Respiration Flashcards
The graph below shows how level of exercise changes the risk of death in young and old people.
Use the information in the graph to describe the effect of level of exercise on the percentage risk of death. (3)
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As the level of exercise increases, the percentage risk of death decreases for both old and young people (1). From 20-70a.u., the percentage risk of death for young people is lower than old people (1). Comparing 20a.u. to 70a.u., there is a larger decrease for older people (1) (difference = 53%) than younger people (difference = 27%).
Exercise has an effect on the risk of having coronary heart disease (CHD). In people with CHD the heart muscle cells receive less oxygen.
Describe how heart muscle cells make ATP when less oxygen is available. (6)
[2015/01 WBI05/01]
When less oxygen is available, ATP is made via anaerobic respiration (1). Glycolysis (1) occurs in the cytoplasm, and it does not require oxygen to initiate. Glucose is phosphorylated (1) and it is then split into two TP molecules and the hydrogen is transferred to the NAD to form NADH (1). Each TP molecule is then converted into pyruvate acid (1) which creates 4 ATP molecules (2 ATP molecules are generated after glycolysis). To continue generating ATP molecules, NAD needs to be reformed, which can be done by reducing pyruvate acid using NADH (1) which converts into lactate (1) and produces NAD.
State the effect of exercise on each of the following.
(i) The risk of having diabetes and being obese. (1)
(ii) The immune system. (1)
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(i) exercising decreases the risk (1) of diabetes and obesity
(ii) high intensity exercising reduces immunity (1)
A person will suffer a pain called angina if heart muscle cells receive less oxygen.
Suggest how lack of oxygen in heart muscle cells can cause angina. (2)
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Since a lack of oxygen means that anaerobic respiration is occurring, lactate (1) is produced which is acidic and can cause fatigue to heart muscle cells by denaturing the enzymes (1).
The electron transport chain is involved in the synthesis of ATP.
The diagram below shows part of the electron transport chain.
Name the molecules P, Q and R. (3)
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P - NAD (1)
Q - oxygen (1)
R - water (1)
Place a cross in the box next to the description of where the electron transport chain occurs. (1)
A cytoplasm surrounding mitochondria B inner mitochondrial membrane C mitochondrial matrix D outer mitochondrial membrane
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B (inner mitochondrial membrane) (1)
In 2013, poachers killed over 80 elephants in Zimbabwe by poisoning their drinking water with cyanide. Cyanide inhibits cytochrome oxidase, the last carrier in the electron transport chain.
Suggest how inhibiting cytochrome oxidase would kill an elephant. (4)
[2015/01 WBI05/01]
By inhibiting cytochrome oxidase, it means that an electron pair cannot be donated to an oxygen molecule (1). This means that oxidative phosphorylation (1) would no longer occur, and ATP would not form (1) again since the electron transport chain stops (1). This would kill an elephant as ATP would only be generated from glycolysis (1), which is not enough to support the energy required for the daily needs of an elephant such as contracting the cardiac muscles (1) to pump blood around the elephant’s body.
Place a cross in the box next to the part of a mitochondrion where most ATP synthesis takes place. (1)
A inner mitochondrial membrane B intermembrane space C matrix D outer mitochondrial membrane
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A (inner mitochondrial membrane) (1)
Nucleic acid is involved in the synthesis of proteins in mitochondria. These proteins are needed to make ATP.
Place a cross in the box that shows the nucleic acid found in mitochondria. (1)
A DNA only B RNA only C DNA and RNA D neither DNA or RNA
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C (DNA and RNA) (1)
Place a cross in the box next to the part of the mitochondrion in which protein synthesis takes place. (1)
A cristae B intermembrane space C ribosomes D stalked particles
C (ribosomes) (1)
Place a cross in the box next to the name of the structure labelled Q in the electronmicrograph. (1)
A Golgi apparatus B lysosomes C rough endoplasmic reticulum D smooth endoplasmic reticulum
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D (smooth endoplasmic reticulum) (1)
The Krebs cycle and chemiosmosis take place in mitochondria.
Explain how chemiosmosis and the production of ATP will be affected if the Krebs cycle is inhibited. (5)
[2017/01 WBI05/01]
If the Krebs cycle is inhibited, there would be no chemiosmosis (1) as oxidative phosphorylation in the electron transport chain would not occur since NADH would not be produced in the Krebs cycle (1). This means that as NADH would not be oxidised by the first protein in the electron transport chain and hence would not pass along the electron transport chain. This means that no protons would be accumulated in the matrix and it would not diffuse (1) into the intermembrane space (1) down the concentration (1) and electrochemical gradient through stalked particles (1) that work with ATP synthase. This means that ATP would not be produced (1) as there would be no energy to allow ADP to combine with an inorganic phosphate.
