Biology Exam Paper PDF

Question Answer The ciliary muscle contracts,...

Question Answer The ciliary muscle contracts, relaxing their pull on the The ciliary muscles contracts,relaxing their pull on the suspensory ligaments. The suspensory ligament. The suspensory ligament slacken, suspensory ligaments slacken, realaxing their pull on the lens. The lens, being elastic, relaxing their pull on the lens. becomes thicker and more convex to focus light from a close The lense will become thicker How does eyes focused on a image of a near objects on the retina? object and more convex The ciliary muscle relax ,pulling the suspensory ligaments. Suspensory ligaments become taunt , pulling the edge of the How does eyes focused on an imaged of a distant object on the lens. The lens becomes thinner and less convex,to focus light retina? from a far way object The ciliary muscle will relax, pulling the suspensory ligaments. The suspensory ligaments become taunt, pulling the eduge of the lense. The lens becomes thinner and less conve x The circular muscle of the iris will contract. The radial muscles of the iris relax. The pupil will constricts,reducing the amount of How the pupil reflex in response to bright light light entering the eyes The circular muscle of the iris will contract. The radial muscle will relax. The pupil will then constrict The circular muscle of the iris will relax, the radial muscles of the iris contract. The pupil becomes larger hence more light will How the pupil reflex in response to dim light enter the eyes The circular muscle will relax, the radial muscle of the iris contract. The pupil becomes larger Pupil reflex is beneficial for individuals as it control the amount of light that enters the eyes and prevents excessive light from Describe how pupil reflex is beneficial to the individual damaging the retina Rods enable us to see in back and white under dim light while State the function of rods and cones in the retina cones enable us to see colours under bright light It is the usage of 2 eyes to perceive a single three-dimensional Define Binocular vision image of the surrounding Our brain fuses the two images, so we perceive the relative and Why two eyes are needed for binocular vision absolute depths of objects in space.  It is the unit of life consisting of a mass of living Define cell matter called protoplasm It is selectively permeable membrane which only What is the function of Cell surface membrane allows certain substances to pass through it. It protects the cell from injury and gives the plant a fixed shape. It is fully permeable so it does not What is the function of Cellulose cell wall? control the type of substances that enter the cell It is when most cell activities occur. It contains What is the function Cytoplasm? organelle 1. Surrounded by a membrane called the nuclear membrane It control cell activities such as cell growth and repair of worn-out parts. It is essential for cell What is the function of Nucleus division Each chromosome is a long thread-like structure What is the chromosomes found within the nucleus (46 chromosomes It surface appears rough when viewed under the microscope, this is because small particles known What is the rough endoplasmic renticulum (RER) as ribosomes are attached to its outer surface Its function is to modify the proteins made by the ribosomes/ transport protein from the ribosomes to the Golgi body for secreation out of the cell It does not have any ribosomes attached to its membrane. It is mire tubular than RER. It is also connected to the RER It synthesises substances such as fats and What is the smooth endoplasmic renticulum (SER) steroid, and converts harmful substances into and its function? harmless substances through detoxification Ribosomes are small round structures, They are either attached to the membrane of RER or lie freely in the cytoplasm. They are needed to synthesise proteins in the cell. They attached to the RER to make protein that are usually transported out of the cell. Those lying freely around the cytoplasm make protein that are used What is the ribosomes within the cytoplasm of the cell Vesicles can be seen fusing with one side of the Golgi body and pinching off from the opposite side. The Golgi body chemically modifies substances made by the endoplasmic reticulum and stores and packages these substances in vesicles for secretion out of the What is the Golgi body? cell. Small oval organelles where aerobic respiration occurs. During this process, food substances are broken down to release energy which are used by the cell to perform cell activities such as growth and reproduction It helps to aid the production of ATP which is essential for What is mitochondria (singular: mitochondrion) muscle contraction and relaxation  It has double membrane surround a matrix and the inner membranes fold inward to form Cristae (s:crista) Vesicles containing (substances) made by the rough endoplasmic reticulum pinches off from the RER. The vesicles fuse with the Golgi body releasing the molecules made by the ER which may be modified. Secretory vesicles contains modified molecules pinch off from the Golgi body and move towards the cell surface membrane. Explain