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Biology-11 : 12 : Respiration in Plants - Flashcards

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Why is breathing essential to life?
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Breathing is connected to the release of energy from food required for life activities such as absorption, transport, movement, reproduction, and breathing itself.
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# Question Answer
1 Why is breathing essential to life? Breathing is connected to the release of energy from food required for life activities such as absorption, transport, movement, reproduction, and breathing itself.
2 What is the source of energy for all life processes? Energy is obtained by oxidation of macromolecules called food.
3 Which organisms can prepare their own food? Green plants and cyanobacteria can prepare their own food through photosynthesis.
4 What happens during photosynthesis? Light energy is trapped and converted into chemical energy stored in carbohydrates like glucose, sucrose, and starch.
5 Why do non-green parts of plants require food? Only cells containing chloroplasts perform photosynthesis, so non-green tissues require transported food for oxidation.
6 What type of nutrition do animals show? Animals are heterotrophic and obtain food directly or indirectly from plants.
7 What are saprophytes dependent on? Saprophytes like fungi depend on dead and decaying matter.
8 What is cellular respiration? Cellular respiration is the mechanism of breakdown of food materials within the cell to release energy and trap it as ATP.
9 Where does photosynthesis occur in eukaryotes? Photosynthesis occurs in chloroplasts.
10 Where does the breakdown of complex molecules occur in eukaryotes? It occurs in the cytoplasm and mitochondria.
11 Define respiration. Respiration is the breaking of C - C bonds of complex compounds through oxidation within cells, releasing energy.
12 What are respiratory substrates? Compounds oxidised during respiration are called respiratory substrates.
13 Which respiratory substrate is usually oxidised to release energy? Carbohydrates are usually oxidised to release energy.
14 Can proteins and fats act as respiratory substrates? Yes, proteins, fats, and even organic acids can be used under certain conditions.
15 Why is energy not released in a single step during respiration? Energy is released in slow, step-wise enzyme-controlled reactions and trapped as ATP.
16 Why is ATP called the energy currency of the cell? ATP stores energy released during respiration and supplies it when needed.
17 What is the role of carbon skeletons produced during respiration? They act as precursors for biosynthesis of other molecules.
18 Do plants require oxygen for respiration? Yes, plants require oxygen and also release carbon dioxide.
19 Which structures help gaseous exchange in plants? Stomata and lenticels help gaseous exchange.
20 Why do plants not need specialised respiratory organs? Each plant part manages its own gas exchange and plants have low gas exchange demands.
21 Why is oxygen not a problem in photosynthesising cells? Oxygen is released within the cell during photosynthesis.
22 How are living cells arranged in thick stems? Living cells occur in thin layers inside and beneath the bark.
23 What are lenticels? Lenticels are openings in stems that help gaseous exchange.
24 What is the role of dead interior cells in stems? They mainly provide mechanical support.
25 How do parenchyma cells help gaseous exchange? Loose packing of parenchyma cells creates interconnected air spaces.
26 What are the end products of complete combustion of glucose? Carbon dioxide, water, and energy.
27 Why is glucose oxidised in several small steps in respiration? To couple released energy with ATP synthesis instead of losing it as heat.
28 What are the products released during respiration? Carbon dioxide, water, and energy are released.
29 What are facultative anaerobes? Organisms that can survive with or without oxygen.
30 What are obligate anaerobes? Organisms that require anaerobic conditions.
31 What is glycolysis? Glycolysis is the breakdown of glucose to pyruvic acid without the help of oxygen.
32 Who proposed the scheme of glycolysis? Gustav Embden, Otto Meyerhof, and J. Parnas.
33 What is another name for glycolysis? The EMP pathway.
34 Where does glycolysis occur? Glycolysis occurs in the cytoplasm.
35 What is the end product of glycolysis? Two molecules of pyruvic acid are formed.
36 Why is the diffusion distance for gases small even in large plants? Each living cell in a plant is located quite close to the surface of the plant.
37 Where are living cells located in thick woody stems? They are organised in thin layers inside and beneath the bark.
38 What are lenticels? Lenticels are openings in stems that help gaseous exchange.
39 What is the role of cells in the interior of stems? Interior cells are dead and provide mechanical support.
40 How do parenchyma cells help in gaseous exchange? Loose packing of parenchyma cells provides an interconnected network of air spaces.
41 What are the end products of complete combustion of glucose? Carbon dioxide, water, and energy.
42 Why is glucose oxidised in several small steps during respiration? So that released energy can be coupled with ATP synthesis instead of being lost as heat.
