liver is important in assimilation because it is here that amino acids are deaminated. The liver is also important in glucose metabolism and the breakdown of alcohol, some drugs and hormones. Homeostatic control • The pancreas responds to the amount of glucose in the blood. When the blood glucose level is high, the pancreas secretes insulin. Insulin stimulates the liver to convert the excess glucose into glycogen and store it. This lowers the glucose level in the blood, and returns it to normal. When the blood glucose level is too low, the pancreas secretes the hormone glucagon. This stimulates the liver to convert the stored glycogen into glucose, which is then absorbed into the blood, raising the glucose level in the blood and returning it to normal. • Diabetes is a hormonal (endocrine) condition in which the body is either not producing insulin (type 1 diabetes) or cannot respond to the insulin that is being produced (type 2 diabetes). Insulin secreted by Islets of Langerhans converts excess glucose into glycogen for storage in the liver and muscles stimulates the cells to absorb glucose glucose level increases glucose level decreases normal glucose level in the blood glucose level decreases glucose level increases Glucagon secreted by Islets of Langerhans converts glycogen to glucose to be released into the blood Figure 2 The regulation of glucose in the blood

The relationship between food intake and health • Ingested food is the source of energy and nutrients for humans (and all mammals). • A balanced diet is one that contains all the food groups – proteins, fats and carbohydrates – in the correct proportions. • Different religious groups have different dietary laws. For example, Muslims and Jews do not eat pork and Hindus do not eat meat. • Dietary supplements are useful only to people who have genuine dietary deficiencies. • Malnutrition is either under-nutrition or over-nutrition. Kwashiorkor is an example of a nutritional disease caused by under-nutrition – a lack of protein and energy in the diet. • Tooth decay is caused by a build-up of plaque in the mouth, which is common with diets high in carbohydrates. Table 1 A summary of nutritional disorders Under-nutrition Condition Cause Symptom Kwashiorkor High intake of carbohydrate but Swollen belly; stick-like arms and insufficient protein (seen mainly in legs, sores on skin, swollen face and children) poor brain development Marasmus Lack of foods of all groups – energy Wizened face with deep- deficiency set eyes and tight skin, poor muscle development, little or no subcutaneous fat Anorexia Refusal to eat because of an Skeletally thin – may die if continues abnormal body image and fear of to refuse food becoming overweight Bulimia Food available and often well- May have normal body weight; nourished but habitual vomiting chronic bulimia causes tooth erosion after meals, often after binging on because of constant vomiting of high-energy foods acidic stomach contents Over-nutrition Condition Cause Symptom Obesity Excess intake of high-energy foods, Person’s body weight is more than usually carbohydrates 20% higher than the average person of the same sex and height Alcohol and drug abuse • Alcohol and other drugs of abuse cause serious damage to the body and are generally addictive.

UNIT 3: Cellular respiration brewing bread making production of lactic acid in role of anaerobic muscles during exercise respiration in industry products glycolysis, Krebs cycle, oxidative phosphorylation raw relative materials amounts in mitochondrion required of energy Anaerobic respiration released Aerobic respiration Comparison of aerobic and anaerobic respiration in cytoplasm Cellular respiration

UNIT 3 Cellular respiration • Cellular respiration takes place in all plant and animal cells and is the process by which energy is made available to cells. • Cellular respiration involves a series of chemical reactions within the cells. The chemical reactions trap or capture energy in molecules of adenosine triphosphate (ATP). • This process may be shown by the following word equation: enzymes Glucose + oxygen → carbon dioxide + water + energy (heat and ATP) Aerobic respiration • Aerobic respiration consists of three stages when oxygen is available. These stages are: • glycolysis • Krebs cycle • oxidative phosphorylation. • Glycolysis takes place in the cytoplasm of the cell, that is, outside the mitochondrion. This process does not need oxygen. • During glycolysis the fuel/glucose molecule is activated (phosphorylated). This activated glucose molecule undergoes a series of enzyme-controlled steps to form two molecules of pyruvic acid. In the process energy is released to form ATP. • The pyruvic acid can then enter into aerobic reactions or anaerobic (fermentation) reactions depending on: • whether oxygen is present or not • the needs of the cell • the type of cell. • Most aerobic respiration takes place in the mitochondria of the cells. • Most organisms use aerobic respiration and so are dependent on oxygen. Aerobic respiration and anaerobic respiration • Aerobic respiration involves the processes of glycolysis, the Krebs cycle and oxidative phosphorylation. • Anaerobic respiration is respiration in the absence of oxygen. It involves an additional process in glycolysis in which pyruvate is converted to carbon dioxide and alcohol in plants and to lactic acid in animals.

TWO MOLECULES OF PYRUVIC ACID In the presence of O2 In the absence of O2 mitochondria animals fermentation yeast and plant cells Krebs cycle electron transport system lactic acid alcohol + CO2 oxidative lactic acid alcoholic phosphorylation fermentation fermentation Aerobic and anaerobic reactions The role of anaerobic respiration in industry • Anaerobic respiration is also called fermentation. The process of fermentation is important in brewing and bread making. • Aerobic respiration produces large quantities of energy and anaerobic respiration produces small quantities of energy.