how the substances made by the ER are The secretory vesicles fuse with the cell surface moved out of the cell membrane and their content exit the cell. Contains chlorophyll which is essential for What is the function of chloroplasts photosynthesis Double membranes enclose a fluid space called stroma Third inner membrane called thylakoid membrane which form thylakoid. A stack of thylakoid is knows as granum (p:grana). The thylakoid membrane contains chlorophyll. It is a fluid-filled space enclosed by a partially permeable membrane. Pant cells have a large central vacuole which contains a liquid called cell sap which contains dissolved substances such as sugars, mineral salts and amino acids. Animal cells have many small vacuoles that contains water and food substances which usually What is the vacuoles exist temporarily In plant cell cell wall is present while in animal cell, cell wall is absent There is a presence of a large, central vacuole in What is the difference between plant and animal the plant cell while in animal cell there is presence cells? of many small vacuoles Circular biconcave shape: to increase the surface area to volume ratio so that oxygen can diffuse in Red blood cells and out at a higher rate Contains haemoglobin which binds to oxygen and transport it around the body Lack of nucleus: Allows the cell to store more haemoglobin for transport of oxygen Flexible: So that it can squeeze through the capillaries easily It has long and narrow root to increase the surface area to volume ratio to absorb water and mineral Root hair cell salts at a higher rate It is elongated and cylindrical in shape: contains Skeletal muscles cell many nuclei and mitochondria Has mitochondria: to provide energy for the contraction of muscle cell Tubular multi nucleotide striate fibre: allows movement of the body  The central nervous system (CNS) consists if the brain and spinal cord The peripheral nervous system (PNS) consists of What are the components for the Human Nervous the cranial and spinal nerves as well as the sense System? organs When there is a stimulus, the receptor in our sense organs are stimulated to produce nerve impulses. These nerve impulses are transmitted by nerves to the central nervous system (CNS). The central nervous system then sends the nerve impulses to How does CNS and PNS work together? the effectors which are either the muscles or gland Circular cell body with one long nerve fibre between receptor and cell body. There is one short Sensory neurone nerve fibre between cell body and CNS Irregular shape cell body with one long nerve fibre between the cell body and the effector (muscle Motor neurone fibre) Function: To relay impulses dorm the sensory Relay neurone neurone to the motor neurones A synapse is the junction between two neurones. Nerve impulses are transmitted across a synapse What is a synapse? by chemicals released by the neurones It is an immediate response to a specific stimulus without conscious control. This included spinal It is an immediate response to a reflaxcontrolled by the spinal cord and Cranial specific stimulus without conscious Define reflex action reflex's controlled by the brain control. The heat from the object stimulates the nerve endings in our skin. Nerve impulses are produced. The heat from the object stimulates The sensory neurone transmits the nerve impulses the nerve endings in our skin. Nerve to our spinal cord. In our spinal cord, the nerve impulses are produced. The sensory impulses are transmitted first across a synapse to neurone transmits the nerve The heat from the object stimulates nerve the relay neurone , and then across another impulses to out spinal cord. Our ending in our skin. Nerve impulses are synapse to the motor neurone. Our biceps muscle biceps muscle then contracts and produced. The sensory neurone trans,its the Describe what happen when your hand touched hot then contacts and causes our hand to withdraw cause our hand to withdraw nerve impulses to our spinal cord. Our bicep object suddenly. suddenly. then contracts and withdraw suddenly=y It is the shortest pathway by which nerve impulses It is the shortest pathway nerve travel from the receptor to effector in a reflex impulses travel from the receptor to action. the effector in reflex action Receptor to the sensory neurone to the relay Define reflex arc neurones to the motor neurone and the effector Both controls serve as the men of co- Both controls serve as the means of co- ordination within the body. In both ordination within the body. In both cases, a cases, a stimulus causes the stimulus causes the transmission of message transmission of message to a target to a target organ that carries out the response. organ that carries out the response Endocrine control involves hormones as signals while nervous control involves nerve impulses as signals The hormones are transported by the blood while Compare endocrine and nervous controls. the nerve impulses are transmitted by the neurones Voluntary action are activities that are controlled What is the difference between voluntary and consciously while involuntary actions are activities involuntary action? that are not controlled consciously  Through