2 g Gas exchange

Question 1

Define Diffusion

Answer 1

Random movement of molecules from a region of high concentration to the lower

Question 2

Name the exchange surfaces

Answer 2

Humans-lungs Fish-gills Leaves & roots-plants

Question 3

How is efficiency of exchange increased in these organs

Answer 3

• large surface area
• Short diffusion distance
• Well ventilation (animals)

Question 4

What do respiration and photosynthesis both have in common

Answer 4

Rely on exchange of oxygen and carbon dioxide

Question 5

Why is the concentration of oxygen always low inside the respiring cells

Answer 5

The cells use oxygen to respire

Question 6

Equation for photosynthesis

Answer 6

6 CO₂ + 6 H₂O + light –> C₆H₁₂O₆ + 6 O₂

Question 7

Why is the concentration of CO₂ always low inside photosynthesising cells

Answer 7

The cells use CO₂

Question 8

What are the 3 key gases in gas exchange (plants)

Answer 8

-CO₂ - released in resp. used in phot.
-O₂ - released in phot. used in resp.
-H₂O - Released in resp. used in phot

Question 9

Adaptations of the leaf to gas exchange

Answer 9

-Thin- Short diffusion distance
-Flat- Large surface area to volume ratio
-Many stomata- allow movement in & out of leaf allowing steep concentration gradient

Question 10

Adaptations of internal leaf structures

Answer 10

-Air spaces- allow gas movement around mesophyll cells
-Thin cell walls- Allow gases to move more easily
-Moist air- Dissolve easier
-Close contact between cells and air spaces- allows efficient gas exchange

Question 11

Where are stomata

Answer 11

Between two guard cells on the lower epidermis

Question 12

When do stomata open

Answer 12

When water moves into the guard cell or when theres sunlight (turgid)

Question 13

When do stomata close

Answer 13

When theres low water or sunlight (flaccid)

Question 14

Why do the stomata close

Answer 14

To prevent any diffusion in or out of the leaf

Question 15

Meaning of turgid

Answer 15

Filled with water via osmoisis (hypotonic)

Question 16

Meaning of flaccid

Answer 16

Lacking water (isotonic)

Question 17

What gas has net movement into the plant during the night

Answer 17

Oxygen

Question 18

What gas has net movement out of the plant during the day

Answer 18

Carbon dioxide

Question 19

What gas exchange happens during the day

Answer 19

Respiration and photosynthesis (Photo. > resp.)

Question 20

What gas exchange happens during the night

Answer 20

Respiration only

Question 21

What gas exchange happens in low light intensity

Answer 21

Respiration and photosynthesis (Photo. = resp.)

Question 22

What gas has net movement into the plant in low light intensity

Answer 22

No net movement

Question 23

Adaptations for gas exchange in the lungs

Answer 23

-Large surface area
-Thin walls- short diffusion distance
-Good ventilation with air- steep diffusion gradient
-Good blood supply

Question 24

Function of ribs

Answer 24

Protect the organs

Question 25

Function of intercostal muscles

Answer 25

Control of the movement of thorax during inhalation and exhalation

Question 26

Function of Diaphragm

Answer 26

Helps change the volume of thorax to allow inhalation and exhalation

Question 27

Function of trachea

Answer 27

Windpipe that connects the mouth to the lungs

Question 28

Function of Larynx

Answer 28

Allows to make a sound when air passes across

Question 29

Function of bronchi

Answer 29

2 large tubes branching of trachea

Question 30

Function of Bronchioles

Answer 30

Bronchi split into smaller tubes that connect to the alveoli

Question 31

Function of alveoli

Answer 31

Air sacs where gas exchange takes place

Question 32

Function of plural cavity

Answer 32

Fluid that reduces friction to allow lungs to move freely

Question 33

What do the tiny hairs on cillia cells do

Answer 33

Push mucus up to the passages towards the nose and throat so it can be removed

Question 34

What does the mucus do

Answer 34

Trap particles, pathogens like bacteria, viruses, dust and prevents them from getting into the lungs

Question 35

Function of the external I.M

Answer 35

pull the rib cage up

Question 36

What happens during inhalation (steps)

Answer 36

-Diaphragm contract (flattens) -External I.M contract (pull the ribs out) -Increase of volume of the thorax -Decrease in air pressure inside the lungs -Air is drawn in

Question 37

What happens during exhalation (steps)

Answer 37

-Diaphragm relaxes (goes back to the domed shape) -E.I.M relax so the ribs drop -Decrease in the volume of the thorax -Increase in air pressure Air forced out

Question 38

What are the chemicals in cigarettes (3)

Answer 38

-Tar- a carcinogen -Nicotine- addictive substance & narrows blood vessels -Carbon monoxide- Reduces the oxygen-carrying capacity of blood

Question 38

What happens during forced exhalation

Answer 38

The internal I.M will pull the ribs down more quickly (during activity there's an increased level of CO2 in the blood)

Question 39

Effects of nicotine

Answer 39

-Narrows blood vessels (increased blood pressure) -Increases heart rate -Can lead to heart attacks or strokes

Question 40

Effects of Carbon monoxide

Answer 40

-Binds irreversibly to haemoglobin -Increases breathing frequency and depth need to increase -Puts strain on the circulatory system to pump blood faster

Question 41

Effects of tar

Answer 41

-Carcinogen -Contributes to COPD -Causes chronic bronchitis (smokers cough, destroys cillia & mucus) -Develops emphysema

Question 42

Effects of emphysema

Answer 42

Frequent infections, which causes enzymes to be released -Alveoli becomes less elastic and cannot stretch so it bursts -Reduces surface area for gas exchange -Patients are breathless and wheezy