Respiration: Life Processes

What is the process of acquiring oxygen from outside the body and using it to break down food for cellular needs called?

• Transportation

• Excretion

• Respiration

• Nutrition

72. What is the first step in the breakdown of glucose in all organisms?

• Conversion to ethanol
• Breakdown into pyruvate in the cytoplasm
• Breakdown in the mitochondria
• Conversion to lactic acid

Answer explanation

"In all cases, the first step is the break-down of glucose, a six-carbon molecule, into a three-carbon molecule called pyruvate. This process takes place in the cytoplasm".

73. What is the end product of glucose breakdown in yeast during fermentation (anaerobic respiration)?

• Lactic acid and energy
• Carbon dioxide, water, and energy
• Ethanol, carbon dioxide, and energy
• Pyruvate and energy

Answer explanation

"This process takes place in yeast during fermentation... the pyruvate may be converted into ethanol and carbon dioxide".

74. Where does the breakdown of pyruvate using oxygen (aerobic respiration) take place?

• Cytoplasm
• Mitochondria
• Muscle cells
• Yeast

Answer explanation

"Break-down of pyruvate using oxygen takes place in the mitochondria".

75. What are the products of aerobic respiration?

• Ethanol and carbon dioxide
• Lactic acid
• Carbon dioxide and water
• Pyruvate

Answer explanation

Aerobic respiration "breaks up the three-carbon pyruvate molecule to give three molecules of carbon dioxide. The other product is water".

76. What causes cramps in our muscles during sudden activity?

• The build-up of ethanol
• The build-up of lactic acid due to a lack of oxygen
• The build-up of carbon dioxide
• The breakdown of ATP

Answer explanation

"This build-up of lactic acid in our muscles during sudden activity causes cramps". This happens when there is a lack of oxygen.

77. What is the "energy currency" for most cellular processes?

• Glucose
• ADP
• ATP
• Pyruvate

Answer explanation

"ATP is the energy currency for most cellular processes".

78. Why is the rate of breathing in aquatic organisms much faster than in terrestrial organisms?

• They are more active
• Water is heavier than air
• The amount of dissolved oxygen in water is much lower than the amount of oxygen in the air
• They have smaller lungs

Answer explanation

"Since the amount of dissolved oxygen is fairly low compared to the amount of oxygen in the air, the rate of breathing in aquatic organisms is much faster".

79. In humans, what filters the air passing through the nostrils?

• Rings of cartilage
• Fine hairs and mucus
• The diaphragm
• The alveoli

Answer explanation

"The air passing through the nostrils is filtered by fine hairs that line the passage. The passage is also lined with mucus which helps in this process".

80. What is the primary respiratory pigment in human beings that transports oxygen?

• Chlorophyll
• Haemoglobin
• Myoglobin
• Cytochrome

Answer explanation

"In human beings, the respiratory pigment is haemoglobin which has a very high affinity for oxygen".