metabolic activities such as respiration within the body, vigorous physical activities and How does our body gain heat ? consumption of hot food and drink From the skin through convection, radiation and conduction. Evaporation of sweat and faeces and How does our body lose heat? urine Excess heat needs to be removed from the body, if What happens if our body does not lose heat? not, one could die of overheating When our body temperature ruses above normal, thermoreceptors in the skin and the hypothalamus are stimulated. The aterioles in the skin will dilates, this allows more blood to flow through. Hence When our body temperature rises above normal. The more heat will be lost through the skin. Sweat thermoreceptors in the skin and the hypothalamus are glands will also become more active and produce stimulated, The aterioles in the skin will dilates more sweat. As more water in the sweat allowing more blood to flow though. Hence more heat evaporated from the surface of the skin, more heat can be lost through the ski Swaet Ganda will also is lost from the body. The metabolic rate is become more active and produce more swears, As decreased. This reduces the amount of heat more water in the sweat is evaporated from thhe What happens when body temperature increases released within the body surface of the skin, more heat is lost from the body When our body temperature falls below normal. Thermoreceptor in our skin will be stimulated. Impulse;she's are transmitted to the hypothalamus in the brain. The arterioles in the skin will constrict. This allows less blood tot flow through the blood capillaries in the skin. Hence, less heat will be lost through the skin. Sweat gland will also become less active and produce less sweat. As less water in the sweat evaporates from the surface of the skin, less heat is lost from the body. When the above response is not sufficient to prevent a drop of temperature, shivering occurs. This rapid contraction and relaxation of the skeletal muscles What happens when body temperature decreases increases the amount of heat released  Is the difference in concentration between 2 What is concentration gradient? regions It is the net movement of particles from a region where they are of a higher concentration to a region where they are of a lower concentration What is diffusion? (Simple vs facilitated) (simple diffusion) The diffusion of substances through cell membranes using specific protein channels or carriers from regions where they are at higher concentrations to regions where they are at lower What is facilitated diffusion? concentrations. 1. Concentration gradient What are the factors that affect the rate of 2. Diffusion distance diffusion? 3. Surface area-to-volume ratio It is the net movement of water molecules from a region of higher water potential to a region of lower water potential through a partially/ selectively What is osmosis ? permeable membrane. It is the measure of the tendency of water to move from one place to another A diluted solution has a higher water potential What is water potential? (Highest water potential is 0) The cell sap has a lower water potential than surrounding solution. By osmosis, water molecules enter the cell through the partially permeable membrane. The cell expands and becomes turgid. As water molecules enter the cell, the vacuole increases in size and pushes the cytoplasm against the cell wall. The cell does not What happens to plant cell in a solution with burst because it is protected by the inelastic cell higher water potential? wall. The cell sap has a higher water potential than the surrounding solutions. By osmosis, water molecules from the vacuole and cytoplasm leave the cell through partially permeable cell membrane. The cell decreases in size and becomes limp. As the cell loses water, the vacuole decreases in What happens to plant cell in a solution with lower size. The cytoplasm shrinks away from the cell water potential? (Also known as plasmolysis) wall. Animal cell will swell and may even burst in a solution of higher water potential than its What happens to an animal cell in a solution with cytoplasm. This is because unlike plants, it does higher water potential? not have a cell wall to protect it. A cell immersed in a solution with the same water potential as its cytoplasm will not change its size or shape. The movement of water molecules is the What happens to an cell in a solution of the same same in both directions hence there is no net water potential? + movement of water molecules in or out of the cell. It will cause the anomaly cell to lose water. The cell What happens to an animal cell in a solution with will then shrinks and spikes appear on the cell. It lower water potential? (Known as crenation) will become dehydrated and eventually die.  