Gr .11 Life Sciences term 2 Remote learning workbook term 2[1]

LIFE SCIENCES GRADE 11 REMOTE LEARNING WORKBOOK 1

TERM 2 2

Week Topic Page 1 Revision gr.10: Basic cell structure with a focus on the chloroplast and leave structure 4 2 Photosynthesis: Process and importance of photosynthesis 15 3 Photosynthesis: Effects of variable amounts of light, carbon dioxide and temperature on the rate of photosynthesis 23 4 Photosynthesis: Improved crop yields in greenhouse systems, the role of ATP as energy-carrier. 28 5 Animal nutrition: Dentition for herbivorous, carnivorous and omnivorous lifestyles 33 6 Animal nutrition: Human nutrition (Organs, functions, ingestion, digestion) 39 7 Animal nutrition: Human nutrition (Absorption, assimilation and egestion) 50 8 Animal nutrition: Homeostatic control 57 9 Cellular respiration: Process of respiration 63 10 Cellular respiration: Scientific investigation: CO2 is produced by living organisms during respiration 67 3

WEEK 1: TOPIC: Revision SUB-TOPIC: Basic cell structure (Focus on chloroplast and leave structure) NOTES & EXAM TIPS Biological terminology Carbohydrate A large group of organic compounds found in cells, including glucose, sucrose, and starch. Chloroplast A plastid in green plant cells which contains chlorophyll and in which photosynthesis takes place. Cuticle A protective and waxy layer covering the epidermis of a plant Epidermal Transparent cells found in the outer layer of a plant organ. These cells cells do not contain chloroplasts. Guard cells Curved cells containing chloroplasts that surround a stoma. These cells open and close the stomata(pores) Glucose A simple sugar which is an important energy source in living organisms and is a component of many carbohydrates. Mitochondrion An organelle found in large numbers in most cells, in which the cellular respiration and energy production occur. Nucleus A dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material. Palisade A layer of tall, thin cells containing many chloroplasts found mesophyll under the upper epidermis of the leaf Parenchyma Photosynthesizing cells containing chloroplasts Phloem the vascular tissue in plants which conducts sugars and other metabolic products downwards from the leaves. Spongy the inner tissue (parenchyma) of a leaf, containing many mesophyll chloroplasts. These cells are loosely packed and have many air spaces between them Starch Stored carbohydrate found in plants Stoma(ta) Opening in the surface of leaves that allows gases to move in and out of the leaf Vacuole a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid. Vascular a strand of conducting vessels in the stem or leaves of a plant, bundle typically with phloem on the outside and xylem on the inside. 4

Vein a slender rib running through a leaf or bract, typically dividing or branching, and containing a vascular bundle. Xylem 1. the vascular tissue in plants which conducts water and dissolved nutrients upwards from the root and also provides support in the plants. The structure of a cell Cytoplasm The cytoplasm is the jelly-like substance that fills the cell. It consists of up to 90% water. It also contains dissolved nutrients and waste products. Its main function is to hold together the organelles which make up the cytoplasm. It also nourishes the cell by supplying it with salts and sugars and provides a medium for metabolic reactions to occur. Nucleus The nucleus is the largest organelle in the cell and contains all the cell’s genetic information in the form of DNA. The presence of a nucleus is the primary factor that distinguishes eukaryotes from prokaryotes. A nucleus has four main parts: 1. the double nuclear membrane – it encloses the nucleus and contains small pores to allow for the passage of substances in and out of the nucleus 5

2. the nucleoplasm – this is a jelly-like fluid within the nucleus 3. the nucleolus – a dark body suspended in the nucleoplasm which contains free nucleotide bases and produces ribosomes 4. the chromatin network – found in the nucleoplasm, contains the DNA which forms the chromosomes containing the genetic code of a person / organism Mitochondria A mitochondrion is a membrane bound organelle found in eukaryotic cells. This organelle generates the cell’s supply of chemical energy by releasing energy stored in molecules from food and using it to produce ATP (adenosine triphosphate). ATP is a special type of” energy carrying” molecule. Plastids Plastids are organelles found only in plants. There are three different types: 1. Leucoplasts: White plastids found in roots. 2. Chloroplasts: Green-coloured plastids found in plants and algae. 3. Chromoplasts: Contain red, orange, or yellow pigments and are common in ripening fruit, flowers, or autumn leaves. Chloroplast The chloroplast is a double-membraned organelle. Within the double membrane is a gel-like substance called stroma. Stroma contains enzymes for photosynthesis. Suspended in the stroma are stack- like structures called grana (singular = granum). Each granum is a stack of thylakoid discs. The chlorophyll molecules (green pigments) are found on the surface of the thylakoid discs. Chlorophyll absorbs energy from the sun in order for photosynthesis to take place in the chloroplasts. The grana are connected by lamellae (intergrana). The lamellae keep the stacks apart from each other. 6

Watch the following videos: Cell structure: https://www.youtube.com/watch?v=URUJD5NEXC8 Chloroplast structure: https://www.youtube.com/watch?v=c8wA_0pfBu8 Structure of a leaf The leaf is a collection of tissues which include: 1. The epidermis which covers the upper and lower surfaces. 2. The mesophyll inside the leaf which is rich in chloroplasts. 3. The veins contain the vascular tissue (where xylem and phloem are present). Epidermis Epidermal cells form the outer layer covering a leaf, separating internal tissues from the external environment. Guard cells forming stomata are found in the lower epidermis. Epidermis tissue has several functions:  protection against water loss via stomata and a waxy cuticle  regulation of gaseous exchange Mesophyll cells The mesophyll is located between the upper and lower layers of the leaf epidermis, and is mostly made up of parenchyma (ground tissue) or chlorenchyma tissue. The mesophyll is the primary location for photosynthesis and is divided 7

into two layers, the upper palisade layer and the spongy mesophyll layer.  The upper palisade layer lies beneath the upper epidermis and consists of vertically elongated cells that are tightly packed together to maximise the number of cells exposed to sunlight. In addition, these cells contain many chloroplasts, thus, maximising their photosynthetic ability.  Beneath the upper palisade layer is the spongy mesophyll. The cells in the spongy mesophyll are slightly rounder and less densely packed and have air spaces to allow for gaseous exchange. Vascular Tissue Vascular tissue is made up of the xylem and phloem vessels.  Xylem transports water and minerals to the leaf.  Phloem transports dissolved sucrose made in the leaf out of its site of synthesis to the rest of the leaf. Most leaves have a bundle sheath around the xylem and phloem, consisting of sclerenchyma or collenchyma, for extra support. Watch the following videos: Leaf structure: https://www.youtube.com/watch?v=HxoAAmFT5A4 https://www.youtube.com/watch?v=J7vgZI1COoE 8

ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS Activities 1. Complete the crossword puzzle on plant and animal cells. 9

2. Fill in the labels of the following diagrams and give each diagram a heading. A. B. 10

C. D. 11

EXAM QUESTIONS QUESTION 1(Questions taken from various sources) Various options are provided as possible answers to the following questions. Choose the correct answer and write only the letter (A to D) next to the question number (1.1 to 1.3) in your ANSWER BOOK, for example 1.4 D. 1.1 The basic unit of life is a… A zygote. B protoplasm. C nucleus. D cell. 1.2 Material used to store genetic information in a cell is the … A ribosome. B deoxyribonucleic acid. C endoplasmic reticulum. D centrioles. 1.3 The … are only found in animal cells. A cellulose cell wall B endoplasmic reticulum C centrioles D vacuole (3 x 2) (6) QUESTION 2 (Questions taken from various sources) Give the correct biological term for each of the following descriptions. Write only the term next to the question number (2.1 to 2.3) in your ANSWER BOOK. 2.1 Cell organelles that are the site of protein synthesis 2.2 Pigment found in green plants 2.3 Organelle that serves as a storage site for water and mineral salts (3) 12

