Chapter 10 - Respiration In Humans

Question 1

Define respiration.

Answer 1

Respiration is the oxidation of food molecules with the release of energy in living cells.

Question 2

Why do living things respire?

Answer 2

Energy is needed for organisms to sustain life. The energy needed for organisms to move, grow, excrete and reproduced is obtained through the consumption of food. To use the energy available in food, living things is needed to breakdown food molecules through oxidation.

Question 3

What is aerobic respiration? (Function/Definition)

Answer 3

It is the breakdown of food molecules in the presence of oxygen. Large amount of energy is released, and carbon dioxide and water are released as waste products.

Question 4

What is the overall equation for aerobic respiration?

Answer 4

C6H12O6+6 O2 –> 6 CO2+6 H2O+ (38 ATP) energy

Question 5

How is energy released?

Answer 5

Energy is released when a phosphate bond is broken. Adenosine triphosphate (ATP) is converted to Adenosine diphosphate (ADP).

Question 6

Name 3 examples of energy consuming processes in living things.

Answer 6

1) transmission of nerve impulses
2) cell division
3) muscular contractions like heartbeats and respiratory movements

Question 7

How does respiring keep one warm?

Answer 7

Some energy is released as heat during respiration. the heat energy is circulated around your body by blood to keep one warm.

Question 8

What is anaerobic respiration? (def/func)

Answer 8

It is the breakdown of food molecules in the ABSENCE of oxygen, releasing lesser energy than aerobic respiration.

Question 9

Anaerobic respiration is mainly used by microorganisms that live in areas where there is little or no oxygen. But why does organisms that respire aerobically respire anaerobically too? Give 3 examples.

Answer 9

They respire anaerobically when there is insufficient oxygen. For yeast, they cannot be very active under this condition.

1) yeast (alcoholic fermentation)
2) human muscle
3) alcohol

Question 10

What is the chemical equation for anaerobic respiration in HUMANS?

Answer 10

C6H12O6 –> 2 C3H6O3 (lactic acid) + (2ATP) energy

Question 11

What is the chemical equation for anaerobic respiration in YEAST?

Answer 11

C6H12O6 —> 2 C2H5OH (ethanol) + 2 CO2 + Energy (small amount because glucose is partially broken down&ethanol still contains energy)

Question 12

What happens during exercise and why?

Answer 12

During increased vigorous muscular contractions, there is an increase in energy demand. Respiration increases as more oxygen and glucose is transported in the blood for muscles cells to undergo aerobic respiration to release energy to muscles. Heartbeat and rate of breathing increases to remove carbon dioxide and take in oxygen at a faster rate, so as to meet the energy demand. The limit to the increase of breathing rate causes the maximum aerobic respiration to be unable to meet oxygen demands. An oxygen debt is incurred, and anaerobic respiration takes place to provide the energy required, resulting in the accumulation of lactic acid in muscle cells, causing fatigue and muscular pain. The body then needs to rest and recover. Muscles feel pain due to the toxic lactic acid.

Question 13

After vigorous exercise, the breathing rate continues to be high for some time. Why is this so? (2)

Answer 13

1) restore oxygen in lungs.
2) to repay oxgen debt: Oxygen is needed to oxidise lactic acid and release energy in liver, which is used to convert lactic acid to glucose.

Question 14

Why do athletes obtain most energy through anaerobic respiration instead of aerobic respiration during a sprint?

Answer 14

Within the short period of time, the oxygen supply to the muscles is insufficient for aerobic respiration to meet energy needs.

Question 15

Define oxygen debt.

Answer 15

It is the amount of oxygen required to oxidise the lactic acid produced during anaerobic respiration.

Question 16

How is oxygen debt removed?

Answer 16

During rest, remove lactic acid from muscle and transport to liver as it is toxic. Some of the lactic acid in the liver is oxidized to release energy. This energy is used to convert remaining lactic acid to glucose. The glucose is then transported back to the muscle.

Question 17

Describe an experiment that proves that carbon dioxide is a product of respiration for human. (4)

Answer 17

1) prepare four flask (from left to right: KOH solution, limewater, snails, limewater, then connected to suction pump)
2) KOH removes CO2 from the air entering flask containing limewater.
3) limewater further checks for the presence of CO2 and it should not turn chalky.
4) air entering flask containing snails does not contain CO2. Thus, any CO2 detected in the last flask would be due to respiration by snails.

