gas exchange

Question 1

why can singled-celled organisms survive using diffusion alone?

Answer 1

• higher surface area to volume ratio
• substances can diffuse in and out at a high rate and reach all parts of the cells

Question 2

reasons for exchange system

Answer 2

• larger multicellular organisms have smaller surface area to volume ration
• cell in the center would not receive any materials if rely on diffusion alone

Question 3

gas exchange surface is improved by…

Answer 3

1) ventilation mechanism
2) blood circulatory system
3) haem protein

Question 4

ventilation mechanism

Answer 4

pumping mechanism that helps move respiratory medium into or out of lungs/gills (maintain concentration gradient)

Question 5

blood circulatory system

Answer 5

speeding up transport of oxygen as soon as it’s diffused in (maintain concentration gradient)

Question 6

haem protein

Answer 6

• haemoglobin
• associate with oxygen to increase gas-carrying ability of blood

Question 7

gas exchange surface

Answer 7

1) permeable surface area
2) thin (quicker diffusion)
3) large surface area (diffusion at the same time)
4) good supply of oxygen

Question 8

why is lungs located at the thoracic cavity

Answer 8

contains small quantity of fluid which allows for friction-free movement

Question 9

location of the lungs

Answer 9

thoracic cavity

Question 10

ciliated epithelium

Answer 10

• single layer of cells covered with cilia
• sweep mucus towards mouth (dust and bacteria doesn’t reach lungs)

Question 11

use of cartilage in walls of bronchi and trachea

Answer 11

provides support and prevents tube from collapsing when air pressure is low

Question 12

characteristics of trachea

Answer 12

• c- shaped ring of cartilage (incomplete)

Question 13

characteristic of bronchiole

Answer 13

• no cartilage
• smooth muscle

Question 14

characteristic of bronchi

Answer 14

• irregular and incomplete rings of cartilage
• smooth muscle

Question 15

characteristic of alveolus

Answer 15

• no smooth muscle

Question 16

goblet cells

Answer 16

• found in ciliated epithelium
• secretes mucus (traps dust and bacteria)

Question 17

mucus

Answer 17

slimy solution of mucin composed of glycoproteins with many carbohydrate chains that make them sticky and trap particles

Question 18

what happens when chemical pollutants such as sulfur dioxide and nitrogen dioxide dissolve in mucus

Answer 18

form an acidic solution which can irritate lining of airway

Question 19

gas exchange surface

Answer 19

alveoli

Question 20

cells of alveoli

Answer 20

squamous epithelium and elastic fiber

Question 21

elastic fibers

Answer 21

• when inhale, fibers stretch —> alveoli and airways expand
• when exhale, fibers recoil —> reduce volume of alveoli and expel air out of lungs

Question 22

squamous epithelium

Answer 22

• consisted of thin-flattened cells
• minimize distance for diffusion
• control flow of air to and from aveoli

Question 23

distribution of cells/tissues in trachea and bronchus

Answer 23

1) cartilage
2) ciliated epithelium
3) goblet cells
5) smooth muscle
6) elastic fibres

Question 24

distribution of cells/tissues in alveoli

Answer 24

1) elastic fibres

Question 25

features of efficient gas exchange

Answer 25

1) large surface area 2) thin layers (short diffusion distance) 3) blood supply (good blood supply to maintain a large diffusion gradient) 4) ventilation (maintains diffusion gradient)

Question 26

adaptions of the alveolus

Answer 26

1) thin cells: short diffusion pathway, increasing diffusion rate 2) large surface area: increase rate of diffusion 3) moist walls: allows gases to dissolve (pass through cell membrane) and increasing diffusion rate