12. Energy and respiration
A section of Biology, 9700
Listing 10 of 192 questions
The humpback whale, Megaptera novaeangliae, is one of the world’s largest aquatic mammals. It can grow to a length of up to 15 metres and a mass of up to 36 000 kg. A large proportion of the mass of a humpback whale is a very thick layer of fat-filled cells stored under the skin, called blubber. The humpback whales are seasonal feeders. They feed in polar regions during the summer and then migrate to warmer temperate and tropical waters to mate and have their young during the polar winter. One reason that the humpback whale has managed to reach its enormous size is because it is a member of a simple food web. is an example of such a food web. humpback whale krill (small crustaceans) herring phytoplankton (very small photosynthetic organisms) not drawn to scale The humpback whale is a carnivore, feeding on krill and herring. The herring feed on krill. Add arrow heads to the lines drawn on to show the direction of energy flow in the food web. State the trophic level to which the humpback whale belongs. In terms of energy transfer, explain how the humpback whale is able to reach such a large size. The thickness of blubber in humpback whales decreases during the non-feeding season and increases during the feeding season. Suggest explanations for this observation. Describe the roles of water as an environment for organisms, such as those shown in .
9700_w12_qp_22
THEORY
2012
Paper 2, Variant 2
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Complete the following passage about ATP by writing in the missing words. All living organisms use energy. The most common immediate source of energy is adenosine triphosphate (ATP) which is used in every cell for the movement of ions against a concentration gradient, known as . ATP is known as the universal currency of energy. ATP is a phosphorylated nucleotide which is known as a ‘high energy’ molecule. It is made of an organic base, adenine, a 5 carbon sugar named and three phosphate groups. ATP is very soluble in and easily transported within the cell. The removal of the outer phosphate group by the process of releases energy. The energy released as a result of this reaction can be channelled directly into other reactions in the cell. A certain proportion of this energy is lost as . ATP is continually broken down and is reformed at a fast rate by the process of respiration. During a sporting event an athlete may have to carry out anaerobic respiration in addition to aerobic respiration to produce sufficient ATP. outlines both processes in a muscle cell and shows how a liver cell is linked to these processes. Liver cell Muscle cell glucose additional oxygen blood lactate blood glucose glucose lactate glycolysis ATP pyruvate link reaction acetyl coA Krebs cycle carbon dioxide oxidative phosphorylation ATP water You may refer to in answering questions to below. Glucose produced in the liver cell can be released into the blood to maintain blood glucose concentration. State one use of glucose within the liver cell. Suggest why anaerobic respiration is said to be less efficient than aerobic respiration. Complete the table to indicate, within the muscle cell, the precise locations of glycolysis, the link reaction, the Krebs cycle and oxidative phosphorylation. process precise location glycolysis link reaction Krebs cycle oxidative phosphorylation Glucose is phosphorylated at the start of glycolysis in the muscle cell. Suggest why this phosphorylated glucose does not diffuse out of the cell into the surrounding tissue fluid. Additional oxygen is required in the metabolic pathways involved in the conversion of lactate to glucose. State the term given to this additional oxygen.
9700_s11_qp_41
THEORY
2011
Paper 4, Variant 1
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All organisms respire. The ATP produced as a result of respiration is used as the energy currency of the cell. Outline two examples of movement in cells that use ATP. ATP cannot be stored in cells so it has to be continually re-synthesised to meet the demands of an organism. A person with a total quantity of 0.2 moles of ATP needs to hydrolyse 150 moles of ATP per day. Calculate how many times the total quantity of 0.2 moles of ATP has to be re-synthesised per hour to meet the demand of 150 moles per day. Show your working and give your answer to the nearest whole number. answer = Name the stages in which chemiosmosis occurs in respiration and in photosynthesis. respiration photosynthesis Fur seals are mammals that are adapted to live in cold temperatures. Fur seals have large quantities of a type of fat tissue known as brown adipose tissue. Brown adipose cells contain many mitochondria. These mitochondria contain a transport protein called thermogenin. shows the role of thermogenin in a mitochondrion of a brown adipose cell when external temperatures are cold. H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ H+ thermogenin heat ATP synthase electron transport chain inner mitochondrial membrane matrix intermembrane space ADP + Pi ATP With reference to , describe and explain the effect of thermogenin on ATP synthesis. When the external temperature is warm, thermogenin cannot function. When the external temperature becomes cold, thermogenin is able to function as a result of cell signalling: • adrenaline is released • adrenaline acts on brown adipose cells • a sequence of events is triggered that results in the activation of the enzyme lipase • lipase hydrolyses triglycerides in the cells into fatty acids • fatty acids enter the mitochondrion • thermogenin starts to function. Outline the stages of cell signalling that trigger the functioning of thermogenin.
9700_s21_qp_42
THEORY
2021
Paper 4, Variant 2
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Questions Discovered
192