QUESTION 3 (Questions taken from various sources) Indicate whether each of the statements in COLUMN I applies to A ONLY, B ONLY, BOTH A AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B, or none next to the question number (3.1 to 3.3) in the ANSWER BOOK. COLUMN I COLUMN II 3.1 Cells in the leaf that A Palisade parenchyma contain chloroplasts B Spongy parenchyma 3.2 Responsible for gaseous A Guard cells exchange in a leaf B Epidermal cells 3.3 ‘Powerhouse’ of the cell A Nucleus B Mitochondria (3 x 2) (6) QUESTION 4 (Grade 10 topic tests: Cell and mitosis) 4 Study the diagram of a cell shown below 4.1 Write down the LETTER only of the: (a) Nucleus (1) (b) Endoplasmic reticulum (1) (c) Vacuole (1) 13

(d) Mitochondrion (1) (e) Cytoplasm (1) (f) Part that contains cellulose (1) 4.2 Provide one observable reason as to why this cell cannot be from the root of a plant. (1) (7) QUESTION 5 (EC Grade 10 P1 Nov 2019) 5 The following diagrams represent different types of cells. 5.1 Identify the type of cells represented by diagrams I and II. (2) 5.2 Give the NUMBER and the NAME of the organelle which serves as a storage site for water and mineral salts. (2) 5.3 Provide labels for parts A, B and C. (3) 5.4 State whether part D is a permeable, impermeable or selectively permeable membrane. Give ONE reason for your answer. (3) 5.5 A plant cell in a photograph measures 15 mm across. If the actual size of the cell is 0,015 mm, what is the magnification in the photograph? Show all your workings (3) (13) 14

WEEK 2: TOPIC: Photosynthesis SUB-TOPIC: Process and importance of photosynthesis NOTES & EXAM TIPS All living organisms require energy to survive. This energy can either be obtained directly from the sun (plants) or from the food that is eaten (animals). DEFINITION OF PHOTOSYNTHESIS The term photosynthesis means light (photo) to manufacture (synthesise) energy in the form of (glucose) carbohydrate stored in plants in the form of starch and to release oxygen into the atmosphere. TERMINOLOGY radiant energy energy from the sun, needed by plants for photosynthesis chloroplast organelle in plants, site for photosynthesis chlorophyll green pigment needed for photosynthesis thylakoids membranous sacs of the chloroplast that contains chlorophyll grana stacks of thylakoids (membranous sacs) where light phase of photosynthesis takes place here stroma part of chloroplast dark phase occurs light phase stage in photosynthesis which depends on light to form oxygen dark phase stage in photosynthesis which does not require light but occurs during light and uses products of light phase to form glucose stomata pores on leaves for gaseous exchange 15

A SIMPLIFIED PRESENTATION OF PHOTOSYNTHESIS 16

PROCESS OF PHOTOSYNTHESIS TERMINOLOGY photolysis splitting of water molecules into oxygen and hydrogen atoms. photo = light, lysis = split phosphorylation formation of energy transporting molecules called ATP ATP adenosine triphosphate, energy carriers glucose carbohydrate formed during photosynthesis The process of photosynthesis occurs in the choloroplast in two phases:  LIGHT PHASE : phase where light is required  DARK PHASE : phase where no light is required but occurs when there is light Both the light and dark phase occur in the organelle called the chloroplast. LIGHT PHASE OF PHOTOSYNTHESIS (REQUIREMENTS AND PRODUCTS) The light phase of photosynthesis takes place in the grana of chloroplasts as follows: 1.The required radiant energy is absorbed by chlorophyll in the grana. 2. Water is absorbed into the grana of the chloroplast 17

3. Radiant energy causes the water (H2O) molecule to split (photolysis), into H+ and O2. This oxygen is released into the atmosphere via the stomata. 4. Energy rich hydrogen (H+) ions formed during photolysis are carried by NADP ( H- carrier) to form NADPH . 5. Radiant energy causes the energy carrier ATP to be formed by phosphorylation. 6. NADPH + ATP formed during light phase will be used in the dark phase DARK PHASE OF PHOTOSYNTHESIS The dark phase of photosynthesis takes place in the stroma of chloroplasts as follows: 1. Carbon dioxide (CO2) enters leaves via stomata from the atmosphere 2. Carbon dioxide(CO2) and energy rich Hydrogen (H+ ) atoms, from the light phase, are combined using ATP, to from carbohydrates (glucose) 3. Excess glucose is stored as starch in starch granules in the stroma of chloroplasts. COMPARISON BETWEEN THE PHASES OF PHOTOSYNTHESIS LIGHT PHASE DARK PHASE Occurs in the grana Occurs in the stroma Light is required Light is not required 18

Radiant energy and water are absorbed Carbon dioxide is absorbed from the and used for the reactions of photolysis atmosphere & phosphorylation Photolysis occurs hydrogen and oxygen Hydrogen and carbon dioxide combine formed by splitting by using ATP to form glucose. Glucose H2O.Phosphorylation occurs: ATP is is formed and excess is stored as starch produced and oxygen is released to the atmosphere THE IMPORTANCE OF PHOTOSYNTHESIS Photosynthesis is important for the following reasons: 1. It supplies energy to almost all living organisms. Plants are the only organisms that can convert the sun’s energy into organic compounds. 2. Plants convert the simple sugars made during photosynthesis into more complex organic compounds such as starch, fats, proteins and vitamins which form food source for all living organisms. 3. Photosynthesis regulates the concentrations of carbon dioxide, and oxygen in the atmosphere, and plays a key role in the carbon cycle in preventing global warming. 4. Plants absorb more carbon dioxide during photosynthesis than they release during cellular respiration. 5. Organisms require the oxygen released during photosynthesis for cellular respiration to provide energy to all cells and organs. 19

ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 Various options are provided as possible answers to the following questions. Choose the correct answer and write only the letter (A to D) next to the question number (1.1 to 1.3) in your ANSWER BOOK, for example 1.4 D. 1.1. Plants use oxygen… A continuously. B during the day only. C during the night only. D during photosynthesis only 1.2. Test tubes A and B below were placed in bright light. Which of the following is correct regarding the test tubes? A The amount of CO2 in test tube A will decrease. B The amount of CO2 in test tube B will increase. C The amount of O2 in test tube B will increase. D The amount of O2 in test tube A will increase. 1.3. What are the products of the light reactions of photosynthesis that are used in the light independent phase? A CO2 and glucose B ATP and H+ C H2O and O2 D ADP and CO2 (3x2=6) 20

QUESTION 2 Give the correct biological term for each of the following descriptions. Write only the term next to the question number (2.1 to 2.3) in your ANSWER BOOK. 2.1 The green, light-trapping pigment in photosynthesis found in plant leaves. 2.2 The splitting of water molecules into hydrogen and oxygen in the presence of light 2.3 Site of reactions of the light - independent phase in the chloroplast. (3x1=3) QUESTION 3 (Questions taken from various sources) Indicate whether each of the statements in COLUMN I applies to A ONLY, B ONLY, BOTH A AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B, or none next to the question number (3.1 to 3.3) in the ANSWER BOOK. COLUMN I COLUMN II 3.1 Molecule that stores energy A ATP B ADP 3.2 Storage of chlorophyll A Grana B Lamella 3.3 Hydrogen carrier in light phase A NAD B NADP (3 x 2) (6) QUESTION 4 21