UNIT 4: Gas exchange insect bony fish trachea epiglottis bronchi earthworm mammal bronchioles dicotyledonous plants requirements lungs in different environments protected structure, location, ribs transport adaptations and system functioning of the well ventilated ventilation system intercostal muscles moist diaphragm Requirements Human gas of efficient gas exchange thin exchange organs alveoli lung surface area Homeostatic control of breathing Differences between Gas exchange respiration, breathing and gas exchange asthma Other Diseases and hay fever abnormalities bronchitis effects of altitude on artificial effects of gas exchange respiration smoking on lung cancer emphysema gas exchange

UNIT 4 Gas exchange Cellular respiration, breathing and gas exchange • Cellular respiration is a chemical process, which takes place within cells. During this process oxygen is used to break down food (fuel) molecules to release energy. • Breathing or ventilation is the mechanical process of taking oxygen into the lungs and releasing carbon dioxide from the lungs. • Gas exchange is a physical process, which takes place by means of diffusion and involves the exchange of gases between the air and the blood in the lungs and between the blood and other tissues of the body. • An efficient gas exchange organ requires a large surface area, it needs to be thin, it must be moist, it must be well ventilated and protected, and there may be a transport system associated with it. • Gas exchange organs differ according to lifestyle and habitat in different plants and animals. Human gas exchange • In humans and other mammals the gas exchange system is part of a complex respiratory system that is made up of large and small airways and is associated with a transport system. • The main organs of respiration in mammals are the lungs, which contain bronchi, bronchioles and alveoli. • Gas exchange takes place in the alveoli and the gases are transported around the body in the circulatory system. turbinate bones in nasal cavity nostril hard palate soft palate pharynx buccal cavity epiglottis vocal chords oesophagus larynx cartilage supporting trachea trachea (windpipe) Figure 1 The upper part of the respiratory system in humans

larynx trachea external intercostal ring of cartlage muscle supporting trachea internal intercostal muscle left lung pleural membrane left bronchus heart pleural fluid bronchiole diaphragm cut end of rib alveoli (air sacs) Figure 2 The lungs The mechanism of breathing or ventilation • The mechanism of breathing or ventilation of the lungs involves two processes, namely inhalation/inspiration and exhalation/expiration. This mechanism involves the action of different muscles, and the changes in the volume and pressure within the thoracic cavity. • During inhalation the muscles of the diaphragm contract and it becomes flattened. This results in an increase in the volume of the thoracic cavity from top to bottom (see Figure 3). • The external intercostal muscles contract while the internal intercostal muscles relax, and the rib cage is lifted. This increases the volume of the thoracic cavity from side to side and from back to front, and the pressure on the lungs (inter-pleural pressure) decreases. Atmospheric pressure is now greater than the pressure on the lungs. Air is therefore drawn through the nasal passages. Inhalation Exhalation trachea rib cage is raised rib cage drops down volume of thorax volume of thorax increases, so air decreases, forcing air is drawn into the out of the lungs lungs diaphragm moves up diaphragm is pulled down Figure 3 The mechanism of breathing or ventilation

Gas exchange in the lungs alveolus squamous epithelium CO2 O2 red blood corpuscles Figure 4 Longitudinal section through an alveolus and its capillary • During inhalation, the alveolus has a high concentration of oxygen and a low concentration of carbon dioxide. The blood capillaries around the alveolus, on the other hand, have a low oxygen concentration and a high carbon dioxide concentration. branch of air in branch of pulmonary artery pulmonary vein from pulmonary artery carbon dioxide out to pulmonary vein bronchiole alveolus wall with mucus layer alveoli (cut open) deoxygenated blood oxygenated blood alveoli alveoli (with capillaries) (with capillaries removed) carbon dioxide oxygen (mainly from plasma) (into red corpuscles) film of water alveolus wall capillary wall plasma red blood corpuscle Figure 5 Structure of alveoli, showing how gases pass in and out of capillaries • Oxygen dissolves in the moisture in wall of the alveolus. The gas diffuses into the blood capillary through the thin layers of epithelium that make up the alveolus wall and the single layer of endothelium that makes up the capillary wall. The oxygen is picked up by haemoglobin and transported by the blood. The carbon dioxide from the blood capillary diffuses in the opposite direction into the alveolus.

