Gaseous Exchange

Question 1

role of respiratory system

Answer 1

enables gaseous exchange to occur

Question 2

role of excretory system

Answer 2

responsible for removing metabolic wastes from the blood and to expel them from the organism

e.g. carbon dioxide (expelled through lungs) and nitrogen (through urine)

Question 3

role of circulatory system

Answer 3

transports gases (oxygen, carbon dioxide, nutrients, waste products, hormones, antibodies)

responsible for maintaining a constant internal environment e.g. ph levels

also removes any toxins or pathogens

responsible for duration of heat

Question 4

how are gas exchange surfaces adapted to be efficient

Answer 4

thing

large SA

near blood supply

moist

Question 5

how do fishes increase the surface area:volume ration

Answer 5

have filaments and lamellae in fills. these are very long and thin, maximising the SA

Question 6

how do mammals increase the surface area:volume ration

Answer 6

the tissue of the gas exchange surfaces folds back on itself.

these folds of the alveoli increase the SA

Question 7

do insects require a large SA:volume ratio

Answer 7

no

oxygen diffuses straight from the tracheoles into the cells, so the tracheoles reach every cell, but there is no need to have a large surface area:volume ratio at each place where gas exchange occurs

Question 8

how do fishes keep their gas exchange surface moist

Answer 8

they live in water, and get oxygen from the water, so keeps their gills moist

Question 9

how do mammals keep their gas exchange surface moist

Answer 9

Mammals have mucus in the trachea keeping it moist, and the whole gas exchange system is internal to keep this moisture in.

Question 10

how do insects keep their gas exchange surface moist

Answer 10

Insects have water at the ends of their tracheoles for oxgen to dissolve in to diffuse. The gas exchange system is internal to reduce water loss, and the spiracles can open and close to control it, depending on environmental conditions.

Question 11

do insects, mammals and fishes have a gas exchange system

Answer 11

mammals and fish do

insects don’t

Question 12

does a bigger insect find it harder or easier for oxygen to get to every cell of diffusion

Answer 12

harder

Insects don’t have a circulatory system. Their tracheoles reach every cell, and they rely on diffusion for oxygen to reach each cell.

Question 13

are mammals, fishes and insects limited in size?

Answer 13

mammals and fishes are not, because the oxygen is transported by the blood, meaning their sizes are unlimited

insects are limited in size. The bigger the insect, the harder it is for oxygen to get to every cell by diffusion.

Question 14

how do mammals, fish and insects get their air

Answer 14

mammals and insects get it from the air

fish from the water

Question 15

why is water hard to ventilate

Answer 15

because it is more vicious than air

Question 16

why do fish have a more efficient gas exchange system

Answer 16

because water is hard to ventilate as it is more vicious than air, so it’s harder to get the oxygen from the water

Question 17

describe the direction of flow for a fish

Answer 17

unidirectional

the unidirectional flow is achieved by taking water in through their mouths, then pushing it through the gills and out the operculum.

The water flows through the lamellae in the gills in the opposite direction to the blood. (called the counter-current system and allows for the most efficient diffusion of gases between the water and the blood)

The concentration gradient is maintained the whole way through the gills, because the most oxygenated water meets the most oxygenated blood, and the least oxygenated water meets the least oxygenated blood.

Question 18

If water and blood flowed in the same direction in a fish, what would happen?

Answer 18

If the water and blood flowed in the same direction, the oxygen concentration of blood and water would equalise at 50% half way through the gills, so not as much oxygen would be absorbed by the blood.

Question 19

Describe tidal ventilation in insects and mammals

Answer 19

means the air goes in and out the same way.

This means with each breath, not all of the old air makes it out of the body, so not all of the air coming in is new.

Because of this, mammals and insects don’t get the maximum amount of oxygen out of the air.

Question 20

Transport systems in unicellular organisms

Answer 20

all nutrients needed can be diffused from the external environment over their surface area

Wastes can just be removed from cells by diffusion as well

e.g. can transport oxygen and urea out of bodies by diffusion or osmosis easily

Question 21

how can wastes in unicellular organisms be removed

Answer 21

Wastes can just be removed from cells by diffusion

Question 22

in multicellular organisms, do they have a surface area great enough to provide nutrients for all the organisms cells?