4.1. Identify the phases labelled as Phase 1 and Phase 2 (2) 4.2. Provide the two raw materials labelled as A and B. (2) 4.3. Name the by-product labelled as C. (1) 4.4. Which substance labelled as D is essential for Phase 2? (1) 4.5. Name the product E that is produced during Phase 2. (1) 4.6. In what form is E stored in plants? (1) (8) 22

WEEK 3: TOPIC: Photosynthesis SUB-TOPIC: Effects of variable amounts of light, carbon dioxide and temperature on the rate of photosynthesis NOTES & EXAM TIPS The rate or speed at which photosynthesis takes place depends on the following three factors:  Light intensity  Concentration of carbon dioxide (CO2)  Temperature The graphs below show how different factors affect the rate of photosynthesis 1. Light intensity  When light intensity increases, the rate of photosynthesis also increases to an optimum level. If light intensity continues to increase, there will be no effect on the rate of photosynthesis.  When light intensity decreases, the rate of photosynthesis also deceases.  When the light intensity is low, the rate of photosynthesis is low. 23

2. Concentration of carbon dioxide  As the carbon dioxide concentration level increases, the rate of photosynthesis increases.  If the carbon dioxide concentration is higher than the optimum amount, photosynthesis will remain constant.  When carbon dioxide concentration is low, the rate of photosynthesis is low.  Light independent phase cannot take place more quickly than what it does at the optimum level of carbon dioxide concentration. 3. Temperature  When temperature is low, the rate of photosynthesis is low.  As temperature increases, the rate of photosynthesis also increases.  When temperature is at the optimum amount, the rate of photosynthesis will reach a maximum. 24

 If the temperature is higher than the optimum amount, rate of photosynthesis will decrease.  The enzymes used in the process will denature at high temperatures and will no longer function. ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 Scientists set up an apparatus to investigate the effect of temperature, light intensity and carbon dioxide concentrations on plant growth. Using this apparatus, they could control each factor.  The scientists set different temperatures, CO2 concentrations and light intensity for four different groups of lettuce plants.  The average mass of lettuce plants serves as an indication of the rate of photosynthesis. Study the results below and answer the questions that follow. 1.1 What is the influence of light intensity on average mass of lettuce plants? (3) 1.2 Name two limiting factors that influence the rate of photosynthesis as the light 25

intensity increases? (2) 1.3 How were the scientists able to increase the rate of photosynthesis to the maximum level? (3) 1.4 What would happen to the rate of photosynthesis if the temperature is raised beyond 35°C? (1) 1.5 Give a reason for your answer in QUESTION 1.4. (1) (10) QUESTION 2 The diagram below shows the apparatus that was used to investigate the rate of photosynthesis in a submerged plant. The light intensity to which the plant is subjected was decreased at a regular interval by moving the light source away from the plant. The average number of bubbles minute was counted and recorded for each distance. The results were recorded in a table: Distance of lamp Number of bubbles from the plant (cm) per minute 10 60 20 60 30 60 40 60 50 55 60 50 70 45 80 40 90 35 100 30 2.1 What is the aim of the investigation? (1) 2.2 Name the gas released by the plant. (1) 26

2.3 Describe a test to verify your answer in QUESTION 2.2. (2) 2.4 Describe the relationship between the gas released and light intensity. (2) 2.5 Name TWO other environmental factors, except light intensity which you think could change the rate of bubbles production. (2) 2.6 Draw a graph representing the results in the table above. (6) (14) 27

WEEK 4: TOPIC: Photosynthesis SUB-TOPIC: Improved crop yields in greenhouse systems, the role of ATP as energy-carrier NOTES & EXAM TIPS How does a greenhouse work? A greenhouse can help increase plant growth and fruit production and even allow you to grow plants that wouldn't normally survive in your climate. Step 1: Light Comes In In order to provide light, greenhouses need to have some way for the light to come in. This is why greenhouses are made of mostly translucent materials, like glass or clear plastic. This gives the plants inside maximum access to sunlight. Step 2: Heat Is Absorbed When the light comes in the glass walls of the greenhouse, it is absorbed by the plants, ground and anything else in the greenhouse, converting it to infrared energy (heat) in the process. The darker the surface, the more energy it can absorb and turn into heat. Step 3: Heat Gets Trapped Once the light energy gets converted into infrared energy (heat), it has a different "shape" than light energy - what scientists refer to as wavelength. The change in the wavelength makes it so that the heat can't easily escape out of the greenhouse's glass walls. So while getting in was easy, getting out is harder. Step 4: Warming the Greenhouse The trapped heat warms the air inside the greenhouse and because a greenhouse is relatively air-tight, the warmer air stays inside, raising the entire building's temperature. Step 5: Staying Warm With sufficient sunlight, the temperature inside a greenhouse may become much higher than the outdoor temperature; in fact, on a hot sunny day you may need to ventilate the greenhouse all day to keep from literally cooking the plants inside. On overcast days, less sunlight means that the greenhouse will heat up more slowly, if at all. For that reason, greenhouses are most useful in areas that have plenty of sun. Step 6: Promoting Photosynthesis All this light and warm temperatures give plants ample access to the sunlight and temperatures need to grow. This is because they have the right conditions for photosynthesis to occur. On average, plants need about six hours of sunlight per 28

day, although this varies depending on the type of plant; placing your greenhouse where it will get full sun all day will ensure that the plants inside get enough light. ATP as energy carrier in cells:  ATP stands for adenosine triphosphate (Energy carrier)  When a cell needs energy, ATP is broken down and the energy is released. Cells use this energy to produce important molecules such as proteins, fats etc.  During photosynthesis the energy from ATP is used in the reaction that make energy-rich glucose from the raw material CO2 and H2O. When this happens, ATP loses a phosphate and ADP (adenosine diphosphate) is formed. Radiant energy from sunlight can then be used to change the less active ADP back to high energy ATP so that there is more energy available to do more work. Investigation: Light is required for photosynthesis Light is one of the requirements for photosynthesis. An investigation can be performed to show that without light, starch will not be produced and therefore no photosynthesis took place. Hypothesis: Light is needed for photosynthesis. Aim: To prove that light is required for photosynthesis 29

Materials/apparatus destarched plant alcohol water bath test tube tripod & gauze iodine solution white spotting tile tweezers test tube holder, tinfoil Method: 1. Destarch a potted plant by placing it in a dark cupboard for 48 hours 2. Cover a portion of the leaf, still attached to the plant, with aluminium foil with a pattern cut out. 3. Place the plant in a sunny area for 48 hours 4. Pick the leaf and remove the foil 5. Test for the presence of starch using the starch test. The experiment is the part of the leaf covered by the foil, as it does not receive light. The part of the leaf left uncovered is the control as it receives all of the requirements for photosynthesis, including light. Results: Experiment (leaf covered with tinfoil): The parts of the leaf covered with foil remains light brown and the S-shape turns blue-black. Control (leaf left uncovered): The complete leaf turns blue-black. Conclusion: The parts that turn blue-black in colour contain starch. The part which remains light brown does not contain starch. Light is essential for photosynthesis to take place. 30