The process in which energy is used to move the particles of a substance across a membrane against its concentration gradient. from a region where the particles are of a lower concentration to What is Active Transport a region of higher concentration. Requires cellular energy in the form of adenosine triphosphate (ATP) Cell surface membrane of root hair cells to absorb minerals ions needed Cell surface membrane id intestinal epithelial cell to absorbs nutrients, such as glucose and amino Where does active transport happens at? acid from intestine into the body. Diffusion Active transport Net movement of particles from a region of higher Net movement of particles from a region of lower concentration to a region of lower concentration, concentration to a region of higher concentration, down a concentration gradient. against a concentration gradient. Energy from respiration not required Energy from respiration required Cell membrane not required Cell membrane required Occurs by movement of edibles of matters across What is bulk transport the cell surface membrane Process by which cells export products such as What is exocytosis enzymes by means of vesicles What is endocytosis Process when substances imported into cell What are the chemical elements that make up proteins Carbon,hydrogen,oxygen, nitrogen and sulphur Long chains of amino acids folds to give proteins amino acid -> polypeptide -> protein Synthesis of new cytoplasm;Lum for growth and repair of worn out body cell Synthesis of enzymes and some hormones. What are the functions of proteins Structure of proteins: Unique sequence and number of amino acids held together by peptide bonds that make up a Primary structure polypeptide chain. Dowsing and coiling of parts of the polypeptide to Secondary structure form alpha helix and beta pleated sheet. Final unique three-dimensional structure of Tertiary structure polypeptide Two or more polypeptides are involved in forming Quaternary structure biologically functional protein. What are the chemical elements that make up carbohydrates? Carbon,Hydrogen,Oxygen (3 elements) Glucose (in plant and animal) Simple sugar: Fructose (common in plants but rare in animals) Double sugar: Maltose (two glucose molecules bonded together) Sucrose ( one glucose molecule and one fructose molecule) Complex carbohydrates (polysacchrides) Structure Role Occurrence Several thousand glucose molecules joined Storage organs of plants such as Starch together Storage of carbohydrates in plants potato turner or tapioca Cellulose cell walls protects plant Many glucose molecules joined together but cells. Serve as dietary fibres to Cellulose bonded differently from started prevent constipation Cell walls of plants storage form of carbohydrates in Stored in liver and muscles of Glycogen Branched molecule of many glucose molecules animals mammals What are the chemical elements in fats Carbon,Hydrogen and Oxygen How can fats be broken down Glycerol and three fatty acid molecules Suitable long-term storage material because fats have higher energy value compared to carbohydrates Some functions of fats An insulating materials that prevents excessive heat loss.  A substance that can speed up a chemical reaction What is a Catalyst (also known as enzymes in without itself being chemically changed at the end living organisms) of the reaction The energy needed for a chemical reaction to be What is activation energy activated Enzymes are proteins that function as biological catalysts. They catalyse or speed up the rate of chemical reactions. They remain chemically what are enzymes? unchanged at the end of the reaction. 1. Build up complex substances from.a simpler ones 2.Break down complex substances to simple What reactions do enzymes catalyse substances 1. Speed up chemical reactions 2. Enzymes are specific in action 3. Enzymes are required in small quantities and What are the characteristic of enzymes remain chemically unchanged at the end of the reaction 4. Enzymes are affected by temperature. 5. Enzymes are affected by pH The shape of active site of the enzyme is specific and complementary to the shape of the substrate. Upon effective collisions between enzyme and substrate, the enzyme-substrate complex is Describe how an enzymes intersect with its formed. Intersections between enzymes and substrate substrate molecules weaken chemical bonds within substrates, Thus,lowering activation energy. When reaction between substrate and enzymes is completed, product no longer fit into active site of enzymes. Enzymes alter the rates of chemical reactions that occur in a cell. Enzymes speed up a chemical How Enzymes speed up chemical reaction reaction by lowering the activation needed to start the reaction. Enzymes have active sites. Only substrates with a shape complementary to the active site can fit into the enzymes. When an enzymes binds to its How are enzymes specific in action substrates, it forms an enzyme-substrate complex. However, high temperature,acids and alkalis can affect the shape of an enzyme and consequently its function. Enzymes are vey efficient molecules, since they remain unchanged in the reactions they catalyse, the same enzyme molecules can be used over and Why enzymes are required in minute quantities over again. Thus a small amount of an enzymes and remain chemically unchanged at the end if the can catalyse the reaction for a large amount of reaction? substrate. For example, just a spoonful of washing powder containing enzymes is enough to wash a large load of clothing  According to the lock-and-key hypothesis, enzymes reactions depend if the presence of