Chapter 8 Respiration in Humans II

Question 1

Name the precess which produces carbon dioxide in the body [1] (2017/A6)

Answer 1

Aerobic respiration

Question 2

Explain why oxygen used increases as excersise level increases. [4] (2012/B8)

Answer 2

1. As the level of exercise increases, muscular contraction increases [1]
2. The energy demand of muscles increases [1].
3. To meet this energy demand, muscles undergo a higher rate of aerobic respiration [1] ,
4. where oxygen is used to oxidize glucose to release energy. As a result, the amount of oxygen used increase as the level of exercise increases [1].

Question 3

Describe the similarities and differences between aerobic and anaerobic respiration [5] (2016/B10 E)

Answer 3

Similarities: [2]
1. Both aerobic and anaerobic respiration release energy for cellular activities. [1]
2. Both aerobic and anaerobic respiration involves breakdown of glucose/ use glucose as a substrate. [1]
Differences:
1. Aerobic respiration involves the use of oxygen while anaerobic respiration does not involve oxygen. [1]
2. Aerobic respiration releases large amount of energy while anaerobic respiration releases small amount of energy. [1]
3. Aerobic respiration produces carbon dioxide and water while anaerobic respiration produces lactic acid. [1]
4. Aerobic respiration takes place in the mitochondria but anaerobic respiration takes place in the cytoplasm. [1]

Question 4

State the circumstances under which anaerobic respiration occurs in humans and the effects of the process on muscle cells. [5] (2016/B10 E)

Answer 4

1. When humans perform vigorous exercises like a sprint where there is vigorous muscular contractions with increased energy demand, [1]
2. The maximum rate of aerobic respiration in the muscle cells is unable to release energy fast enough to meet the high energy demands and also, the rate at which oxygen is absorbed is not fast enough to meet high demand for faster rate of aerobic respiration. [1]
3. As a result, muscle cells will carry out anaerobic respiration to release energy and supplement its energy needs. [1]
4. During anaereobic respiration, glucose is broken down into lactic acid and accumulates in the muscles cells causing lactic acid build-up resulting in muscle fatigue. [1]
5. This means muscles can only sustain anaerobic respiration for a short period of time and the muscle cells will not be able to continue to contract and relax until the lactic acid is removed by the blood. [1]

[5] Need to recognise the conditions for anaerobic respiration between supply and demand of energy

Question 5

Write the word equation for aerobic respiration (self)

Answer 5

Glucose + oxygen –> Carbon Dioxide + Water + Large amount of energy released

Question 6

Write the chemical equation for aerobic respiration (self)

Answer 6

C6H12O6 + 6O2 —> 6CO2 + 6H2O + Energy

Question 7

Write the word equation for anaerobic respiration in yeast (self)

Answer 7

Glucose —> Ethanol + Carbon Dioxide + Energy

Question 8

Write the chemical equation for anaerobic respiration in yeast (self)

Answer 8

C6H12O6⟶2C2H5OH + 2CO2+ Energy

Question 9

Write the word equation for anaerobic respiration in humans (self)

Answer 9

Glucose —> Lactic acid + Small amount of energy released

Question 10

Write the chemical equation for anaerobic respiration in humans (self)

Answer 10

C6H12O6 -> 2C3H6O3

Question 11

Respiration VS Photosynthesis [5 points] (self)

Answer 11

• In respiration, energy is released while Energy is stored in photosynthesis.
• Oxygen is used and carbon dioxide and water is given of during respiration, but Carbon dioxide and water is used and oxygen is given off during photosynthesis
• Respiration is a catabolic process, resulting in the breakdown of carbohydrate molecules while photosynthesis is a anabolic process, resulting in the building up of carbohydrate molecules.
• Respiration occurs in all cells independent of chlorophyll and sunlight while photosynthesis occurs only in cells containing chlorophyll on the prescence of sunlight.
• Respiration results in a loss of dry mass while photosynthesis results in gain of dry mass.

Question 12

Name the path the air takes entering the nostril to the alveoli [8 points] (self)

Answer 12

1. Nostril
2. Nasal passage
3. Pharynx
4. Larynx
5. Trachea
6. Bronchi
7. Bronchioles
8. Cluster of alveoli

Question 13

Name the two types of cells lining the trachea [2] (self)

Answer 13

1. Gland cells
2. Ciliated cells

Question 14

State the function of the gland cells of the epithelium of the trachea

Answer 14

Secrete mucus to trap dust particles and bacteria