Question 18

Describe an experiment that proves that carbon dioxide is a product of anaerobic respiration for yeast. (4)

Answer 18

1) 2 testubes are connected. (Left to right: glucose and yeast suspension, limewater)
2) the glucose is boiled and cooled to remove oxygen.
3) due to the limited oxygen, yeast undergoes anaerobic respiration.
4) the limewater turns chalky as carbon dioxide is released.

Question 19

Describe an experiment that proves that heat is a product of respiration. (6)

Answer 19

1) soak pea seeds in water and add in dilute antiseptic solution to prevent growth of microorganisms as they can respire and produce heat.
2) when germination begins, place seeds in a vacuum flask so as to prevent heat from escaping and entering the area.
3) insert a thermometer and surround its bulb completely with wet germinating seeds.
4) support the thermometer with cotton wool. Cotton wool plug is porous and thus allows gaseous exchange between seeds and environment.
5) invert the flask to allow direct contact of thermometer and seeds, recording a more accurate temperature, and fewer seeds are needed.
6) there is a rise in temperature. Respiration gives off heat energy.

Question 20

Why do we need a respiratory system?

Answer 20

Humans are multicellular and complex. We have a small surface area to volume ratio. Thus, a special system of organs is needed for gaseous exchange between environment and cells in our bodies.

Question 21

What are the benefits of breathing through the nose? (3)

Answer 21

1) fringe of hair and mucous layer on the walls of the nasal passage Trap dust and foreign particles.
2) air is warmed and moistened as air passes through.
3) harmful chemicals may be detected by small sensory cells in the mucous membrane.

Question 22

What is an adaption of the trachea?

Answer 22

It is supported by a C-shaped rings of cartilage (firm, elastic, flexible connective tissue), which ensures that the trachea is always open.

Question 23

What does the membrane next to the lumen of the trachea contain?(2)

Answer 23

1) gland cells

2) ciliated cells

Question 24

What is the function of the gland cells?

Answer 24

Secrete mucus that trap dust particles and bacteria in the air channelled into the lungs.

Question 25

What is the function of the ciliated cells?

Answer 25

Contain hair-like structures called CILIA that sweeps the trapped particles and bacteria UP the bronchi and trachea, into the pharynx.

Question 26

What does the trachea branch out to and end in?

Answer 26

The trachea divides into two bronchi, which carries air into the lungs. Bronchi divide rapidly to form bronchioles, which end in clusters of alveoli.

Question 27

What is the function of alveoli?

Answer 27

Sites of gaseous exchange between air and blood

Question 28

What is the adaptation of alveoli? (4)

Answer 28

1) Numerous alveoli increases the surface area for gaseous exchange of oxygen and carbon dioxide via diffusion.
2) walls of alveolus is one-cell thick to provide shorter diffusion distance for faster rate of gaseous exchange of oxygen and carbon dioxide via diffusion.
3) lined with thin film of moisture to allow oxygen to dissolve before diffusing into blood.
4) WALLS of alveoli are richly supplied with blood capillaries to maintain the concentration gradient for efficient gaseous exchange of oxygen and carbon dioxide via diffusion.

Question 29

What should you do for respiration in humans?

Answer 29

READ TEXTBOOK!!!! (Set as 3)

Question 30

How is the oxygen and carbon dioxide concentration gradients between alvelolar air and blood maintained? (2)

Answer 30

1) continuous flow of blood through blood capillaries

2) movement of air in and out of alveoli caused by breathing

Question 31

How is carbon dioxide removed from lungs?(6)

Answer 31

1) tissue cells produce a large amount of CO2 during aerobic respiration.
2) as blood passes through these tissues via blood capillaries, CO2 diffuses into the blood and enters the red blood cells.
3) CO2 then reacts with water in the red blood cells to form carbonic acid. This reaction is catalysed by the enzyme carbonic anhydrase which is present in red blood cells.
4) the carbonic acid is then converted into hydrogencarbonate atoms (HCO3-), which diffuses out of the red blood cells. Hence, most carbon dioxide is carried as HCO3- ions in blood plasma. A small amount of CO2 is also carried and dissolved in the red blood cells.
5) in the lungs, HCO3- ions diffuse back into the red blood cells where they are converted into carbonic acid, then into water and CO2.
6) the CO2 then diffuses out of the blood capillaries and into the alveoli, where it is expelled during expiration.

Question 32

define breathing.