active site. Active sites are grooves or "pocket: on the surface of the enzymes molecule into which the substrate milecule with the matching shape can fit. When the substrates binds to the active site of What is the lock-and-key hypothesis? enzyme, an enzyme-substrate complex is formed. Interactions between enzyme and substrate molecules weaken chemical bond and within substrates. Thus, lowering activation energy. When reaction between substrates and enzymes is completed,products no longer fit into active site of enzymes. Products are released. For every 10 degree rise in temperature, the rate of enzyme reaction is increased until the optimum temperature is reached. Enzyme is inactive at low temperature due to low kinetic energy; the frequency of effective collision is low. As temperature increases , kinetic energy of the substrate and enzyme molecules increases, thereby increases the frequency of effective collision between the substrates and enzyme active sites, which increases the rate of enzyme- substrate complex and increases the rate of reaction. Enzymes activity is highest at its optimum temperature of ( ). When the temperature is increases beyond the optimum temperature of ( ), higher temperature brea the bonds that keep the enzyme protein in its specific shape. The active site lose its original shape and is no longer complementary to the substrate. The enzyme is How temperature affects enzymes denatured and loses its catalytic function All enzymes have an optimum pH in which it functions most efficiently. Rate of reaction is at a maximum (specify) Enzymes maintains its specific shape and so the enzymes active site is complementary to the substrate. Enzymes binds the substrate to form the enzyme-substrate complex. Substrate is converted to product. Changes in pH (specify) can affect enzyme activity. Structure of the protein is maintained by various bonds. Changes in pH alter the bonding pattern, thereby altering the 3D shape of the enzyme. Hence, the substrate is no longer complementary to the active site. No enzyme- substrate complex can be formed. The enzyme is How pH affects enzymes denatured and loses its catalytic function.  The study of how organisms mange their energy resources using either anabolic pathways or Define Bioenergectics catabolic pathways. Autotrophs Heterotrophs Make their own organic matte from inorganic Cannot make organic molecules form inorganic nutrients though anabolic reaction ones Consumers because they eat other organisms to Producers because ecosystems depend upon obtain energy from food through catabolic them for food reactions Photosynthesis Cellular respirations Internal structure of leaf Closely packed cells form on layer and do not 1. Upper epidermis contain chloroplasts 2. Palisade mesophyll (where photosynthesis The closely packed,long and cylindrical cells occur) contain the most number of chloroplasts 3. Spongy mesophyll (where photosynthesis The loosely packed and irregular-shaped cells occurs) contain chloroplasts. The closely packed cell form one layer and do not 4. Lower epidermis contain chloroplasts Adaptation Function Reduces water loss through evaporation from the Waxy cuticle on upper and lower epidermis leaf. It is transparent for light to enter the leaf. Stomata a opens in the presence of light, allowing carbon dioxide to diffuse in and oxygen to diffuse Stomata present in the epidermal layers in and oxygen to diffuse out of the leaf Chloroplasts containing chlorophyll in all Chlorophyll absorbs energy from light and transfers mesophyll cells it to chemical stored of energy in glucose molecule More light can be absorbed near the upper leaf More chloroplasts in upper palisade tissue tissue Interconnecting system of air spaces in spongy The air spaces allow rapid diffusion of carbon mesophyll dioxide and oxygen into and out of mesophyll cells. Xylem transport water and mineral salts to Veins containing xylem and phloem situated close mesophyll cells. Phloem transports sucrose away to mesophyll cells from the leaf. Stomata open as a result turgid guard cells. Light triggers the active uptake of potassium ions by guard cells from nearby cells. Lowers the water potential of guard celll and water enters by osmosis. The uneven thickness of cell walls of guard cells result in the cells bowing with water intake, opening the pore of the stoma. Stoma close when water leaves the guard cells by diffusion of potassium ions out of the guard cells. This increases the water potential of the guard cells and water leaves by osmosis. The guard cells How do guard cells control the size of stomata become flaccid and the stoma closes Carbon dioxide diffuse into the lead through stomata. It dissolves in the water around the cells. How Does carbon dioxide enter the leaf cels It then diffuse into the cells. Water and mineral salts are transported through How do the leaf cells receive water and mineral the xylem vessels from the root, they move from salts? cell to cell through the mesophyll. Functions of Xylem Adaptation of xylem To conduct water and mineral salts up from the Long hollow tube made up of dead cells without roots cross walls To provide mechanical support There is lignin on the inner walls Function of Phloem Adaptation of Phloem A column of sieve tube cells or sieve tube Need to be living cells as energy will be needed to elements forms a long sieve tube. transport food The sieve plants, which are cross-wall between the cells have many munite pores To transport food from the leaves to other parts of The companion cell of each sieve tube cell the plant provides nutrients and help it to transport food.  