Watch the video: Investigating the effect of light intensity on the rate of photosynthesis: https://www.youtube.com/watch?v=id0aO_OdFwA Starch Test Procedure 1. Bring water bath to boil. 2. Put leaf to be tested in the boiling water for about 30 seconds. (This softens and kills the leaf) 3. Remove the leaf from the water and place in tube of alcohol. 4. Put the tube back into the beaker of hot water. (The alcohol will remove the chlorophyll). 5. When the leaf is white, (about ten minutes) remove the leaf from the alcohol and place it once again in the hot water for a few seconds. (The leaf will be brittle when you take it out of the alcohol and the hot water softens it). 6. Place the leaf on the spotting tile and cover it with iodine. Leave for a minute or two. 7. The presence of a blue/black colour indicates the presence of starch. SAFETY PRECAUTIONS 1. Make sure that there is no naked flame lighting anywhere near the alcohol. It is particularly important if using a bunsen for the water bath that the bunsen is turned off before putting the alcohol into the bath. 2. Do not pour the alcohol down the sink. ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 The following table diagrams represent investigations involved in a process which takes place in green plants. The plant/leaves represented as A and C were exposed to sunlight for 4-5 hours. 31

1.1 Which investigation (A, B or C) is designed to test the following? a) Chlorophyll is necessary for photosynthesis b) Light is required for photosynthesis c) Oxygen is produced during photosynthesis 1.2 Give the letter of the investigation that does not show a control. 1.3 Which investigation(s) needs a chemical to test for whether photosynthesis took place? QUESTION 2 A tomato farmer was able to produce crops in greenhouse which were heated to between 15oC and 22oC. in addition, the carbon dioxide level was increased from the normal 0,03% to 0,1%. 2.1 State ONE way in which the farmer could have enriched the air inside the greenhouse with CO2, without burning any fuel. 2.2 Explain how increasing the CO2 levels up to 0,1% can lead to an increased production of tomatoes. 2.3 Name TWO other factors which might have to be increased to obtain an even greater yield when the CO2 level is increased to above 0,1%. 2.4 The additional CO2 is only provided during the daylight hours. Suggest a reason for this. 2.5 Predict what would happen if the CO2 concentration within the greenhouse is increased to 0,5% for between 10 to 15 days if all other factors are kept constant. 32

WEEK 5: TOPIC: Animal nutrition SUB-TOPIC: Dentition for herbivorous, carnivorous and omnivorous lifestyles. NOTES & EXAM TIPS Mammalian animals have teeth that are adapted to eating certain types of food . There are four types of teeth, although not all mammals have all types. In the front of the mouth are incisors, teeth that function in chiseling or nipping. On each side of the incisors may be found the canines, useful in biting and piercing prey. Behind the canines are "cheek teeth": the premolars, that do some grinding, and the molars, that do most of the grinding and chewing. Muscles in the jaws are designed to put a great deal of force behind this motion. The size and shapes of these tooth types are correlated with the different diets of mammalian species. Herbivores (herbi, plant; vore, eater) are animals that consume plant material.  Cow, deer, horse, giraffe, squirrel, and butterfly are examples of herbivores. Carnivores (carni, meat; vore, eater) are meat eating animals that have to hunt and kill their prey to eat.  Lion, tiger, jackal, vulture, owl, eagle, snake, and spider are examples of carnivores. Omnivores (omni, all; vore, eater) are adapted to eating both plant and animal tissue.  Bear, raccoon, crow, and human beings are examples of omnivores. 33

Teeth of herbivores, carnivores and omnivores Types of teeth Skulls of herbivores, carnivores and omnivores 34

Different teeth = Different diets ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 Various options are provided as possible answers to the following questions. Choose the correct answer and write only the letter (A to D) next to the question number (1.1 and 1.2) in your ANSWER BOOK, for example 1.3. C. 1.1 What type of teeth are 1 and 2 in the following diagram? A Incisor 35

B Canine C Molar D Premolar 1.2 Of the four types of teeth found in mammals, which type is used for tearing and holding on to the prey? A Canines B Premolars C Molars D Incisors QUESTION 2 Give the correct biological term for each of the following descriptions. Write only the term next to the question number (2.1 to 2.2) in your ANSWER BOOK. 2.1 The group of animals that feed only on plant material. 2.2 Flat and uneven teeth used for grinding and crushing food. QUESTION 3 Complete the table below: Herbivore Carnivore Omnivore Type of food Facial muscles (Complexed/Reduced) Example QUESTION 4 The following table compares the dental formulae of three animals: a horse, leopard and man. Study it and answer the questions that follow. 36

Animal I C P M A 𝟐 𝟏 𝟐 𝟑 𝟐 𝟏 𝟐 𝟑 B 𝟑 𝟏 𝟒 𝟑 𝟑 𝟏 𝟒 𝟑 C 𝟑 𝟏 𝟑 𝟏 𝟑 𝟏 𝟑 𝟏 4.1 State which animal (horse, leopard and man) is represented by A, B and C. 4.2 Explain each of your answers to QUESTION 4.1. 4.3 Calculate the total number of teeth that each animal has. QUESTION 5 Complete the crossword puzzle below. 1 2 3 4 5 6 7 8 9 37

Across Down 5. animals which hunt other animals 1. animals that eat plants only 8. animal that eats plants and animals 2. warm bloodied animals with hair 9. sharp curved nails on animal foot 3. front teeth 4. animal that eat other animals only 6. back teeth 7. animal that is hunted and eaten 38

WEEK 6: TOPIC: Animal nutrition SUB-TOPIC: Human nutrition (Organs, functions, ingestion, digestion). NOTES & EXAM TIPS The digestive system The digestive system is made up of the alimentary canal and associated organs. The alimentary canal is made up of the mouth, pharynx, oesophagus, stomach, small intestines, and large intestines. Accessory organs are organs that aid in the alimentary canal to perform its digestive function. These include the tongue, teeth, salivary glands, pancreas, liver, and gall bladder. The digestive system 39

The alimentary canal 1. The mouth cavity, salivary glands, teeth, and tongue The mouth cavity consists of two lips in the front, a tongue, and teeth as the floor of the mouth and teeth and palate as the roof of the mouth. The mouth is made up of stratified epithelium connective tissue that also has salivary glands that produce saliva. The tongue is a movable muscular organ that pushes the food between the teeth for mastication, assist in mixing food with saliva, forming food into a bolus and swallowing food. It also contains taste buds and serve as the organ of taste. The salivary glands are found in the muscles around the mouth. Salivary glands are referred to as exocrine glands since it transports secretions by means of ducts. Salivary amylase or carbohydrase are released from the salivary glands to hydrolyse carbohydrates during chemical digestion. The teeth are embedded in the upper and lower jaws. There are four types of teeth 2.1.2.3 namely incisors, canines, premolars, and molars. The human dental formula is 2.1.2.3 that is half of the upper jaw. This means that the human mouth has 2 incisors, 1 canine, 2 premolar and 3 molars in one half in the upper jaw. These values are multiplied by 4 to get the total number of teeth in the human. Types of human teeth Type of teeth Description Function Total in the human mouth Incisors Shaped like Used for biting off 8 incisors chisels pieces of food Canine Conical in shape Assist incisors in 4 canines tearing off food Premolars Flat surfaces with Grinding the food 8 premolars two pointed cusps Molars Large flat surface Grinding and 12 molars with three to five crushing the food cusps 40