43 What are the products released during respiration? Carbon dioxide, water, and energy.
44 Why do some organisms perform respiration without oxygen? Some organisms are adapted to anaerobic conditions where oxygen is unavailable.
45 What are facultative anaerobes? Organisms that can survive with or without oxygen.
46 What are obligate anaerobes? Organisms that require anaerobic conditions.
47 What is glycolysis? Glycolysis is the breakdown of glucose to pyruvic acid without the help of oxygen.
48 Who proposed the scheme of glycolysis? Gustav Embden, Otto Meyerhof, and J. Parnas.
49 What is another name for glycolysis? EMP pathway.
50 In which organisms is glycolysis the only process in respiration? In anaerobic organisms.
51 Where does glycolysis occur? Glycolysis occurs in the cytoplasm of the cell.
52 What is the end product of glycolysis? Two molecules of pyruvic acid.
53 In plants, glucose for glycolysis is derived from which substances? From sucrose or storage carbohydrates.
54 Which enzyme converts sucrose into glucose and fructose? Invertase.
55 Which enzyme converts glucose and fructose into glucose-6-phosphate? Hexokinase.
56 Into what does glucose-6-phosphate isomerise? Fructose-6-phosphate.
57 How many reactions occur in glycolysis? Ten enzyme-controlled reactions.
58 At which two steps is ATP utilised in glycolysis? During conversion of glucose to glucose-6-phosphate and fructose-6-phosphate to fructose-1,6-bisphosphate.
59 Into which compounds does fructose-1,6-bisphosphate split? Dihydroxyacetone phosphate and 3-phosphoglyceraldehyde (PGAL).
60 During which step is NADH + H+ formed in glycolysis? During conversion of PGAL to 1,3-bisphosphoglycerate (BPGA).
61 What happens to PGAL during formation of BPGA? PGAL is oxidised and combines with inorganic phosphate.
62 During which conversion is ATP synthesised from BPGA? During conversion of BPGA to 3-phosphoglyceric acid (PGA).
63 Another ATP molecule is synthesised during conversion of which compound to pyruvic acid? Phosphoenolpyruvate (PEP).
64 What is the key product of glycolysis? Pyruvic acid.
65 On what does the metabolic fate of pyruvate depend? It depends on the cellular need.
66 What are the three major pathways in which cells handle pyruvic acid? Lactic acid fermentation, alcoholic fermentation, and aerobic respiration.
67 Under what conditions does fermentation occur? Fermentation occurs under anaerobic conditions.
68 In which organisms does fermentation commonly occur? In many prokaryotes and unicellular eukaryotes.
69 Which enzymes catalyse alcoholic fermentation? Pyruvic acid decarboxylase and alcohol dehydrogenase.
70 Which organisms produce lactic acid from pyruvic acid? Lactic Acid Bacteria (LAB)
71 What happens in animal muscles during vigorous exercise? Pyruvic acid is reduced to lactic acid when oxygen is inadequate.
72 Which enzyme converts pyruvic acid into lactic acid in muscles? Lactate dehydrogenase.
73 How much energy is released during fermentation? Less than seven per cent of the energy in glucose is released.
74 Why are fermentation processes considered hazardous? Because acid or alcohol is produced.
75 At what alcohol concentration do yeasts poison themselves to death? About 13 per cent alcohol concentration.
76 Where does aerobic respiration occur in eukaryotes? Within the mitochondria.
77 Which type of respiration is most common in higher organisms? Aerobic respiration.
78 What happens to pyruvate before aerobic respiration? It is transported from the cytoplasm into the mitochondria.
79 What is the second crucial event in aerobic respiration? Electrons removed from hydrogen atoms are passed to molecular oxygen with simultaneous ATP synthesis.
80 Where does complete oxidation of pyruvate occur? In the mitochondrial matrix.
81 Where is the electron transfer process located in mitochondria? On the inner mitochondrial membrane.
82 What happens to pyruvate in the mitochondrial matrix? It undergoes oxidative decarboxylation.
83 Which enzyme catalyses oxidative decarboxylation of pyruvate? Pyruvic dehydrogenase.
84 How many NADH molecules are produced from two pyruvic acid molecules? Two molecules of NADH.
85 With which reaction does the TCA cycle begin? Condensation of acetyl group with oxaloacetic acid (OAA) and water to form citric acid.
