Respiration in Plants Module

Q1. What does the term “cellular respiration” refer to?

1. Water decomposition,
2. The breakdown of air to release energy,
3. Food items decomposing to produce energy,
4. Energy is released as soil breaks down.

Answer- Option (3) is correct.
Explanation: Cellular respiration is the process by which food components are broken down inside of a cell to produce energy, which is then captured to create ATP. Eukaryotes, which include all multicellular creatures and some single-celled species, generate energy through aerobic respiration. The most potent electron acceptor found in nature, oxygen, is used in aerobic respiration. Eukaryotes’ complex life functions and busy lives are made possible by the incredibly efficient mechanism of aerobic respiration. However, it also implies that they need a steady supply of oxygen to survive; otherwise, they won’t be able to produce the necessary energy. Other, less effective modes of respiration can be used by prokaryotic species like bacteria and archaebacteria. Because they don’t need oxygen, they can survive in situations where eukaryotic species could not.

Q2. Which of the following can synthesize their food?

1. Yellow Plants
2. Green vegetation
3. Animals
4. Mycoplasma

Answer- Option (2) is correct.
Explanation: Only cyanobacteria and green plants can prepare their food through the process of photosynthesis. They capture light energy, transform it into chemical energy, and then store it in the bonds of carbohydrates. The fossil fuels (coal, oil, and gas) that drive our industrial society were created by energy derived from photosynthesis carried out by plants millions of years ago. Green plants and other tiny animals that fed on plants grew more rapidly than they were eaten in earlier times, and as a result, their remnants were deposited in the Earth’s crust through geological processes such as sedimentation.

Q3. Which of the following acts as a precursor for the production of other molecules?

1. Phosphorous substrate;
2. Nitrogen substrates;
3. Carbon substrates;
4. Sulphur substrates.

Answer- Option (3) is correct.
Explanation: Carbon skeletons serve as building blocks for the biosynthesis of other biomolecules since their oxidation results in the production of ATP, which is then stored by cells and used by organisms for a variety of energy-demanding functions.

Q4. How come plants can survive without having specialist breathing organs?

1. It would incur additional costs.
2. They dislike it.
3. Each plant component tends to its own demands
4. All the components of the plants have easy access to oxygen.

Answer- Option (3) is correct.
Explanation: There are a number of reasons why plants can survive without respiratory systems.

• Each component of the plant takes care of its own gas-exchange requirements.
• Plants do not provide significant gas exchange requirements.
• Gases must disperse across a relatively small area.

Q5. Which of the following structures are used by plants to exchange gases?

1. Stem,
2. Root,
3. Bark,
4. Stomata.

Answer- Option (4) is correct.
Explanation: In contrast to mammals, plants do not have specialist organs for gaseous exchange; instead, they employ stomata and lenticels to do this. Plants can live without any specialist respiratory organs with ease. Multiple microscopic holes can be seen close to a leaf when they are studied under a microscope. Stomata refers to both the grouping of these holes and to a single pore itself. You need to be aware of the meaning of stomata. Although they can be found on other plant components like a stem, these tiny apertures are typically found in the epidermal layer of leaves. The passage of gases like oxygen and carbon dioxide, which are necessary for photosynthesis, is facilitated by stomata.

Q6. How do lenticels work?

1. Holes in the bark’s outer layer
2. Cracks on the outside of roots
3. Leaves’ pores
4. Stem pores

Answer- Option (1) is correct.
Explanation: Living cells are arranged inside and below the bark of stems in thin layers. In addition, they have what are known as lenticels. The interior’s dead cells serve only as a mechanical support system.

Q7. What is the plants’ method for oxidizing glucose?

1. Oxidize glucose in a series of large steps
2. Oxidise glucose in a series of little steps
3. Decrease glucose in multiple significant stages.
4. Lower glucose levels gradually.

Answer- Option (2) is correct.
Explanation: The glucose molecule is catabolized by the plant cell so that some of the energy released does not escape as heat. The secret is to oxidize glucose in a series of modest stages rather than all at once.

Q8. Which of these cannot assist us in identifying C3 from C4 plants?

1. The acceptor molecule for carbon dioxide,
2. The Kranz anatomy is present,
3. Photorespiration,
4. The number of chloroplasts.

Answer- Option (4) is correct.
Explanation: C4 plants differ from C3 plants in a number of ways. They demonstrate Kranz anatomy. While C4 plants exhibit Kranz anatomy and have a low rate of photorespiration, C3 plants do not. The number of chloroplasts depends on the leaves of the plant and does not differ in C3 and C4 plants. As long as a plant uses the C3 pathway during the dark reaction of photosynthesis, it is referred to as a C3 plant. The leaves of these plants do not reveal anything about Kranz’s anatomy. These plants only engage in photosynthesis while their stomata are open. The majority of shrubs, trees, and plants are C3 vegetation (around 95%). In contrast, C4 plants are those that employ the C4 pathway during the dark response. These plants have dimorphic chloroplasts, and in contrast to C3 plants, C4 plants have kranz anatomy in their leaves. Approximately 5% of all plants on Earth are C4 species.