2. The Pharynx The area at the back of the mouth cavity that passage into oesophagus. The opening to the trachea is closed during swallowing by a leaf shaped cartilage called the epiglottis. This prevents a person from choking on food. 3. The oesophagus The narrow tube that run from the pharynx to the stomach. 4. The stomach The stomach is a bag-like organ in the abdominal cavity below the diaphragm. The cardiac sphincter prevent food from pushing from the stomach back into the oesophagus. When food leave the stomach, it enters the duodenum (small intestine), and a pyloric sphincter prevents food from pushing back into the stomach. 5. The small intestines The small intestines are divided into three parts. The duodenum, jejunum, and ileum. The duodenum receives bile salts and enzyme lipase for the digestion of lipids. The jejunum is a mid-size tube that leads to the ileum which is the longest part of the small intestine. The small intestine contains four layers that helps with the digestion process. The four layers of the small intestine. (http:// criticalcaredvm.com) Layer 1: the serosa is on the outside of the small intestine. Layer 2: the muscular layer that consists of longitudinal and circular muscles. Layer 3: the submucosa made up of connective tissue with blood vessels, lymph, and nerves. 41

Layer 4: the mucosa that is the most inner layer with columnar epithelium that secrete mucous. The mucosa contains millions of finger-like projections called villi that plays a role in absorption. The villi 6. The large intestines The large intestines consist of three parts namely the caecum, colon, and rectum. The caecum is the sac-like portion which opens from the small intestine, the colon that leads to the rectum, and the rectum that opens into the anus. The appendix is attached to the caecum. Accessory organs 1. The liver and gall bladder The liver is a large organ lying just below the diaphragm partially covered by the stomach. The liver consists of two lobes which has two ducts known as the hepatic and cystic duct. The hepatic duct arises from the liver cells and the cystic duct arise from the gall bladder. Main functions of the liver are to act as storage place for glycogen and minerals such as iron. Secondly the liver deaminate excess amino acids which forms urea that is excreted by the kidneys and lastly to detoxify harmful substances such as drugs and alcohol. The call bladder secretes a yellow green alkaline liquid that has no enzymes that is responsible for the emulsification of fat. Emulsification of fat refers to the break-up of fats into droplets to increase the enzyme action of lipase to digest lipids. 42

2. The pancreas The pancreas is a large gland which lies in the loop of the duodenum that secretes pancreatic juice from the islets of Langerhans. These specialized cells secrete the hormone insulin and glucagon responsible for controlling the blood sugar level. Pancreatic juice contains enzymes that helps in the digestion of lipids. Processes of the digestive system The digestive system consists of four processes: 1. Ingestion 2. Digestion 3. Absorption and assimilation 4. Egestion Ingestion Ingestion is the process of taking in food through the mouth cavity. Pieces of food are bitten off by the teeth before mechanical digestion takes over digestion. Refer to the above descriptions of each organ for functions. Digestion Food is digested by means of chemical and mechanical digestion. Mechanical digestion refers to the breakdown of food by the action of muscles whereby chemical digestion involves the chemical breakdown of food by means of chemicals such as enzymes. The enzymes that help with the breakdown of food includes: 43

Group of enzymes Carbohydrase Protease Lipase Saliva, Stomach, Where they are Pancreatic juices, pancreatic juices, pancreatic juices produced intestinal Juices intestinal juices intestinal juices Carbohydrates Lipids (fats and Substrate Proteins (starch) oils) Acidic in stomach, Preferred pH Slightly alkaline Alkaline in small Slightly alkaline intestine End product of Glycerol & fatty Glucose Amino acids digestion acids Other chemicals include pancreatic juice, gastric juice, and bile. Gastric juice contains the enzyme protease as well as hydrochloric acid that breaks down protein and acts as an antiseptic to kill germs taken in with the food. Pancreatic juice meets the bile in duodenum which contains sodium bicarbonate that neutralizes the acid food coming from stomach. Mechanical digestion includes mastication in the mouth and peristalses in the oesophagus, stomach, and the small intestines. Mastication breaks the food into a fine pulp which mix the food with saliva using the tongue. The tongue, and palate mould the food into a small bolus that helps during the swallowing process. The tongue moves back and up to close the glottis using the epiglottis to prevent the food from choking a person. Peristalsis is the rhythmical contraction of muscles of the alimentary canal causing the food to move along the gut. This action is involuntary. The circular muscles of the oesophagus wall above the bolus contracts which narrows the tube above the bolus. The circular muscles under the bolus relax and the oesophageal wall widens forcing the bolus downward. The stomach has muscles that allow the food through peristalsis to mix the food with gastric juices and pushing the food into the small intestine. 44

ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 Various options are provided as possible answers to the following questions. Choose the answer and write only the letter (A-D) NEXT TO THE QUESTION NUMBER 1.1-1.6 in your ANSWER BOOK, e.g. 1.7 D. 1.1 Which ONE of the following can be absorbed into the blood without further digestion? A Starch B Glycogen C Glucose D Fats 1.2 If the pancreatic duct is cut. A Protein digestion will not be affected B Homeostatic control of the glucose level will be affected C Carbohydrates digestion will be affected D Carbohydrates digestion will be affected 45

1.3 Which ONE of the following is not part of the alimentary canal? A Stomach B Colon C Pancreas D Appendix 1.4 Which ONE of the following combinations of temperature and pH values will give the best conditions for a protein digesting enzyme found in the stomach? A 25°C, pH 2 B 30°C, pH 5 C 37°C, pH 3 D 40°C, pH 7 1.5 Where does the emulsification of fat occur? In the … A Liver. B Colon. C Gallbladder. D Small intestine. 1.6 Study the accompanying diagram and answer Question 1.6 46

Which labeled structure secretes a hormone which causes an increased production of glycogen? A Z B Y C X D W (12) QUESTION 2 Give the correct biological term for each of the following descriptions. Write only the term next to the question number. 2.1 The muscular tube that connects the mouth cavity to the stomach. 2.2 The tiny finger-like projections in the small intestine 2.3 Substance secreted by the liver to emulsify fats 2.4 Ball of chewed food mixed with saliva formed in preparation for swallowing (4) QUESTION 3 Indicate whether each of the descriptions in Column I applies to A ONLY, B ONLY, BOTH A AND B, or NONE of the items in Column II. Write A only, B only, both A and B, or none next to the question number. Column A Column B 3.1 Substances that need to be A: amino acid digested before absorption B: glucose 3.2 The enzymes secreted by the A: proteases pancreas B: carbohydrates 3.43 The structure where chemical A: oesophagus digestion does not take place B: large intestine 3x2= (6) 47

QUESTION 4 Study the diagram below which shows the human digestive system 4.1 Label parts A, C, E and H respectively (4) 4.2 Write the letter of the part ….. (a) that stores bile (1) (b) where most enzymes are active to digest food (1) (c) where most water and mineral salts are absorbed (1) (7) QUESTION 5 In a shooting accident at the age of 19, Alexis St Martin’s left side of his abdomen was shot away. A medical doctor, Dr Beaumont was quickly on the scene but did not give Alexis 36 hours to live. Alexis however made a miraculous recovery but was left with a hole in his stomach. To prevent that food and juices pour out, he had to wear a bandage. 48

