Respiration + Gas Excahnge

Question 1

Aerobic respiration word equation

Answer 1

Glucose + oxygen —> carbon dioxide + water (+energy)

Question 2

Aerobic respiration symbol equation

Answer 2

C6H12O6 + 6O2 —> 6CO2 + 6H2O

Question 3

Anaerobic respiration word equation

Answer 3

Glucose —> lactic acid (+energy)

Question 4

Anaerobic respiration in plants word equation

Answer 4

Glucose —> ethanol + carbon dioxide (+energy)

Question 5

Difference between anaerobic and aerobic respiration

Answer 5

Aerobic is with oxygen, anaerobic is without

Question 6

What indicator detects CO2

Answer 6

Hydrogen-carbonate indicator

Question 7

Hydrogen colour indicator colours

Answer 7

High CO2 = yellow
Atmospheric CO2 = orange
Low CO2 = purple

Question 8

What three things to plants need to grow

Answer 8

Water
Oxygen
Warmth

Question 9

What is gas exchange

Answer 9

Happens via diffusion
CO2 moves into the leaf
O2 (waste product from photosynthesis) moved out of the leaf via stomata
(High —> low concentration)

Question 10

What affects the net exchange of gases

Answer 10

Light intensity
(Photosynthesis only happens in the day - but plants must respire all the time)

Question 11

Gas exchange during the day

Answer 11

More light intensity
Plants make more O2 via photo to use in respiration
Release O2
Take in CO2

Question 12

Gas exchange during the night

Answer 12

Low light intensity
Only respire
No photosynthesis
Take in O2
Release CO2

Question 13

How are leaves adapted for efficient gas exchange

Answer 13

• broad - large SA for diffusion
• thin - shirt diffusion distance
• air spaces inside the leaf - increases SA and allows gases to travel easily between cells
• stomata - let gases diffuse in and out and water escape (transpiration)

Question 14

Stomata opening and closing

Answer 14

Close in the dark - no photosynthesis so no need for CO2 to be let in, when closed less water can escape so plant won’t dry out
Close when roots dry up to stop the plant photosynthesis or drying out and dying
Opening and closing is controlled by guard cells

Question 15

What happens when inhaling

Answer 15

Intercostal muscles and diaphragm contract
Thorax volume increases, decreasing pressure, drawing air in

Question 16

What happens when exhaling

Answer 16

Intercostal muscles and diaphragm relax
Thorax volume decreases, forcing air out

Question 17

Where does gas exchange occur in humans

Answer 17

Alveoli

Question 18

Process of gas exchange in humans

Answer 18

1. Lungs contain millions of alveoli
2. Blood next to alveoli has just returned from lungs (oxygenated)
3. Oxygen diffuses out of the alveoli (high conc) into blood (low conc)
4. CO2 diffuses out of blood (high conc) into alveolus (low conc)
5. When blood reaches body cells oxygen is released from RBCs (high conc) and diffuses into body cells (low conc)
6. At the same time, CO2 diffuses out of body cells into blood and is carried back to lungs

Question 19

How are alveoli specialised for gas exchange

Answer 19

• many alveoli - high SA
• moist lining for gases to dissolve in
• thin walls (one cell thick) - short distance for diffusion
• good blood supply - maintain high conc gradient
• permeable walls - gases can diffuse across easily