L9 Respiration and Photosynthesis PDF

Respiration and photosynthesis  Respiration Objectives: 1. Understand why living organisms respire 2. State the word equation for aerobic respiration 3. Understand how living organisms obtain the raw materials needed for respiration Why do we respire?...

Respiration and photosynthesis  Respiration Objectives: 1. Understand why living organisms respire 2. State the word equation for aerobic respiration 3. Understand how living organisms obtain the raw materials needed for respiration Why do we respire? What chemical substances are needed for respiration? What substances are made as a result of respiration?  Respiration Respiration is a life process which occurs in all living organisms, in all cells, continuously It is a reaction which releases energy from the sugar glucose. It provides the energy to carry out processes such as movement, growth and reproduction Respiration converts the stored chemical energy in glucose into other forms of energy that cells can use and release some heat.  Respiration Aerobic respiration uses oxygen The word equation is Glucose + oxygen → carbon dioxide + water + energy  Humans obtain oxygen from the air by breathing. When we inhale oxygen passes into the lungs. At the end of the all the branched tubes in the lungs are little air sacs called alveoli, which are surrounded by blood vessels. Blood arrives at the alveoli which has very little oxygen, the oxygen then moves from the lungs into the blood, where it is pumped all around the body by the heart.  Aquatic animals obtain oxygen from water e.g. fish use gills. Plants absorb oxygen through the tiny holes called stomata in surface of their leaves Single celled organisms like bacteria and yeast absorb it through their cell membranes  Animals obtain the sugar glucose from food they have eaten. If sugary food is eaten the glucose it contains can be immediately respired If starchy food like bread is eaten, the starch has to be digested and broken down into glucose first. Glucose then moves from the small intestine where it is digested into the blood so it can be delivered to every cell that needs it for respiration.  Respiration uses oxygen and makes carbon dioxide so the composition of the air we inhale is different to the air we exhale  We can see the oxygen has gone down by 4% (what we have absorbed) And the carbon dioxide has increased by 4% - (what we have made as a waste product)  The rate of respiration Respiration is a chemical reaction. Things that will effect the rate of respiration include Concentration of glucose (sugar) Concentration of oxygen Temperature When there is a high concentration of the required substances for the reaction (reactants) the reaction can proceed quickly. Also warmer temperatures give the molecules more energy to move around and react, so the reaction is faster  Respiration Respiration is a life process which occurs in all living organisms, in all c_________, continuously. It is a c_______________ reaction which releases e_____________ from compounds like the sugar g______________. It provides the energy to carry out life processes such as ……………………………………….…………………………………………………………… Respiration converts the c___________ energy in food into other forms of energy that cells can use. Respiration also gives off some h_______. Aerobic respiration uses oxygen. The word equation is: g___________ + o_____________ → c_____________________ + w____________ Humans obtain oxygen from the air by b______________. When we inhale, oxygen passes into the l________. At the end of the all the branched tubes in the lungs are little air sacs called alveoli, which are surrounded by b__________ vessels. Blood arrives at the alveoli which has very little oxygen, the oxygen then moves from the lungs into the blood, where it is pumped all around the body by the h____________. If sugary food is eaten, the glucose it contains can be immediately respired. If starchy food like bread is eaten, the starch has to be d__________________ and broken down into glucose first. Glucose then moves from the small intestine where it is digested into the blood so it can be delivered to every cell that needs it for respiration. Exhaled air contains 4% more _______________________ and 4% less _______________________ compared to inhaled air.  When yeast (single celled fungi) respire they also give off carbon dioxide We can see bubbles of gas being made in a yeast solution. The CO2 gas also makes bread rise when the dough is left to stand before baking  Design an experiment to see how the mass of glucose affects respiration in yeast. Independent variable = mass of glucose (suggest 5 masses) Dependent variable= what is measured. What could you measure that shows different rates of respiration? Controlled variables= what should be kept constant (mass of glucose is the only variable that should change) Equipment list? Hypothesis? Photosynthesis  Plants have special cells that allow them to photosynthesise Some of these cells are in the leaf. They contain special organelles (sub- cellular structures) called chloroplasts which can trap light energy Other special cells are root hair cells which provide a large surface area for absorbing water from the soil. Cross section of a leaf  You will learn more about the different types of cells in organisms in Year 9 and do not need to know all of the different cell types / tissues shown in this diagram. This picture is showing us that there are specific cells in leaves that contain chloroplasts (the palisade mesophyll cells) and these cells are the ones which trap sunlight (light energy) and carry out photosynthesis  Chloroplasts in palisade cells. Chloroplasts are organelles – sub- structures of the cell with a specific job. Chloroplasts are green because they contain a green pigment called chlorophyll. Chlorophyll traps light energy and allows the chemical reaction of photosynthesis to occur Diagrams of plant cells You do not need to be able to draw or label these cells in Year 7  Stomata are small pores (holes) in the surface of the leaf that allow gas exchange  Photosynthesis converts light energy into chemical energy. The word equation: Carbon dioxide + water → glucose + oxygen Glucose is a sugar hence we say that plants make their own food. This is why they are are called autotrophs.  Plants get water from the soil through their roots, it travels up the stem to the leaves. Plants get carbon dioxide gas from the air – it travels into the leaves through the stomata. Oxygen gas is a waste product of photosynthesis which is released through the stomata  Forests are called the lungs of the Earth because of the oxygen they release- all organisms need oxygen to respire. This is one reason why global deforestation is a major concern.  Photosynthesis Photosynthesis is the process of converting c________ d__________ (absorbed through the l_________) and w_______ (absorbed by the r________) into g________ and o________ in the presence of chlorophyll and l_______. C_______ d_________+ w_______ → g__________ + o__________ Plants ‘make their own food’, this is why they are called auto__________. Chlorophyll is a green pigment found in the c____________ of most leaf cells. Chlorophyll absorbs l_______ energy (this can be from the sun or a lamp). The chloroplasts convert l__________ energy into c___________ energy (in glucose (a sugar)). The energy in glucose can then be released during r____________ and used to help the plant grow and reproduce. Photosynthesis releases _________ as a waste product, this gas is vital for all organisms on earth, therefore deforestation is a major concern.