Dr Beaumont used this golden opportunity to study the digestion process in the stomach. He tied a string around a piece of meat and inserted it through the hole in Alexis’ stomach. At frequent intervals the meat was removed to find out how long it would take for the meat to be digested. In a series of experiments he used gastric juices from Alexis’ stomach. Different types of food was placed into test tubes and covered with Alexis’ gastric juice at 38oC. The digestion time of these nutrients were compared with the digestion time in the stomach. [www.livescience.com] The results are represented in the table below. Type of food Digestion time in the Digestion in the test stomach (min) tube (min) Raw eggs 120 255 Hard-boiled eggs 210 480 Milk 135 285 Steak 190 495 Cheese 210 5.1 Why were the test tubes kept at 38oC? (2) 5.2 Which organic nutrient is present in all the above food types? (1) 5.3 Give the name of the enzyme responsible for the digestion of this nutrient. (1) 5.4 Why does it take longer to digest a hard-boiled egg than a raw egg? (2) 5.5 Make use of a bar graph to show the digestion time of the different types of food in the stomach only. (6) (12) 49

WEEK 7: TOPIC: Animal nutrition SUB-TOPIC: Human nutrition (Absorption, assimilation and egestion). NOTES & EXAM TIPS ABSORPTION  Digested food is now in a soluble form and ready to be absorbed into the bloodstream.  Most absorption of digested food occurs in the small intestine.  The small intestine is structurally adapted for maximum absorption o The length of the small intestine ensures that food remains for long periods, allowing enough time for maximum absorption. o There are transverse folds and millions of villi in the mucosa of the wall of the small intestine, which increase the absorption surface considerably.  The soluble nutrients are mainly absorbed through the villi.  The villus is structurally adapted for efficient absorption of these nutrients: o The columnar epithelium surrounding the villus is only one cell layer thick for fast and easy diffusion. o The villus is richly supplied with capillaries for the absorption of glucose, amino acids, vitamins, mineral salts and water. o The villus has a central lacteal for the absorption of fats. o Goblet cells in the columnar epithelium secrete mucus which is the medium in which nutrients dissolve. o The columnar epithelium has many mitochondria which provide energy for active transport. o Microvilli on the columnar epithelium increase the absorption surface. 50

Intestinal villi Absorption process  The end products of digestion (glucose, amino acids, fatty acids and glycerol) as well as vitamins, mineral salts and water are absorbed by the villi in the small intestines. o Glucose, the end product of carbohydrate digestion, is actively absorbed, against the concentration gradient, into the blood capillaries of the villi. o Amino acids, the end products of protein digestion, are also actively absorbed, against the concentration gradient, into the blood capillaries. o Glycerol and fatty acids, the end products of lipid digestion, are absorbed by diffusion into the lacteals aided by bile salts. o Vitamins – fat soluble vitamins (A, D, E and K) are passively absorbed or aided by carrier molecules. o Mineral salts are both actively and passively absorbed into the capillaries. o Water is absorbed into the capillaries by osmosis. Large amounts of water, certain vitamins and mineral salts are also absorbed in the colon. Transport of absorbed nutrients  Glucose, amino acids, vitamins, mineral salts and water are absorbed through the blood capillaries in the villi.  The capillaries join to form larger veins that eventually open into the hepatic portal vein.  The hepatic portal vein transports the absorbed nutrients to the liver. 51

 In the liver: o most of the glucose is converted to glycogen and stored in this form. o excess amino acids undergo deamination to form urea and glucose.  The urea is transported to the kidneys where it is excreted as part of urine.  The remaining glucose and amino acids leave the liver via the hepatic veins and are transported in the inferior vena cava to the heart and to the rest of the body.  A large portion of glucose is transported to the tissues (especially muscle tissues), where it is broken down by cellular respiration to CO2 and water with the release of energy.  Fatty acids and glycerol are absorbed by the lacteals of the villi.  The lacteals unite and form larger lymphatic vessels that eventually open into the thoracic duct.  Fatty acids and glycerol in the thoracic duct enter the blood system at the left subclavian vein and are transported to the rest of the body via the heart. ASSIMILATION  The body cells absorb the required nutrients, necessary for the building compounds and cell structures, from the blood.  This process is known as assimilation. EGESTION  Large amounts of water are absorbed from the semi-solid waste in the colon, which reduces the liquidity of the content.  Undigested and indigestible waste (faeces) is stored temporarily in the rectum.  Muscle contractions of the rectum and relaxation of the circular muscle of the anus cause faeces to be expelled to the outside. The process is also known as defecation.  Roughage is indigestible substance found in plant material. These include cellulose, lignin and pectin.  Roughage is essential for the effective functioning of the digestive system in that it: o promotes peristalsis – decreases transit time o prevents constipation and haemorrhoids o softens faeces to facilitate defecation 52

Terminology Ingestion taking in food complex foods into the body by biting and chewing Digestion The breaking down of complex food into simpler substances using mechanical and chemical methods. Absorption Absorbing simple food substances into the blood. Assimilation Taking the simple food substances from the blood into the body cells. Egestion Excreting waste products from food products the body no longer need. Carbohydrates Main source of macronutrients such as sugars, starches, and fibres. Lipids Macronutrient made from 3 fatty acids and one glycerol providing energy to the body Protein Macronutrient made from amino acids important for building muscles. Alimentary Continuous tube that starts at the mouth and end at the anus that canal consists of different organs with different functions to aid in nutrition. Accessory Organs in the digestive system that does not form part of the organs alimentary canal but aid the alimentary canal with digestion. Enzyme A biological molecule (protein) that significantly speed up the rate of chemical reactions that take place within cells. They are vital for life and serve a wide range of important functions in the body. Protease Enzyme that hydrolyses protein into amino acids Lipases Enzyme that hydrolyses lipids into fatty acids and glycerol Carbohydrase Enzyme that hydrolyses carbohydrates into simple sugars such as / Salivary glucose amylase Peristalsis The contraction and relaxation of muscles in the oesophagus to aid in the movement of food to the stomach. 53

ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 Indicate whether each of the statements in COLUMN I applies to A ONLY, B ONLY, BOTH A AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B, or none next to the question number (1.1 to 1.5) in the ANSWER BOOK. COLUMN I COLUMN II 1.1 Elimination of undigested food, A Ingestion usually via defecation B Egestion 1.2 Absorption of nutrients by body A Assimilation cells for building compounds B Peristalsis 1.3 A lymph vessel in the villus of the A Lacteal small intestine B Lymphatic node 1.4 Transports absorbed nutrients to A Inferior vena cava the liver B Hepatic portal vein 1.5 Actively absorbed against the A Glucose concentration gradient into blood B Amino acids capillaries (5 x 2) (10) 54

QUESTION 2 Study the diagram below, which shows part of the human digestive system, and answer the question that follow 2.1 Identify parts B and E. (2) 2.2.2. Explain THREE structural adaptations of E for effective absorption. (6) 3 State THREE functions of roughage (fibre) in the digestive system. (3) (11) 55

QUESTION 3 The accompanying diagram represents a structure associated with the human digestive system. Study the diagram and answer the questions that follow. 3.1 Which structure is represented here? (1) 3.2 State the main function of the above structure. (1) 3.3 Explain TWO reasons why this structure is so efficient in its function. (4) 3.4 Name TWO substances which are found in higher concentration in C than in D. (2) 3.5 Label parts A and E. (2) 3.6 Briefly explain the function of structure B? (2) (12) 56