The process where products of photosynthesis are translocated via the phloem from production sites What is Translocation in green leaves to parts where they are utilised. The sucrose molecule moves from the mesophyll cells in the leaf to the phloem in vascular bundle of the leaf. This is followed by movement to the Describe the pathway travelled by a sucrose phloem in a vascular bundle of the fruit and finally molecule as it is transported from the leaf to a sink to the cells of the fruits. Draw in the vascular bundles in a plant 1. By diffusion when concentration of ions in the soil solution is higher than that in the cell sap. Ions How do root hairs absorb ions or mineral salts? diffuse 2. By active transport when concentration of ions in the soil solution is lower than that in the cell sap. Ions are absorbed against a concentration gradient. Capillary action is the ability of a liquid to flow through narrow spaces without any assistance and even against gravity. It occurs when the adhesive forces between the liquid and the walls of the space are stronger than the cohesive forces between the liquid molecules. This helps water to move up the narrow xylem vessels of plants. While water is taken into plants through their roots, it is also evaporating through the stomata of the leaves. The loss of water vapour through the stomata is known as transpiration. As transpiration occurs, a suction force is created, drawing water up from the roots to the leaves. This force is called What is capillary action transpiration pull. Factors affecting rate of transpiration Explanation Increase molecular movements so that more water molecules evaporate from cell surface; the rate of diffusion of water molecules from the leaf is Temperature increases Reduces the concentration of water molecules outside the lead, diffusion of water from the leaf Humidity increases. Removes water Vapor from leaf surface, more water diffuses from the leaf because a high Air movement concentration gradient is maintained Increases s the rate of photosynthesis; stomata Light intensity open so that water diffuses out of leaf Wilting occurs when the rate of transpiration is When does wilting occurs higher than the rate of absorption of water by roots Advantages of wilting Disadvantages of wilting Closure of stomata reduced amount of carbon Reduction in rate of transpiration dioxide entering the leaf Reduction in lead surface area expose to light Carbon divide becomes a limiting factor Reduced exposure of stomata at atmosphere Decrease in the rate of photosynthesis Reduced rate of water loss through stomata Folding a leaf reduces surface area exposed to light Excessive lose of water causes guard cells to become flaccid and stomata to close  A thin film of moisture surrounds the mesophyll cells. Water evaporates from this thin film to form water vapour in the intercellular air spaces. Water vapour then diffuses through the stomata to the drier air outside the leaf. This is transpiration. As water evaporates from the thin film of moisture, more water moves out from mesophyll cells to replenish it.As water is lost from the mesophyll, the water potential of their cell sap decreases and becomes lower than that of their neighbouring mesophyll cells. The mesophyll cells draw water from cells deeper inside the lead by osmosis. The cells deeper inside the ;ear then draw water from the xylem by osmosis. This creates a suction force which pulls the whole column of water up the Describe the movement of water through leaf xylem vessels which is known as transpiration pull. What is the equation for photosynthesis? It converts energy firm the sun into chemical energy which is needed by other organisms Why is photosynthesis important It removes carbon dioxide from the atmosphere. It produces oxygen needed for respiration by other organisms It contributes to the energy stored in fossil fuels What are the conditions for photosynthesis Light,carbon dioxide, chlorophyll, suitable temperature, water Site of Photosynthesis Light energy absorbed by chloroplasts pigment is used in photolysis of water molecule, formation of NADPH & ATP. What is light dependent stage (in granum) Oxygen is released as a by products. Requires continuous supply of ATP and NADPH (products of light dependent reaction) to reduce carbon dioxide to carbohydrates. What is light independent stage (Calvin cycle) (in Cycle process involving three main steps: stroma) 1. Carbon fixation 2. Reduction 3.Regeneration of RuBP Carbon dioxide diffuses into the stroma and combines with RuBP 1. Carbon fixation Product: Glycerate 3 phosphate (GP) GP is reduced to triose phosphate by NADPH and AYP Energy from ATP and hydrogen from NADPH are used ti reduce GP to triose phosphate 2. Reduction Products: Carbohydrates,lipids and amino acids RuBP is regenerated using energy ATP, so that more carbon 3. Regeneration of RuBP dioxide can be fixed Calvin Cycle compounds 1. It is used immediately 2. It is converted to starch and stored temporarily What happens to the glucose that is formed during 3. It is converted to sucrose and transported away to be stored photosynthesis 4. It is converted to amino acids to proteins Factors affecting rate of photosynthesis Explanation As light intensity increases , the rate of photosynthesis increase until a constant rate (38%) is reached. More light means more Light intensity energy for photosynthesis. As carbon dioxide concentration increases, the rate of photosynthesis increases until constant rate is reached. (0.1%) Carbon dioxide concentration More carbon dioxide means more glucose can be produced. As temperature increases to the optimum temperature (25-35), the rate of photosynthesis increases. As temperature increases beyond optimum temperature, the rate of photosynthesis Temperature decreases. What is the similarities between anaerobic and Both processes involve oxidation aerobic respiration Both processes release energy Aerobic respiration Feature of comparison Anaerobic respiration Presence of oxygen Availability of oxygen Absence of oxygen Realises all available energy energy produced release less energy Produces lactic acid in mammals (muscles cells) Produces CO2 and H2O Other by products and ethanol and carbon dioxide in yeast Mitochondrion ( and cytoplasm) Location Cytoplasm Can be studied using plants, small organism or microorganisms Common organisms used in study can be studied using yeast 1. Involves breakdown of glucose in the presence of cygen 2. Produces carbon dioxide and water as waste products 3. Generates large amount of energy in the form of ATP Features of aerobic respiration 4. Location f process is at mitochondria 1. continuos of fast heart rate: results in a continued and fast transport of lactic acid from the muscles to the liver and oxygen from the lungs to the liver 2. Continuous of deeper and faster breathing which can result in continued and fast intake of oxygen by lungs. Sufficient How can oxygen debt ( lactic acid) be removed oxygen is required to remove the lactic acid from the blood. after a race? Once the acetic acid is removed, the oxygen debt is repaid Parts of the human gas exchange system: Pharynx Larynx The thrachea is suppprtted by C-shaped rings of cartilage that thrachea ( the windpipe) reps the lumen of the trachea open. Cleanses, warms and moistens air entering the lungs. Mucus secreted by gland cells raps bacteria and dust particles. Contains cilia which sweep the mucus up the throat The thrachea dives into two tubes called bronchi (singular: bronchus) Each bronchus carries air into the lung. The bronchi are similar in structure to the trachea. Each bronchus branched Bronchi and Bronchioles repeatedly, giving rise to numerous bronchioles. Bronchioles are very fine tubes. Each bronchiole ends in a cluster of air sacs aka alveoli Gas exchange take place though the walls of alveoli. Numerous alveoli are found in the lungs, providing a very large surface Alveoli area for gas exchange. Structure of alveoli Gas exchange in the lungs occurs by diffusion. Blood entering the lungs has a lower concentration of oxygen and a higher concentration of carbon dioxide than the atmospheric air entering the alveoli in the lungs. A concentration gradient for oxygen and carbon dioxide is set up between blood and alveolar air. Oxygen dissolves into thin film of moisture on the wall of the alveolus. The dissolved oxygen then diffuses through the wall of the alveolus and the wall of the blood capillary into the red blood cells. The oxygen combines with haemoglobin to form oxyhemoglobin. Carbon dioxide diffuses from the blood into the alveolar air. How does gas exchange occur in the alveoli There are two sets of muscles, the external and internal intercostal muscles. They are antagonistic muscles. This means that when the external intercostal muscles contract, the internal What are the muscles in thoracic (chest) cavity intercostal muscle relax.  Diaphragm muscle contracts and the diaphragm flattens. The external intercostal muscles contract while internal intercostal relax. Ribs will move outwards and upwards, sternum also move up and forwards. The volume of thoracic cavity increases. The air pressure inside the lungs decreases while lungs expands. The atmospheric air is forced into the lounges as teh atmospheric pressure is now higher than the What happens during inspiration? pressure within the lungs. Diaphragm muscle relaxes and the diaphragm arches upwards. The internal intercostal muscles contacts while external intercostal muscles relax.Ribs will move inwards and downwards. Sternum also moves down to its original position. The volume of thoracic cavity decreases. Lung is then compresses and air pressure inside the them increases as the volume decreases. Pressure within the lungs is now higher than the atmospheric pressure. The air is forced out of the lungs to What happens during expiration? the exterior environment. What effects does tobacco smoke have on human health?