Biology Chapter 6

Question 1

For efficient gas exchange, should surface area be comparatively small or large compared to its volume?

Answer 1

Large

Question 2

Small organisms generally have relatively ____ surfaces compared with their volumes

Answer 2

Large

Question 3

Large organisms have relatively ____ surfaces compared with their volumes

Answer 3

Smaller

Question 4

Why is diffusion alone insufficient for the needs of many organisms?

Answer 4

Oxygen would take too long to diffuse through the organism

Question 5

what are 2 ways organisms have overcome slow diffusion?

Answer 5

1. Flattened, no cell far away from the surface

2. Specialised gas exchange organs

Question 6

5 features of adapted exchange surfaces:

Answer 6

1. Large surface area to volume ratio
2. Very thin
3. Partially permeable
4. Movement of environmental medium
5. Movement of internal medium

Question 7

Why are specialised exchange surfaces located on the inside of the body?

Answer 7

They are thin and can be easily damaged

Question 8

Gas exchange in single-celled organisms occurs by:

Answer 8

Diffusion

Question 9

2 ways in which insects can reduce water loss:

Answer 9

1. Waterproof covering

2. Small surface area to volume ratio

Question 10

What are tracheoles:

Answer 10

Small branches of the trachea

Question 11

What increases ventilation in insects?

Answer 11

Muscle movements

Question 12

What are spiracles?

Answer 12

Tiny pores on the surface of the body

Question 13

Describe 2 ways in which gases can move in and out of the tracheal system:

Answer 13

1. Along a diffusion gradient, as oxygen is used up in respiration and carbon dioxide is produced. Therefore, oxygen moves in and carbon dioxide moves out
2. Ventilation, aided by the movement of insect’s muscles

Question 14

Why must insects be small in order for this system of gas exchange to function properly?

Answer 14

Short diffusion pathway

Question 15

What is the name of the specialised gas exchange system in fish?

Answer 15

The gills

Question 16

Where are the gills located?

Answer 16

Behind the head

Question 17

What is the function of the gill lamellae?

Answer 17

To increase the gill surface area

Question 18

What is the countercurrent flow?

Answer 18

Water if forced over the gill lamellae in the opposite direction to the way the blood flows through the lamellae

Question 19

Why is the countercurrent flow important?

Answer 19

To ensure maximum possible gas exchange

Question 20

Gas exchange in plants is similar to:

Answer 20

insects

Question 21

2 features of the plant gas exchange system:

Answer 21

1. All cells close to external air

2. More rapid diffusion in the gas phase

Question 22

Adaptations for rapid diffusion in plants:

Answer 22

1. Flat, thin shape
2. Stomata
3. Air space network in the mesophyll

Question 23

What are stomata?

Answer 23

Tiny pores, mainly distributed on the underside of the leaves

Question 24

What is the function of the guard cells?

Answer 24

To open and close the stomata

Question 25

Why is closing stomata important?

Answer 25

To prevent them from loosing too much water

Question 26

Suggest how the air spaces aid photosynthesis

Answer 26

Having spaces allows the carbon dioxide that enters through the stomata on the underside of the leaf to reach the palisade cell which are located nearest the sunlight. This allows an adequate supply of carbon dioxide for photosynthesis

Question 27

What are xerophytes?

Answer 27

Plants living in dry conditions that have developed adaptations to limit water loss

Question 28

Give 5 adaptations of xerophytes to reduce water loss

Answer 28

1. Thick, waxy cuticle to form a waterproof barrier 2. Rolling of leaves to reduce water potential gradient, so reduced evaporation and so transpiration 3. Hairy leaves to reduce water potential gradient, so reduce evaporation and so transpiration 4. Stomata in pits or grooves, so reduced evaporation and so transpiration 5. Reduced surface area to volume ratio, so reduced evaporation that can tale place from the leaf, so reduces transpiration

Question 29

What is the structure of the trachea?

Answer 29

Flexible tube supported by cartilage. Walls are made of muscle, and epithelium is ciliated with goblet cells that provide mucus

Question 30

What is the function of trachea?

Answer 30

Provides a non-collapsible airway. Mucus traps dirt and microorganisms and is delivered to the throat

Question 31

What is the structure of the bronchi?

Answer 31

Two divisions of trachea. Similar in structure to trachea, supported by cartilage which reduces as the bronchi decrease in size

Question 32

What is the structure of the bronchioles?

Answer 32

Made of smooth muscle lined with epithelial cells - can constrict

Question 33

What is the function of bronchioles?

Answer 33

Control the air flow into and out of the alveoli

Question 34

What is the structure of the alveoli?

Answer 34

Stretchy air sacs of collagen and elastic fibres

Question 35

What is the function of the alveoli?

Answer 35

Main gas exchange surface

Question 36

An asthma attack involves constructing of the air passages. Which of the parts above would you expect to constrict the most and why?

Answer 36

Bronchioles, as they are made of muscle with little cartilage to support them

Question 37

What occurs when air pressure in the lungs is greater than air pressure outside?

Answer 37

Expiration

Question 38

Which 2 sets of muscles are involved in the mechanism of breathing?

Answer 38

1. Diaphragm muscles | 2. Intercostal muscles

Question 39

Relaxation of the internal intercostal muscles leads to:

Answer 39

Expiration

Question 40

Contraction of the external intercostal muscles leads to:

Answer 40

Inspiration

Question 41

Is inspiration active or passive?

Answer 41

Active

Question 42

What happens to the internal intercostal muscles while the external ones are contracting?

Answer 42

They relax

Question 43

Which 2 events increase the volume in the lungs?

Answer 43

1. ribs move upwards and outwards | 2. Diaphragm flattens

Question 44

How does increased lung volume affect pressure?

Answer 44

Decreases it

Question 45

Is expiration active or passive?

Answer 45

Largely passive

Question 46

What is the resting position of the diaphragm?

Answer 46

Dome-shaped

Question 47

What is the main cause of expiration during normal quiet breathing?

Answer 47

The elastic recoil from the tissue of the lungs

Question 48

which 2 factors can we measure to calculate pulmonary ventilation?

Answer 48

1. Tidal volume | 2. Ventilation rate

Question 49

How does oxygen move through the gas exchange system?

Answer 49

Trachea to the bronchi to the bronchioles to the alveoli down the pressure gradient to the alveolar epithelium to the capillary endothelium to the blood down the diffusion gradient