WEEK 8: TOPIC: Animal nutrition SUB-TOPIC: Human nutrition (Homeostatic control, which involves the hormonal control of blood sugar levels). NOTES & EXAM TIPS Terminology homeostasis the ability of an organism to maintain stability of internal conditions (e.g. temperature, chemical balance) despite changes in its environment negative mechanisms in the human body that detect changes or feedback imbalances in the internal conditions and restore homeostasis mechanisms blood glucose amount of glucose in the blood insulin a hormone made in the pancreas and released into the blood to help convert glucose to glycogen to reduce blood glucose glucagon a hormone made by the pancreas that raises blood glucose levels by converting stored glycogen to glucose glycogen form in which glucose is stored in the liver and cells. The following is a general sequence of events in a negative feedback mechanism: Step 1 An imbalance is detected Step 2 A control centre is stimulated Step 3 Control centre responds Step 4 Message is sent to target organ/s Step 5 The target organ responds Step 6 It opposes / reverses the imbalance Step 7 Balance is restored. Position of the pancreas in the body Pancreas: Islets of Langerhans Glucagon Stimulates conversion from glycogen to glucose (increases blood glucose level) Insulin Stimulates conversion of glucose to glycogen (reduces blood glucose level) 57

The following describes the regulation of blood glucose levels. Blood glucose refers to the amount of glucose in the blood. Glucose is absorbed into the blood from the digestive system. Glucose found in the blood is taken up by the body’s cells to be used for cellular respiration which releases energy. If blood glucose levels are too low, the body cells cannot release enough energy and the body cannot function at its best. If blood glucose levels are too high, water is drawn out of the cells and into the bloodstream. This results in dehydration of the cells and therefore dehydration of the body. The pancreas monitors the amount of glucose in the blood. After a meal, blood glucose levels will increase because more glucose is absorbed from the small intestine into the blood (Figure 9). The pancreas detects an increase in blood glucose and releases the hormone insulin which causes the glucose to be converted into glycogen. Glycogen is stored in the liver and skeletal muscles in the body. The body cells are also stimulated to take up glucose. This lowers the blood glucose level and returns it to normal. The influence of insulin and glucagon on blood glucose levels Blood glucose levels decrease because the body cells are constantly using glucose for cellular respiration. When blood glucose levels decrease, the pancreas will release the hormone glucagon which converts stored glycogen (from the liver and skeletal muscles) into glucose. This increases the blood glucose level and returns it to normal. • Blood glucose levels are maintained at a constant level (homeostasis). - When blood glucose levels are too high, insulin is released from the pancreas to convert blood glucose into glycogen in the liver and muscles to return the blood glucose level to normal. - When blood glucose levels are too low, glucagon is released from the pancreas to convert glycogen stored in the liver and muscles into glucose, which enters the blood and returns glucose levels to normal. When the glucose level in the blood increases above normal levels: Step 1 Glucose levels in the blood increase above normal levels Step 2 The pancreas is stimulated. Step 3 to secrete insulin into the blood Step 4 Insulin travels in the blood to the liver Step 5 glycogen which is then stored Step 6 The glucose level in the blood now decreases 58

Step 7 and returns to normal When the glucose level in the blood decreases below normal levels: Step 1 Glucose levels in the blood decrease below normal levels Step 2 The pancreas is stimulated Step 3 to secrete glucagon into the blood Step 4 Glucagon travels in the blood to the liver Step 5 where it stimulates the conversion of stored glycogen to glucose Step 6 The glucose level in the blood now increases Step 7 and returns to normal o The metabolic disorder, diabetes mellitus, occurs when insulin is not released or does not function properly resulting in high glucose levels. ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS Activity 1 QUESTION 1 Various options are provided as possible answers to the following questions. Choose the correct answer and write only the letter (A to D) next to the question number (1.1 to 1.4) in your ANSWER BOOK, for example 1.5 D. 1.1 The pancreas detects the amount of glucose in the blood. What does the pancreas release if blood sugar is too LOW? A The pancreas releases glucagon if blood sugar is low B The pancreas releases glucose if blood sugar is too low C The pancreas releases beta cells if blood sugar is too low D The pancreas releases insulin if blood sugar is too low 1.2 The liver normally stores blood sugar as… A glucose. B glucagon. C glycogen. 59

D Fats. 1.3 After a period of fasting, the brain makes the pancreas produce… A glucose. B glucagon. C glycogen. D insulin. 1.4 How does insulin travel around the body? A In bloodstream B In nerve cells C In the alimentary canal D In the lymph (4x2) (8) QUESTION 2 Give the correct biological term for each of the following descriptions. Write only the term next to the question number (2.1 to 2.3) in your ANSWER BOOK. 2.1 The ability of a living organism to maintain a constant internal environment despite the constant fluctuations in the outside environment 2.2 Mechanisms in the human body that detect changes or imbalances in the internal conditions and restore homeostasis 2.3 The metabolic disorder that occurs when insulin is not released or does not function properly resulting in high glucose levels. (3) QUESTION 3 Indicate whether each of the statements in COLUMN I applies to A ONLY, B ONLY, BOTH A AND B or NONE of the items in COLUMN II. Write A only, B only, both A and B, or None next to the question number (3.1 to 3.3) in the ANSWER BOOK. COLUMN I COLUMN II 3.1 Stable internal environment A Homeostasis B Metabolism 60

3.2 Chemical messengers that are secreted A Enzymes directly into the blood which carries them to B Hormones organs and tissues of the body to exert their functions 3.3 The organ that detects an increase in blood A Liver glucose B Pancreas (3 x 2) (6) Activity 2 The flow chart below shows the control of glucose levels. Provide labels for 1 to 6 Pancreas: Releases Liver and muscles: Glucose 1 ............ converted to 2 ................... Glucose level increases Glucose level 3 ...................... NORMAL GLUCOSE LEVEL Glucose level 4 .................. Glucose level increases 5 ……………………. releases Liver and muscles: Glycogen glucagon converted to 6 ............... (6) 61

Activity 3 Humans regulate the glucose concentration of their blood. A scientist recorded the blood glucose concentration of an individual over a seven-hour period. The results are shown in the table. Time of day blood glucose concentration / mg per 100 cm3 06.00 76 07.00 77 08.00 124 09.00 91 10.00 83 11.00 81 12.00 79 13.00 130 1 What is excess blood glucose converted into in the body? (1) 2 Describe the trend in blood glucose concentration for this seven-hour period. (2) 3 Suggest reasons for the changes in blood glucose concentration in blood. (2) 62

WEEK 9: TOPIC: Cellular respiration SUB-TOPIC: Process of respiration NOTES & EXAM TIPS Cellular respiration Is the chemical process where glucose is broken down gradually, in the presence of oxygen (aerobic respiration) or in the absence of oxygen (anaerobic respiration), to release energy. 1. Aerobic respiration (needs oxygen) Aerobic respiration takes place:  in the presence of oxygen;  inside the cytoplasm and mitochondria of cells. Figure 1 shows the internal structure of a mitochondrion. Figure 1 The requirements for the process are oxygen and glucose and the by-products released are carbon dioxide and water as well as ATP energy. This can be shown in the following word equation: Aerobic respiration takes place in three stages: 1. Glycolysis – takes place in the cytoplasm 2. Krebs Cycle – takes place inside the mitochondrion 3. Oxidative Phosphorylation – takes place inside the mitochondrion 63