Answer 32

It is part of the gas exchange process. It refers to the muscular contractions and movements of the ribs, which result in air moving in and out of the lungs.

Question 33

What is the function of the sternum?(chest bone)

Answer 33

For ribs to be attached to it.

Question 34

What is the function of the intercostal muscles?

Answer 34

Move the ribcage up and down during breathing.

Question 35

Define diaphragm(function).

Answer 35

It is a dome-shaped sheet of muscle and elastic tissue that contracts and relaxes to change the volume of the thoracic cavity.

Question 36

What is the path of air into lungs?(8)

Answer 36

1) external nostrils
2) nasal passages
3) pharynx
4) larynx
5) trachea
6) bronchi
7) bronchioles
8) alveoli

Question 37

What happens during inspiration?(6)

Answer 37

1) ribs move upwards and outwards
2) external intercostal muscles contract, internal intercostal muscles relax
3) diaphragm MUSCLES contract and flattens.
4) volume of thoracic cavity increases
5) lung expands and pressure decreases.
6) atmospheric pressure higher than lungs, FORCES air into lungs.

Question 38

What happens during expiration?(6)

Answer 38

1) ribs move downwards and inwards
2) external intercostal muscles relax, internal intercostal muscles contract
3) diaphragm MUSCLES relaxes and arches upwards.
4) volume of thoracic cavity decreases.
5) lungs compress and pressure increases.
6) atmospheric pressure is lower than lungs; thus air is forced out of the lungs.

Question 39

What are the 4 major toxic components of tobacco smoke?

Answer 39

1) nicotine
2) carbon monoxide
3) irritants (hydrogen cyanide, formaldehyde)
4) tar

Question 40

What are the functions of nicotine? (3)

Answer 40

1) addictive
2) increase risk of blood clots in blood vessels
3) increases heartbeat and blood pressure

Question 41

What are the functions of carbon monoxide? (3)

Answer 41

1) binds with haemoglobin irreversibly, forming carboxyhaemoglobin, thus reducing the oxygen carrying capacity of blood. Less oxygen is transported to other parts of the body. It reduces respiration by body tissues, reducing energy released.
2) increases rate at which fats are deposited on the inner arterial walls
3) damage lining of blood vessels, increases risk of artherosclerosis and blood clotting in arteries (cause of coronary heart disease)

Question 42

What are the functions of irritants in tobacco smoke? (2)

Answer 42

1) paralyse cilia lining in air passages

2) increase risk of chronic bronchitis and emphysema

Question 43

What are the functions of tar? (3)

Answer 43

1) uncontrollable cell division:carcinogenic, increase
risk of lung cancer
2) paralyses the cilia lining in air passages, dust particles trapped in mucus lining in air passages cannot be removed, increasing risks of chronic bronchitis and emphysema
3) reduces efficiency of gaseous exchange

Question 44

What happens when a person has chronic bronchitis? (3)

Answer 44

1) epithelium lining in airways is inflamed (infected)
2) excessive mucus secretion
3) cilia lining in airways is paralysed.

Question 45

What are the symptoms of chronic bronchitis?(2)

Answer 45

1) breathing difficulties due to blocked airways

2) persistent coughing (body’s response to clear blocked airways)

Question 46

What happens when a person has emphysema? (2)

Answer 46

1) partition walls of alveoli break down due to violent coughs, reducing surface area available for gaseous exchange
2) lungs lose elasticity and become inflated with air

Question 47

what are the 2 symptoms of emphysema?

Answer 47

1) wheezing

2) breathing difficulties

Question 48

What is passive smoking?

Answer 48

It is the inhalation of 2nd hand smoke, causing the same diseases as smoking.

Question 49

What is the stimulus for breathing?

Answer 49

High concentration of carbon dioxide in the blood or alveoli air. When there is too little carbon dioxide in the lungs, breathing movements do not occur.

Question 50

What is the model of breathing mechanism? Describe.

Answer 50

Bell jar. The jar is sealed tight to create a vacuum like the chest cavity. When the rubber sheet (diaphragm) is pulled downwards, the balloons expand and suck in air from the atmosphere due to the difference in pressure.

Question 51

What is a limitation of the bell jar representation of the thoracic cavity?

Answer 51

Inability of ribcage to move in expanding the thoracic cavity

Question 52

How does the increase in rate of blood flow during exercise advantage?

Answer 52

It allows more oxygen to be supplied to muscles, allowing increased rate of respiration to allow greater release of energy.