Q9. What does the name RuBisCO suggest?

1. Its active site can bind to oxygen and carbon dioxide.
2. It causes the synthesis of carbon dioxide and oxygen.
3. In order to break down sugar, it utilizes carbon and oxygen.
4. It decomposes RuBP using carbon and oxygen.

Answer- Option (1) is correct.
Explanation: The most prevalent enzyme in the world is called RuBisCO, or ribulose-1,5-bisphosphate carboxylase oxygenase. Both oxygen and carbon dioxide can be bound by RuBisCO’s active site. It has a stronger sensitivity to carbon dioxide. Mesophyll cells in C3 plants and bundle sheath cells in C4 plants both contain RuBisCO. The chemical ribulose bisphosphate (RuBP) has five carbons. It serves as the Calvin cycle’s main carbon dioxide acceptor and is transformed into two molecules of 3-PGA (3-phosphoglyceric acid) by RuBisCO. As implied by its name, RuBisCO exhibits both oxygenase and carboxylase activity. RuBP undergoes a process known as photorespiration in which molecular oxygen serves as the substrate, converting it to one phosphoglycerate and one phosphoglycolate molecule.

Q10. Why do C4 plants have higher production than C3 plants?

1. C4 plants exhibit Kranz anatomy.
2. Photorespiration is absent in C4 plants
3. High phosphoglycerate formation is observed in C4 plants.
4. High phosphoglycolate generation is evident in C4 plants.

Answer- Option (2) is correct.
Explanation: The production of C4 plants is higher than that of C3 plants since they don’t have photorespiration. Contrary to C3 plants, C4 plants do not exhibit phosphoglycerate and phosphoglycolate production. Additionally, C4 plants lessen the negative effects of the photorespiration cycle on production by raising the concentration of CO2 collected in this method. Because there is less need to seal stomata and because the C4 pathway is not necessary, C3 plants are more productive at low temperatures.

Q 11. Which of these is produced by photorespiration?

1. NADPH;
2. ATP;
3. CO2;
4. Sugars.

Answer- Option (3) is correct.
Explanation: During photorespiration, oxygen is bound by the active site of RuBisCO. Instead of being created, ATP is used. There is no synthesis of carbohydrates or NADPH. As a result of this process, carbon dioxide is emitted. High temperatures and light intensity both have an impact on photorespiration, boosting the production of glycolate and the flow via the photorespiratory pathway. The synthesis and metabolism of a tiny particle called glycolate are linked to photorespiration, which results in the light-dependent uptake of oxygen and elimination of carbon dioxide.

Q 12. When lactic acid and alcohol are fermented, how much energy is released?

1. Less than 7%,
2. More than 7%,
3. More than 50%, or
4. More than 75%

Answer- Option (1) is correct.
Explanation: Less than 7% of the energy in glucose is released during lactic acid and alcohol fermentation, and not all of it is bound in ATP’s high energy bonds. The anaerobic environment, which is devoid of oxygen, and the presence of helpful bacteria that obtain energy from fermentation are all necessary conditions for the fermentation process to take place. If there is enough sugar, certain yeast cells (Saccharomyces cerevisiae) will choose fermentation over aerobic respiration even when there is abundant oxygen.

Q 13. What causes a decline in carbon dioxide fixing in certain C3 plants?

1. Formation of phosphoglycerates,
2. The absence of RuBP,
3. RuBisCO binds oxygen,
4. RuBP binds oxygen.

Answer- Option (3) is correct.
Explanation: The active site of RuBisCO can bind to both oxygen and carbon dioxide, which is why the answer is c. As the active site of RuBisCO cannot bind to carbon dioxide when oxygen attaches to it, carbon dioxide fixation is diminished.

Q14. Which of these occurs in the first phase of the Calvin pathway?

1. Three molecules of 2PGA are created,
2. CO2 and RuBisCO combine to make,
3. RuBP and CO2 mix to form PGA,
4. RuBP serves as an activator.

Answer- Option (3) is correct.
Explanation: The carbon dioxide fixation phase is the first stage of the Calvin cycle or pathway. Two molecules of 3PGA are produced when the carbon dioxide acceptor molecule RuBP interacts with carbon dioxide.

Q 15. What element controls the binding of CO2 to the RuBisCO active site?

1. Sunlight intensity
2. Chloroplast count
3. Closing and opening of stomata.
4. Relative oxygen and carbon dioxide concentrations

Answer- Option (4) is correct.
Explanation: Oxygen and carbon dioxide can both attach to RuBisCO’s active site. With carbon dioxide, it is more affine. Because of this, the binding of carbon dioxide depends on the relative amounts of oxygen and carbon dioxide.