Gas exchange in the tissues • Blood arriving at the tissues via the arteries has a high concentration of oxygen in the form of oxyhaemoglobin and a low carbon dioxide concentration. The cells of the tissues have a low oxygen concentration and a high carbon dioxide concentration. • The oxyhaemoglobin splits (dissociates) into oxygen and haemoglobin. The oxygen diffuses through the capillary walls into the tissue fluid and then into the cells. The carbon dioxide diffuses from the cells into the tissue fluid and into the blood capillaries. Respiring tissue dissolved O2 gas dissolved CO2 gas Capillary blood Figure 6 The exchange of carbon dioxide and oxygen in the tissues The homeostatic control of breathing • Breathing is homeostatically controlled by sensory cells in the carotid arteries, which relay impulses to the medulla oblongata in the brain to increase or decrease the respiratory rate according to the concentration of carbon dioxide in the blood. After strenuous physical activity the carbon dioxide level in the blood increases rapidly due to the high rate of respiration. The sensory cells in the carotid arteries are stimulated by the high carbon dioxide concentration. Impulses from here are relayed to the medulla oblongata in the brain. The heart beats faster and The intercostal muscles and The abdominal muscles CO2 is therefore carried at a muscles of the diaphragm contract and force faster rate work harder, causing an the diaphragm up, assisting from the tissues to the lungs. increase in the breathing rate. in the emptying of CO2. Figure 7 The response of the respiratory system to exercise Diseases and abnormalities related to gas exchange in humans • Some diseases of the respiratory system are tuberculosis, asthma, bronchitis, emphysema and lung cancer. Hay fever also causes respiratory symptoms. Effects of altitude on gaseous exchange • Altitude affects gas exchange because of the lower concentrations of oxygen in the air. This affects athletes’ performance if they have not trained at altitude.

UNIT 4: Excretion in humans removal of urea reabsorption and excess water of glucose and and salts some salts urethra bladder ultra-filtration reabsorption kidney urinary system tubular excretion ADH nephron ureters Structure and pH control kidneys functions of: Homeostatic formation of urine control of water and salts substances excreted Excretion in aldosterone by each and origins of these substances humans kidney stones skin Excretion in various organs Diseases affecting lungs kidney function alimentary canal (gut) liver kidney and bilharzia kidney failure bladder due to overuse of some painkillers

UNIT 4 Excretion in humans Excretion • Excretion is the removal of the waste products of metabolism from the body. • People produce four main excretory substances: CO2, water, bile pigments, and urea and other nitrogenous waste substances. • CO2 is a waste product of cellular respiration. CO2 is transported in the blood from all cells of the body to the alveoli of the lungs. It is then excreted in the air that is exhaled. • Water is produced by all cells of the body during cellular respiration and it is also consumed in our food and drinks. Excess water is excreted in urine and in sweat (through the skin). • Bile pigments are produced by the breakdown of haemoglobin (the protein making up red blood corpuscles). The breakdown of haemoglobin takes place in the liver and is excreted as bile pigments in faeces. • Urea is made in the liver from excess proteins that are consumed. It is transported in blood to the kidneys from where it is excreted in urine. The urinary system • The organs of excretion in humans are within the urinary system and are the kidneys, the ureters, the bladder and the urethra. • The kidney’s structure is suited to its function. The macro- and micro- anatomy of the kidney means that its tissues are intimately associated with the blood circulation, which passes through a series of filters. vena cava aorta renal artery kidney renal vein renal pelvis ureter bladder urethra Figure 1 The position of the kidneys and associated structures in the human body renal capsule renal papilla cortex renal artery renal vein medulla hilum renal pyramid pelvis ureter calyx Figure 2 The internal structure of the kidney

afferent arteriole efferent arteriole from renal artery Malpighian body distal convoluted tubule ascending proximal convoluted tubule limb collecting duct descending limb loop of Henle renal tubule Figure 3 The structure of a nephron (simplified) narrow, efferent arteriole wide, afferent arteriole from renal artery podocytes with slit pores glomerulus squamous epithelium Bowman’s (capillary network) capsular space capsule renal tubule Figure 4 The structure of a Malpighian body (simplified) wide afferent arteriole glomerular capillaries – blood under pressure Bowman’s capsule narrow efferent arteriole renal artery podocytes with slit pores glomerular filtration tubular re-absorption peritubular capillary tubular excretion or secretion renal tubule to renal vein urine → to collecting duct → pelvis → ureter → bladder → urethra Figure 5 How a nephron functions

high water potential (hypotonic solution) ascending limb of Henle distal convoluted tubule both permeable to water impermeable walls cortex prevent water moving out H2O collecting duct medulla hypertonic solution H 2O Na+ in medulla Na+ H 2O H2O - Na+ sodium ions pumped Cl out creating a low peritubular Cl- water potential H 2O H2O blood (hypertonic solution) in medulla water capillary moves into blood capillary loop of Henle concentrated urine Figure 6 The role of the loop of Henle in conserving water Excretion and homeostasis • The process of filtration removes wastes and conserves salt and water, so the kidney has a homeostatic function. • The kidney regulates the pH of the blood by regulating the concentration of hydrogen ions. • The hormone involved in salt and water regulation is antidiuretic hormone (ADH). • The hormone aldosterone, secreted by the adrenal cortex, is involved in the regulation of the salt balance of the blood. Kidney diseases • Dialysis and kidney transplants are used to treat chronic kidney failure. • Kidney stones, overuse of painkillers and bilharzia are examples of causes of kidney disease.