Gas Exchange

Question 1

Define breathing

Answer 1

Movement of air in and out of the body

Question 2

Define respiration

Answer 2

Chemical reaction to release the energy in the form of ATP

Question 3

Define gas exchange

Answer 3

Diffusion of oxygen from the air In the alveoli into the blood and carbon dioxide from the blood into the air in the alveoli

Question 4

What is the structure of the human gas exchange

Answer 4

-air is pulled into the lungs through the trachea
-the trachea divides into 2 bronchi and further divides into bronchioles and terminate in millions of sacs the aveoli

Question 5

How do humans ventilate

Answer 5

-the external and internal intercostal muscles work in antagonistic pairs
-antagonistic means when one muscle contracts another relaxes
-the external intercostal muscles contract causing Rib cage to move upwards and air to move in diagram flattered pressure in thoracic cavity decrease which is inspiration
-the internal intercostal muscles contract pulling the the rib cage in diaphragm relax causing air to flow out, pressure in thoracic cavity increases which is expiration

Question 6

What happens in the external intercostal muscles during inspiration(inhalation) and expiration(exhalation)

Answer 6

Inspiration
-contracts moves the Ribs up
Expiration
-relax move ribs down

Question 7

What happens in the internal internalcostal muscles during inspiration(inhalation) and expiration(exhalation

Answer 7

Inspiration
-they relax
Expiration
-contract to pull the ribs in

Question 8

What happens in diaphragm during inspiration (inhalation) and expiration (exhalation)

Answer 8

Inspiration
Contracts and flattens
Expiration
-relaxes and moves up

Question 9

What happens to the lung volume in inspiration(inhalation) and expiration (exhalation)

Answer 9

Inspiration
-increases
Expiration
-decreases

Question 10

What happens to the pressure in thoracic cavity in inspiration(inhalation ) and expiration(exhalation

Answer 10

Inspiration
- decreases
Expiration
-increases

Question 11

What happens to the movement of air inspiration(inhalation) and expiration (exhalation)

Answer 11

Inspiration
-into the lungs
Expiration
-out of the lungs

Question 12

Define pulmonary ventilation

Answer 12

Is the total volume of air that is moved into the lugs during one min(d

Question 13

What is the equation of pulmonary ventilation

Answer 13

Tidal volume (dm3) x ventilation rate ( min-1)

Question 14

What is the essential features in the alveolar epithelium as a surface of which gas exchange takes place

Answer 14

-lots alveoli and they are tiny sacs which gives a large surface area to volume ratio for gas exchange
-alveoli epithelium cells is very thin so shorter diffusion pathway
-alveolus is surrounded by a network of capillaries to remove exchanged gases and maintain a concentration gradient

Question 15

Insects don’t have lungs but they do have a tracheal system for gas exchange
Explain how they do this

Answer 15

-they have spiracles along their thorax and they have valves to allow O2 and CO2 to diffuse in and out down the concentration gradient
-the trachea has tubes full of air so fast diffusion rate
-tranches divides into tracheoles which have thin walls to create a short diffusion pathway
- loads of trancheoles gives a large surface area
-use of oxygen and production carbon dioxide sets up a steep diffusion gradient

Question 16

How are insects adapted to prevent water loss

Answer 16

-spiracles have valves which can close to prevent water being lost via evaporation
-insects use their spiracle valves to balance water loss and gas exchange
Insects have a Waterproof exoskeleton

Question 17

What are the adaptations of gills in the fish

Answer 17

-gills are made up of stacks of gill filaments covered in gill lamellae giving a large surface area to volume ratio
-thin lamellae gives it a short diffusion pathway
-concentration gradient is maintenance by a counter current mechanism

Question 18

What is the countercurrent flow mechanism

Answer 18

Water flows over the gills In the opposite direction to the flow of blood in the capillaries

Question 19

Describe gas exchange in the stomata

Answer 19

-oxygen diffuse out of the stomata and CO2 diffuses in the stomata
-gases diffuse due to concentration gradient between inside and outside the leaf
-stomata closes at night to reduce water loss as photosynthesis isn’t happening

Question 20

Describe gas exchange in the mesophyll

Answer 20

-has large moist surfaces to absorb oxygen and carbon dioxide ,facilitating diffusion
-air spaces between cells to allow gases to diffuse - faster diffusion rate
-concentration gradient formed as gases are absorbed or released
Large surface area

Question 21

What is a xerophytes

Answer 21

They’re plants that grow in dry areas and adapted to survive with limited water

Question 22

How is xerophyte adapted to minimise water loss

Answer 22

-sunken stomata to trap moisture to increase local humidity
- curled leaves to trap moisture to increase local humidity
-hairs to reduce leaf surface area and to trap moisture
-longer root network to reach more water
-thicker cuticle to reduce evaporation

Question 23

Describe and explain the mechanism of which lungs to fill with air

Answer 23

-diagram contracts and external intercostal muscles contract
-cause volume to increase and pressure decrease
-air moves down a pressure gradient

Question 24

Explain how the counter current mechanism in fish gills ensures the maximum amount of the oxygen passes into the blood flowing through the gills.

Answer 24

-water and blood flows in opposite directions
-blood is always passing water with a higher oxygen concentration-as oxygen concentration is higher in water
-diffusion gradient is maintained through the entire length of the gill lamellae

Question 25

Describe why death of alveolar epithelium cells reduce gas exchange in human lungs

Answer 25

-reduced surface area
-increased/longer diffusion distance
-reduced rate of gas exchange

Question 26

What are the advantages of a counter current mechanism in gas exchange accross gills

Answer 26

-water and blood flow in opposite directions
-maintains diffusion gradient along the entire length of lamellae
-maintains concentration gradient of oxygen as oxygen concentration is higher in the water

Question 27

Why do plants with little water grow slowly

Answer 27

-stomata will be closed
-less co2 uptake for photosynthesis and glucose production

Question 28

Describe how oxygen is taken from the alveolus to the blood

Answer 28

-across alveolar epithelium
-into epithelium of capillary

Question 29

Describe the gross structure of the human gas exchange system and how we breathe in and out

Answer 29

-air is pulled into the lungs via trachea
-divides into 2 bronchi and further divides into bronchioles
-which have tiny sacs of alveoli
-Breathing in causes diaphragm contracts and external intercostal muscles contract;
-Causes volume increase and pressure decrease in thoracic cavity
-Breathing out -cause Diaphragm relaxes and internal intercostal muscles contract
-6. Causes volume decrease and pressure increase in thoracic cavity