Chapter 6 - Exchange

Question 1

Describe expiration

Answer 1

• The diaphragm relaxes
• The external intercostal muscles relax
• decreasing the volume of the thorax
• increasing the pressure
• air is forced out, down the conc grad

Question 2

How does gaseous exchange take place in insects?

Answer 2

1) air enters through the spiracles
2) O2 diffuses along the trachea down the conc grad
3) the trachea are surrounded by respiring cells into which O2 diffuses.

Question 3

What is the equation for pulmonary ventilation?

Answer 3

PV = Tidal Volume x Breathing/ Ventilation rate

Question 4

Exopeptidases

Answer 4

Hydrolyses peptide bonds AT THE END of the polypeptide

Question 5

How are the lungs adapted for efficient gas exchange? (Diffusion distance)

Answer 5

Both the alveoli and capillaries have thin epithelium ( 1 cell thick)
Creating a short diffusion pathway

Question 6

How are leaves adapted for efficient gaseous exchange?

Answer 6

Only a few cells thick so short diffusion distance

Mesophyll air spaces increase surface area for fast diffusion

Question 7

How do gases enter and leave the spongy mesophyll in plants?

Answer 7

Diffusion

Question 8

What is tidal volume?

Answer 8

Volume of air in or out per breath at rest.

Question 9

How does emphysema affect the lungs and how is it caused?

Answer 9

• caused by pollution or smoking
• alveoli are broken down, decreasing the surface area/ rate of diffusion
• loss of elastin, lungs don’t recoil as well which reduces the conc. grad.

Question 10

What kind of reaction breaks down the glycosidic bonds?

Answer 10

Hydrolysis reactions

Question 11

How do the stomata help to conserve water?

Answer 11

When cells have a lot of water they remain turgid, and so turgid guard cells keep the stomata open.

When cells have less water the cell becomes flaccid, flaccid guard cells close the stomata.

Question 12

Endopeptidases

Answer 12

Hydrolyse peptide bonds WITHIN a polypeptide chain

Question 13

What does lung disease result in?

Answer 13

• Decreased rate of diffusion
• feeling weak/ tired
• decreased SA increased diffusion pathway
• decreased conc grad
• less O2 in blood so less ATP + respiration

Question 14

What is the affect of asthma on the lungs?

Answer 14

• Asthma is an allergic reaction
• causing the bronchioles to secrete mucus
• narrowing airways
• reducing the amount of ventilation
• decreasing the conc grad

Question 15

Describe how a xerophyte may be adapted for its environment.

Answer 15

1) thick waxy cuticle decreases evaporation
2) stomata are in curled leaves - which results in a build up of water vapour, decreasing the water vapour gradient.
3) deep roots

Question 16

Where is the enzyme Amylase made?

Answer 16

Saliva glands and pancreas

Question 17

What is digestion?

Answer 17

The process by which large biological molecules are HYDROLYSED into smaller molecules to pass across cell membranes.

Question 18

How is water loss limited in insects?

Answer 18

Limited by the ability to close spiracles and the waxy cuticle.

Question 19

Where is maltase made?

Answer 19

The small intestine

Question 20

How is a lipid digested?

Answer 20

1) the lipid droplet is emulsified by bile salts, which increases the
SA.
2) Lipase enzyme breaks down lipid droplets into micelles made up of monoglycerides. These are fat soluble, and so can diffuse across the cell membrane.

Question 21

What is a xerophyte?

Answer 21

A plant adapted for dry conditions such as a succulent or cactus.

Question 22

What is ventilation rate?

Answer 22

Number of breaths per minute

Question 23

Describe the gas exchange system in fish

Answer 23

• filaments and lamellae increase SA
• there is a short diffusion distance because of thin epithelium
• counter current flow maintains the conc grad

Question 24

How does have water filled tracheoles aid gas exchange in insects.

Answer 24

Anaerobic respiration produces lactase which lowers the water potential of the muscle.
Water therefore moves in by osmosis.
This decreases pressure in the tracheoles drawing air in.

Question 25

Describe inspiration

Answer 25

• the diaphragm contracts/ flattens
• the external intercostal muscles contract
• increasing the volume of the thorax
• decreasing the pressure
• therefore air is forced in

Question 26

How are the lungs adapted for efficient gas exchange? (Concentration gradient)

Answer 26

Ventilation - air with low concentration of O2 / CO2 is replaced with air with high concentrations.

Circulation - blood with high O2 conc is replaced with blood with low O2 conc

Question 27

What is the effect of exercise on tidal volume, breathing rate, pulmonary ventilation and oxygen consumption?

Answer 27

TV - increases, because deeper breaths are taken during exercise.
BR - increases
PV - increases because you are taking more breaths and they are deeper.
O2 consumption - increases because more respiration is taking place.

Question 28

Membrane bound peptidases

Answer 28

Attached to membranes (eg the ileum) and hydrolyse DIPEPTIDES into amino acids

Question 29

How is starch digested?

Answer 29

Amylase - starch (polysaccharide)

Maltase - Maltose (disaccharide)

                Glucose x 2 ( monosaccharide)

Question 30

How are the lungs adapted for efficient gas exchange? (surface area)

Answer 30

• there are a lot of alveoli
• they have a folded membrane
• lots of capillaries
  = FAST DIFFUSION

Question 31

What is oxygen consumption?

Answer 31

Volume of oxygen used up per minute (in respiration)

Question 32

How are amino acids/ glucose absorbed?

Answer 32

• co transported with Na+
• Na + is pumped out to maintain conc grad
• AA or glucose move in against conc grad

Question 33

Define pulmonary ventilation

Answer 33

Total volume of air breathed in one minute.

Question 34

What is fibrosis?

Answer 34

• build up of scar tissue
• this increases the diffusion distance, decreasing the rate of diffusion
• scar tissue is less elastic, so alveoli don’t recoil, decreasing conc grad.

Question 35

How is tuberculosis transmitted and what are it’s affects?

Answer 35

• it is transmitted by droplet infection
• Bacteria are engulfed by a phagocyte
• destroys alveoli ( can cause fibrosis)

Question 36

What are the limitations of the tracheal system

Answer 36

• limits growth as relies on a short diffusion distance

Question 37

what is ventilation?

Answer 37

the supply of air to the lungs

Question 38

how are amino acids/glucose absorbed?

Answer 38

taken up at the ileum by fac diff

co transporter of Na+

this maintains the diffusion gradient for Na+

amino acids pass through the base of epithelial cells by fac diff

Question 39

how do you calculate pulmonary ventilation?

Answer 39

PV = Tidal volume x ventilation rate

Question 40

how do insects limit water loss?

Answer 40

ability to close spiracles

impermeable waxy cuticle

Question 41

what is tidal volume?

Answer 41

the volume of air breathed in/out in one normal breath

Question 42

what must large animals have to ensure effective gas exchange?

Answer 42

high SA:V

good blood supply

Question 43

what is breathing

Answer 43

the process of taking in and expelling air from the lungs

Question 44

name 1 difference between breathing and respiration

Answer 44

breathing = physical
respiration = biochemical

Question 45

How do plant cells close stomata

Answer 45

when plant cells have a lot of water the cells are turgid, keeping the cell open
when there is less water the cell becomes flaccid and the stomata close - conserving water

Question 46

how do xerophytic plants decrease the diffusion gradient for water between the inside and the outside of a leaf?

Answer 46

curled leaves, hairs trap water, sunken stomata - prevent water leaving

Question 47

How is a xerophyte adapted to reduce evaporation?

Answer 47

thick waxy cuticle / fewer stomata