86 Which enzyme catalyses formation of citric acid in the TCA cycle? Citrate synthase.
87 What happens to citrate after its formation in the TCA cycle? It is isomerised to isocitrate.
88 What is formed after α-ketoglutaric acid in the citric acid cycle? Succinyl-CoA is formed.
89 What happens to succinyl-CoA in the remaining steps of the citric acid cycle? It is oxidised to oxaloacetic acid (OAA).
90 Which molecule is synthesised during conversion of succinyl-CoA to succinic acid? GTP is synthesised.
91 What type of phosphorylation occurs during synthesis of GTP in the TCA cycle? Substrate-level phosphorylation.
92 How is ATP synthesised from GTP in the TCA cycle? GTP is converted to GDP with simultaneous synthesis of ATP from ADP.
93 Why is replenishment of oxaloacetic acid necessary in the TCA cycle? Because oxaloacetic acid is the first member of the cycle required for continued oxidation of acetyl CoA.
94 How many ATP molecules are directly synthesised in the TCA cycle? Two ATP molecules.
95 What is the Electron Transport System (ETS)? ETS is the metabolic pathway through which electrons pass from one carrier to another.
96 Where is the Electron Transport System located? In the inner mitochondrial membrane.
97 Which enzyme oxidises NADH in the ETS? NADH dehydrogenase (Complex I).
98 To which molecule are electrons transferred from Complex I? Ubiquinone.
99 What is the reduced form of ubiquinone called? Ubiquinol.
100 What is the role of cytochrome c in ETS? It acts as a mobile carrier transferring electrons between Complex III and IV.
101 Where is cytochrome c located? On the outer surface of the inner mitochondrial membrane.
102 What does Complex IV refer to? Cytochrome c oxidase complex.
103 Which metal centres are present in Complex IV? Two copper centres.
104 Which complex is responsible for ATP synthesis in ETS? ATP synthase (Complex V).
105 What substrates are used by ATP synthase to form ATP? ADP and inorganic phosphate.
106 How many ATP molecules are produced from oxidation of one NADH molecule? Three ATP molecules.
107 What is the role of oxygen in aerobic respiration? Oxygen acts as the final hydrogen acceptor.
108 Why is oxygen essential for aerobic respiration? It removes hydrogen from the system and drives the whole process.
109 Why is ATP formation during respiration called oxidative phosphorylation? Because energy from oxidation-reduction reactions is utilised for phosphorylation.
110 Which complex helps in ATP synthesis during respiration? ATP synthase (Complex V).
111 Along which gradient do protons move during ATP synthesis? Along the electrochemical proton gradient.
112 Why is calculation of ATP gain from glucose considered theoretical? Because it is based on assumptions that are not fully valid in living systems.
113 What is the first assumption made while calculating net ATP gain? A sequential and orderly pathway functions with glycolysis, TCA cycle, and ETS following one after another.
114 What assumption is made regarding NADH produced during glycolysis? It is transferred into mitochondria and undergoes oxidative phosphorylation.
115 What assumption is made about intermediates of the respiratory pathway? None of the intermediates are used to synthesise any other compound.
116 What assumption is made regarding respiratory substrates? Only glucose is respired and no alternative substrates enter the pathway.
117 Why are the assumptions of ATP calculation not completely valid in living systems? Because all pathways work simultaneously and substrates are continuously added or withdrawn.
118 How are enzymatic rates controlled in living systems? By multiple means.
119 What is the net gain of ATP molecules during aerobic respiration of one glucose molecule? 38 ATP molecules.
120 What is the net ATP gain during fermentation of one glucose molecule? Two ATP molecules.
121 How is oxidation of NADH different in fermentation and aerobic respiration? NADH is oxidised slowly in fermentation but vigorously in aerobic respiration.
122 Which substrate is favoured for respiration? Glucose.
123 What happens to carbohydrates before entering respiration? They are first converted into glucose.
124 Into which compounds are fats broken before respiration? Glycerol and fatty acids.
125 Into what is glycerol converted before entering the respiratory pathway? PGAL (phosphoglyceraldehyde).
126 Into what are fatty acids degraded before entering respiration? Acetyl CoA.
127 Which enzymes degrade proteins during respiration? Proteases.
128 What happens to amino acids before entering the respiratory pathway? They undergo deamination.
129 Why was respiration traditionally considered a catabolic process? Because it involves breakdown of substrates.
130 Why is the respiratory pathway called amphibolic? Because it is involved in both catabolism and anabolism.
131 How are fatty acid synthesis and respiration interconnected? Acetyl CoA can enter respiration during breakdown or be withdrawn for fatty acid synthesis.
