Chapter 7

Question 1

Why can singled celled organism rely on diffusion to take in the oxygen needed and release the carbon dioxide

Answer 1

1) metabolic activity is low so oxygen demand and carbon dioxide production is low
2) the surface area to volume ratio is large
3) there is a small distance substances must travel

Question 2

Why must multicellular organisms have specialised exchange surfaces?

Answer 2

1) they have billions of cells so metabolic activity is incredibly high thus so is oxygen demand and carbon dioxide production
2) the distance to inner cells is too far to diffuse
3) the surface area to volume ratio is small

Question 3

How do you calculate surface area to volume ratio?

Answer 3

By dividing surface area by volume

Question 4

What are the features of an efficient exchange surface?

Answer 4

1) a large surface area providing the area needed for exchange
2) a good blood supply/ ventilation system to help maintain a high concentration gradient
3) thin layers- so the diffusion pathway is short speeding up the process

Question 5

Give an example of a cell/ organ with a good blood supply/ good ventilation system

Answer 5

The alveoli have a large capillary network with a good blood supply and are ventilated constantly as we breath

The gills have a capillary network with a good blood supply and are constantly ventilated as water passed over them

Question 6

Give an example of a cell with a large surface area

Answer 6

A root hair cell had a long ‘hair’ like projection which gives it a larger surface area for absorption

Question 7

Give an example of a organ with thin layers

Answer 7

The alveoli are made from a single layer of flat cells called alveolar which decrease the distance O2 and CO3 have to travel

Question 8

What is cartilage?

Answer 8

Cartilage is in the walls of the trachea and bronchi, they are flexible and provide support to prevent collapse when pressure decreases during inhalation

Question 9

What is the cilliated epithelium?

Answer 9

Beats mucus away from the alveoli to the throat where it is swallowed

Question 10

What are goblet cells?

Answer 10

Goblet cells secrete mucus which traps microorganisms and dust stopping them reaching the alveoli

Question 11

What is smooth muscle?

Answer 11

In the walls of the trachea , bronchi and bronchioles and allows diameter to be controlled by tensing and relaxing

Question 12

What are elastic fibres?

Answer 12

In the walls of the trachea , bronchi and bronchioles they help exhalation by stretching as the lungs inflate and recoil to help push the air out while exhaling

Question 13

Which components does the trachea and bronchi have?

Answer 13

The trachea had cartilage , cilliated epithelium, goblet cells , smooth muscle and elastic fibres

Question 14

Which components do the bronchioles have?

Answer 14

Cilliated epithelium, smooth muscle and elastic fibres

Question 15

Which components do the alveoli have?

Answer 15

Elastic fibres

Question 16

Explain the process of inspiration and what type of process it is

Answer 16

1) the external intercostal muscles and the diaphragm contract causing the ribcage to move up and out and the diaphragm to flatten increasing the volume
2) lung pressure thus decreases causing air to flow into the lungs
This is an active process

Question 17

Explain the process of expiration and what type of process it is

Answer 17

1) the external intercostal muscles and diaphragm relax causing the ribcage to move down and in and diaphragm curve decreasing the volume
2) lung pressure increases forcing air out
It is a passive process

Question 18

What is forced expiration?

Answer 18

Forced expiration is when the internal intercostal muscles are contracted forcing air out

Question 19

What is vital capacity?

Answer 19

Vital capacity is the maximum volume of air that can be breathed in or out

Question 20

What is oxygen consumption

Answer 20

Oxygen consumption is the rate at which an organism uses up oxygen

Question 21

Ventilation rate=

Answer 21

Ventilation rate= tidal volume X breathing rate

Question 22

What is breathing rate?

Answer 22

Breathing rate is the number of breaths per minute

Question 23

What is tidal volume?

Answer 23

Tidal volume is the volume of air in each resting breath

Question 24

What is a spirometer

Answer 24

A spirometer has an oxygen filled chamber with a movable lid
The subject breathes through a tube causing the lid to move up and down
A pen is attached to the lid and writes on a rotating drum creating a spirometer trace
The soda lime in the tube absorbs the carbon dioxide

Question 25

How does gas exchange occur in bony fish?

Answer 25

The fish opens its mouth lowering the floor of the buccal cavity decreasing the pressure so water is sucked in. The fish then closes its mouth raising the floor increasing the pressure. This forces is water out of the cavity and over the gills forcing your operculumto open and water to flow out of the girls.

Question 26

How are the gills adapted to thier function?

Answer 26

The girls have a countercurrent system in a high oxygen concentration is maintained throughout the gill.
The gills filaments are stacked which give it a high surface area for diffusion when hold apart by water
They have lots of capillaries and thin and surface layers of cells for a short diffusion pathway

Question 27

How does gas exchange occur in insects

Answer 27

Air enters the insect through the spiracles into the tracheae aided by ventilation through the insects abdominal movement to change body volume.
The trachea branches into tracheoles at the end of which are filled with tracheal fluid
the oxygen diffuses into the tracheal fluid and then into the cells of the organs and CO2 out making its way back to the spiracles

Question 28

How do you dissect a fish

Answer 28

Put on a lab coat and gloves
Place your chosen fish in a dissection tray
Push back the operculum use scissors to Remove the gills by cutting through the bone at The top and bottom of each Gill arch
Observe the gills filaments and sketch

Question 29

How do you dissect an insect?

Answer 29

Fix the insect to a dissection board
Observe the spiracles using a magnifying glass Remove piece of the exoskeleton from the abdominal
Filk the abdomen with saline solution using a syringe
Observe the trachael network of thin silvery tubes or placed under a microscope