Answer 22

no

most of cells inside organisms are too far from the surface of their bodies and diffusion and osmosis are too slow to be relied on

Question 23

what do the transport systems in multicellular organisms do

Answer 23

carry nutrients to bodies cells

transports food and oxygen

carry wastes away

Question 24

where does osmosis and diffusion occur in multicellular organisms

Answer 24

diffusion and osmosis would take place between he transport system and the cells

Question 25

what is an open circulatory system

Answer 25

the more basic type of circulatory system

referred to as open because blood is not contained within an enclosed circuit of vessels.

blood flows from the heart through open-ended vessels and, when it reaches the end of the vessels, it flows directly over the tissues

while the tissues are bathed in blood, gas exchange occurs. Blood then freely flows back into vessels that direct the blood back to the heart

Question 26

examples of organisms that use an open circulatory system

Answer 26

grasshoppers

clams

snails

Question 27

what is a closed circulatory system

Answer 27

a closed circulatory system is more structured and controlled

the blood of a closed system always flows inside vessels. These vessels make up the plumbing circuit of the body and can be found throughout the entire body

this plumbing circuit can be broken down into three different types of vessels that transport blood throughout the body: arteries, capillaries and veins.

arteries = responsible for moving blood AWAY from your heart and to your tissues

When blood gets to the tissues it is contained within capillaries

capillaries = very small vessels with thin walls. These thin walls make it possible for gas and waste exchange to occur between your blood and your tissues

the blood then leaves the capillaries and goes into the veins, which bring blood back to your heart

Question 28

describe stomates and where they are found

Answer 28

located on leaves of plants

they are pores in the leaf which enable the diffusion of gases

present on the upper and lower sides of leaves, but mainly on the lower side

Question 29

describe the role of stomates

Answer 29

stomates receive the gases needed for photosynthesis (not respiration)

stomates can open and close: when open, gas exchange occurs in the leaf and photosynthesis occurs, but when they close, the rate of photosynthesis slows

Question 30

how are the stomates controlled

Answer 30

the opening and closing of Stomates is controlled by guard cells

this is dependent on stimuli such as: light, low CO2 levels, an internal clock, water deficiency, and high temperatures

Question 31

describe lenticels

Answer 31

These are pores on the woody stems of plants.

The gases needed for respiration are diffused through lenticels

Carbon dioxide also diffuses out

Question 32

describe xylem and its role

Answer 32

Transport water and mineral ions up the plant stem to the leaves

Consists of dead cells, whose cross-walls (connection between cell walls) have been broken away, creating a continuous tube

Xylem also gives strength and rigidity to the plant

Question 33

describe phloem and its role

Answer 33

Transport the products of photosynthesis (sugars) throughout the whole plant

Made of long columns of ‘sieve tube cells’, which have holes in their cell walls, so that the cytoplasm is mixed and diffusion of sugars occurs

Organic material in the phloem is transported up and down the plant

Question 34

describe root hair and its role

Answer 34

These structures are on the surface of the roots

They provide a large surface area for water to diffuse into the plant

Water enters the plant via the root hairs and then enters the xylem

Question 35

describe transpiration

Answer 35

Transpiration is the loss of water from a plant through the stomates in leaves

When stomates are open, gases flow in for photosynthesis. However, at the same time, water is lost by evaporation. This water loss is transpiration

As water is lost, more water flows in through the roots

The constant flow of water from roots, to vascular tissue, to leaves and into the air is called the transpiration stream

Some plants have adaptations to reduce transpiration, such as sunken stomates, small leaves or hairy leaves.

Question 36

what are radio isotopes

Answer 36

are forms of elements which are radioactive can be used to trace biochemical pathways

Question 37

how can the pathway of radio isotopes be traced

Answer 37

As the radioactive elements take the same pathway as non-radioactive elements, the pathways can be traced using techniques such as photographic paper

Question 38

Thallium-201 is used when?

Answer 38

in diagnosing damaged heart muscle.

As it will only accumulate in healthy heart muscle, it will reveal areas that need the be treated