132 What is catabolism? Breakdown processes within a living organism.
133 What is anabolism? Synthesis processes within a living organism.
134 What is another name for respiratory quotient? Respiratory ratio.
135 On what does the respiratory quotient depend? The type of respiratory substrate used during respiration.
136 What is the RQ value when carbohydrates are completely oxidised? RQ = 1.
137 What is the RQ value when fats are used as respiratory substrates? Less than 1.
138 Which fatty acid example is given for RQ calculation? Tripalmitin.
139 What is the RQ value of tripalmitin? Approximately 0.7.
140 What is the approximate RQ value when proteins are respiratory substrates? About 0.9.
141 Are pure proteins or fats generally used alone as respiratory substrates in living organisms? No, respiratory substrates are often more than one.
142 Which structures allow gaseous exchange in plants? Stomata and lenticels.
143 How does gaseous exchange occur in plants? By diffusion.
144 What is cellular respiration? Breaking of C - C bonds of complex organic molecules by oxidation to release energy.
145 Which substrate is favoured for respiration? Glucose.
146 Can fats and proteins be used to yield energy during respiration? Yes, they can also be broken down to yield energy.
147 Where does the initial stage of cellular respiration occur? In the cytoplasm.
148 Into what is each glucose molecule broken during glycolysis? Two molecules of pyruvic acid.
149 What determines the fate of pyruvate? Availability of oxygen and the organism.
150 Which two types of fermentation occur under anaerobic conditions? Lactic acid fermentation and alcohol fermentation.
151 In which organisms does fermentation commonly occur? Many prokaryotes, unicellular eukaryotes, and germinating seeds.
152 When does aerobic respiration occur in eukaryotic organisms? In the presence of oxygen.
153 Through which system is ATP synthesis accomplished in mitochondria? Electron Transport System (ETS).
154 Where is the Electron Transport System located? On the inner membrane of mitochondria.
155 What is oxidative phosphorylation? ATP synthesis using energy released during movement of electrons through ETS.
156 Into what is oxygen reduced during oxidative phosphorylation? Water.
157 Why is the respiratory pathway called amphibolic? Because it involves both anabolism and catabolism.
158 Where is the Electron Transport System (ETS) located? On the inner membrane of mitochondria.
159 What happens to electrons as they move through the ETS? They release energy that is trapped to synthesise ATP.
160 What is the process of ATP synthesis through ETS called? Oxidative phosphorylation.
161 Why is the respiratory pathway called amphibolic? Because it involves both anabolism and catabolism.
162 On what does the respiratory quotient depend? The type of respiratory substance used during respiration.
163 Differentiate between respiration and combustion. Respiration is a step-wise enzyme-controlled oxidation process in living cells, while combustion is rapid oxidation releasing energy as heat.
164 Differentiate between aerobic respiration and fermentation. Aerobic respiration completely oxidises glucose in the presence of oxygen, while fermentation causes partial breakdown under anaerobic conditions.
165 What are respiratory substrates? Substances oxidised during respiration to release energy.
166 Which is the most common respiratory substrate? Glucose.
167 What is glycolysis? Glycolysis is the breakdown of glucose into pyruvic acid in the cytoplasm.
168 What is ETS? ETS is a metabolic pathway through which electrons pass from one carrier to another in the inner mitochondrial membrane.
169 Differentiate between aerobic and anaerobic respiration. Aerobic respiration occurs in the presence of oxygen, while anaerobic respiration occurs without oxygen.
170 Differentiate between glycolysis and fermentation. Glycolysis converts glucose into pyruvate, while fermentation converts pyruvate into alcohol or lactic acid under anaerobic conditions.
171 Differentiate between glycolysis and citric acid cycle. Glycolysis occurs in cytoplasm and forms pyruvate, whereas citric acid cycle occurs in mitochondria and oxidises acetyl CoA.
172 What assumptions are made while calculating net ATP gain? Sequential functioning of pathways, transfer of NADH into mitochondria, no withdrawal of intermediates, and only glucose acting as substrate.
173 Why is the respiratory pathway considered amphibolic? Because respiratory intermediates participate in both breakdown and synthesis processes.
174 What is the RQ value for fats? Less than 1 (approximately 0.7).
175 What is oxidative phosphorylation? ATP synthesis using energy released during electron transport in ETS.
176 What is the significance of step-wise release of energy in respiration? It helps trap energy efficiently in ATP instead of losing it as heat.