Gas exchange in humans & Respiration

Question 1

Features of gas exchange surface area in humans:

Answer 1

large surface area
thin surface
good blood supply
good ventilation with air

Question 2

Oxygen percentage in inspired air

Answer 2

21%

Question 3

oxygen percentage in expired hair

Answer 3

16%

Question 4

CO2 percentage inspired air

Answer 4

0.04%

Question 5

CO2 percentage in expired air

Answer 5

4%

Question 6

Expired air contains less oxygen because

Answer 6

oxygen is used up by the cells in the body

Question 7

Expired air contains more

Answer 7

carbon dioxide because it is a waste product of respiration. It contains more water vapour
because the water from the lining of the windpipe evaporate and is expired.

Question 8

Function of cartilage is

Answer 8

keep the airway/ trachea open
prevent collapse
protects (named) airways ;
allows (free flow of) air into (the lungs) ;
allows flexibility / can breathe even when, bent / swallowing / AW ;
reduces resistance to movement of air ;
sound production in larynx ;
forms incomplete rings around, trachea / bronchi ;

Question 9

During inspiration

Answer 9

rib cage moves upwards and outwards, diaphragm contract,
external intercostal muscles contract, internal intercostal muscles relax, volume of
thorax increase, pressure in thorax decrease, air move into the lungs to equalize the
pressure.

Question 10

During expiration

Answer 10

rib cage moves downwards and inwards, diaphragm relax,
external intercostal muscles relax, internal intercostal muscles contract, volume of
thorax decrease, pressure in thorax increase, air move out the lungs to equalize the
pressure.

Question 11

As physical activity increase breathing rate increase because

Answer 11

muscles contract
more. Muscles require more energy. More aerobic respiration takes place. More
carbon dioxide is produced, pH of blood decrease because carbon dioxide is acidic.
This is detected by the brain, brain send impulses to breathing muscles like heart
and diaphragm to contract more frequently and more hardly. This leads to an
increased rate and greater depth of breathing.

Question 12

Goblet cells produce

Answer 12

mucus

Question 13

Mucus

Answer 13

sticky substance which traps pathogens
and dust particles and prevent them from entering the lungs. Ciliated cells beat and
move the mucus up towards the throat where it can be sneezed out of the body.

Question 14

Uses of energy in living organism:

Answer 14

muscle contraction
protein synthesis
cell division
active transport
growth
the passage of nerve impulses
the maintenance of a constant body temperature

Question 15

Aerobic respiration

Answer 15

the chemical reactions in cells that use oxygen to break down
nutrient molecules to release energy. glucose + oxygen → carbon dioxide + water

Question 16

aerobic respiration reaction

Answer 16

C6H12O6 + 6O2 -> 6CO2 +6H20

Question 17

Anaerobic respiration

Answer 17

chemical reactions in cells that break down nutrient
molecules to release energy without using oxygen

Question 18

Word equation for anaerobic respiration in yeast

Answer 18

glucose → alcohol(ethanol) +
carbon dioxide

Question 19

the chemical equation for anaerobic respiration

Answer 19

C6H12O6 -> 2C2H5OH + 2CO2

Question 20

Word equation for anaerobic respiration in muscles during vigorous exercise as

Answer 20

glucose → lactic acid

Question 21

Lactic acid builds up in muscles and blood during vigorous exercise causing

Answer 21

oxygen debt

Question 22

To remove oxygen debt after exercise:

Answer 22

fast heart rate continues to transport lactic acid in the blood from the muscles to
the liver.
deeper and faster breathing continues to supply oxygen for the aerobic
respiration of lactic acid.
aerobic respiration of lactic acid in the liver.