Glycolysis  takes place outside the mitochondrion, in the cytoplasm of the cell  no oxygen is required during this stage  glucose is broken down into smaller molecules, releasing a small amount of energy that is stored in energy-rich ATP molecules  releases high energy hydrogen ions (H+) that are used in the third stage of cellular respiration (oxidative phosphorylation) Krebs Cycle  can only take place if oxygen is present  occurs inside of the mitochondrion  releases carbon dioxide and high energy hydrogen ions (H+)  transports hydrogen atoms to the third stage (oxidative phosphorylation) via hydrogen carrier enzymes Oxidative Phosphorylation  takes place inside of the mitochondrion and requires oxygen  passes high energy hydrogen atoms from one hydrogen carrier enzyme to the next, releasing energy in the process  uses released energy to combine a phosphate molecule to an ADP (Adenosine Di- phosphate) molecule to form ATP – called phosphorylation  is represented in the formula: ADP + P → ATP  oxygen acts as a final hydrogen acceptor binding with the hydrogen forming water which is released as a waste product of cellular respiration 2. Anaerobic respiration takes place: without oxygen being present  it occurs for short periods of time, mainly during physical exercise  occurs differently in plants and animals  produces less ATP than aerobic respiration Anaerobic respiration in animals is known as lactic acid fermentation and occurs in muscles during intense exercise Anaerobic respiration in plants is known as alcoholic fermentation Uses of anaerobic respiration in industry  Yeast and other fungi respire anaerobically and are used to produce alcoholic beverages such as beer and wine. 64

 Yeast cells are also used to cause bread to rise during the baking process.  The fermentation process is also used to produce cheese. The differences between aerobic and anaerobic respiration ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 1.1 Various options are provided as possible answers to the following questions. Choose the correct answer and write only the letter (A to D) next to the question number (1.1.1 and 1.1.2) in your ANSWER BOOK, for example 1.1.3 D. 1.1.1 The conversion of pyruvic acid into lactic acid occurs during … A Photolysis. B glycolysis. C anaerobic respiration. D oxidation of glucose. 1.1.2 A phase that does not require oxygen during cellular respiration is: A Krebs cycle B Glycolysis. C Oxidative phosphorylation D All of the above (4) 65

1.2 Give the correct Biological Term for each of the following descriptions. Write only the term next to the question number (1.2.1 to 1.2.10) in your ANSWER BOOK. 1.2.1 The process during which glucose is converted into pyruvic acid. 1.2.2 The reagent used to test for the presence of carbon dioxide. 1.2.3 The acid that accumulates in the muscles of humans during continuous strenuous physical activity. 1.2.4 The gas which is essential for the Krebs cycle to occur. 1.2.5 Folded structures found on the inner membrane of a mitochondria. 1.2.6 The stage of aerobic respiration that releases carbon dioxide. 1.2.7 Genetic material found in the mitochondrial matrix. 1.2.8 The stage during aerobic respiration when water is released as a waste product. 1.2.9 Chemical processes in organisms which are controlled by enzymes 1.2.10 The organelle in which respiration takes place (10) QUESTION 2 Read the information below and answer the questions that follow. Traditional African Beer forms a very important part of African culture. It is called umqombothi in isiXhosa and iJuba in isiZulu. The beer is mostly brewed from indigenous sorghum. The thick creamy African beer is very rich in vitamin B, it has a low alcohol content of less than 3% and it is inexpensive. The recipe for brewing beer is passed down through the generations. The traditional method of testing to see if the brew is ready is to light a match close to the container of beer. If the flame dies quickly, the brew is ready. If the flames remain lit, the brew is not ready. 2.1 Name the biochemical process used to brew this African beer. (1) 2.2 What causes the flame to die? (1) 2.3 Why would this test be an indication of whether the brew is ready or not? (1) (3) QUESTION 3 Tabulate the differences between Aerobic and Anaerobic respiration (9) 66

WEEK 10: TOPIC: Cellular respiration SUB-TOPIC: Investigation: CO2 is produced by living organisms during respiration NOTES & EXAM TIPS SCIENTIFIC INVESTIGATIONS: What is a hypothesis? A hypothesis is an attempt to explain some event or observation using whatever information is currently available. It is a testable statement that may be accepted or rejected. A hypothesis must: (a) have two variables (dependent and independent variables); (b) state the relationship between the two variables; (c) be testable; and (d) state the independent variable first (cause) and then the dependent variable (effect) Variables: Controlled / fixed variable – refers to the factors that should be kept constant so that the results of an investigation can be considered valid. Independent variable – refers to the factor that is being investigated. This factor is usually manipulated by the investigator either at the start of or during the course of the investigation. The independent variable appears on the X-axis of a graph. Dependent variable – refers to the effect of the independent variable. This effect is usually measured. What is reliability?  The idea behind reliability is that any significant results of an investigation must be more than a once-off finding and be repeatable.  For the questions which required learners to state how the reliability of the investigation could have been improved, the following answers apply: Repeat the investigation OR Increase the sample size. 67

What is validity?  Validity questions show how the experiment/investigation was carried out. It is important to be sure that all the factors/variables have been controlled/ fixed except the variable/factor being tested.  In questions which require learners to suggest some factors that might have decreased the validity of an investigation, the answers should centre on the criticism of the scientific process; for example, some factors/variables that were not fixed/controlled when carrying out the investigation INVESTIGATION: CO2 is produced by living organisms during respiration Living organisms produce carbon dioxide as a by-product of aerobic respiration. We can test for the presence of carbon dioxide by using clear lime water which will turn a milky colour when in the presence of carbon dioxide. Soda lime can be used to remove carbon dioxide from the atmosphere and sodium hydroxide can be added to a solution to remove carbon dioxide found in a liquid. This will ensure that no carbon dioxide can enter into any experiment so that we can prove the carbon dioxide is a result of aerobic respiration performed by an organism. Hypothesis: Carbon dioxide is produced by living organisms during respiration Aim: To prove that carbon dioxide is produced by living organisms during respiration Materials/apparatus Small organism Alcohol Large jar 3 test tubes Rubber stoppers with 2 holes Glass tubes Electric pump Soda lime Sodium hydroxide solution Lime water Method:  Use a small organism (e.g. snail).  Sterilise the equipment so that no micro-organisms can influence the result.  Place the snail into a large jar.  Set- up the apparatus as shown in the figure below, making sure that the test tubes are tightly sealed.  Examine the test tubes the following day and record the results. 68

Results:  Test tube B: the lime water remains clear, carbon dioxide is removed by the soda lime and sodium hydroxide.  Test tube D: the lime water turns milky due to carbon dioxide produced by the snail. Conclusion: Carbon dioxide is produced during respiration by living organisms (the snail) ACTIVITIES/WORKSHEETS/EXAM TYPE QUESTIONS QUESTION 1 The apparatus below was used to carry out an experiment on aerobic respiration. The experiment was set up as follows:  Seeds of the same kind were used  The seeds and the apparatus were sterilised before the investigation  Once set up, the apparatus was placed in a dark cupboard at 35°C. A control was also set up 69

Cotton wool plug Germinating seeds Cotton wool plug Clear lime water 1.1 What would be the hypothesis for the experiment shown above? (2) 1.2 What is the significance of sterilizing the seeds before they are used? (1) 1.3 Give one controlled variable in this investigation. (1) 1.4 Explain how you would set up a control for this experiment. (2) 1.5 What would be the purpose of setting up a control experiment? (2) 1.6 Explain why germinating seeds were used in this investigation. (2) (10) 70