The principles of exchange and transport

Question 1

what are the essential substances that cells must obtain for respiration?

Answer 1

-oxygen and glucose

Question 1

what are examples of things cells must remove during respiration?

Answer 1

-urea and carbon dioxide

Question 2

where does respiration occur in unicellular and multicellular organisms?

Answer 2

-through the cell surface membrane in unicellular
-in multicellular through a specialized transport system

Question 3

the rate of exchange of substances depends on…

Answer 3

-the organisms surface area that is in contact with the surrounding environment

Question 4

the surface area is…

Answer 4

• the total number of cells in direct contact with the surrounding environment

Question 5

the volume is….

Answer 5

• the total three dimensional shape occupied by the metabolically active tissues

Question 6

what is the surface area to volume ratio in small animals and larger animals and why

Answer 6

-large is small animals and small in larger animals because less cells are in contact with the surrounding environment

Question 7

What does surface area influence?

Answer 7

• the rate of supply of metabolites

Question 8

the volume of metabolically active tissues influences what?

Answer 8

• the demand for metabolites

Question 9

How do u find the surface area and volume?

Answer 9

-SA= face of one side multiplied by the amount of sides
-V= length by breadth by height

Question 10

How do small animals gain their requirements through their large sa:v ratio ?

Answer 10

-through their body surface

Question 11

why can large animals not gain requirements through their body surface?

Answer 11

-not enough of their cells are in contact with the surrounding environment and so they have specialized exchange surfaces to facilitate transport of substances.

Question 12

what is an example of a small animal with a large sa:v ratio?

Answer 12

-a flat worm flattens their body to increase surface area

Question 13

why does a large surface area aid passive and active transport? and what is an example of an organism that can achieve this?

Answer 13

-in some organisms they can achieve this by flattening their surface e.g. flatworms
-this decreases the overall distance for diffusion

Question 14

why must exchange surfaces be thin and permeable for passive and active transport? What is an example of this in mammals?

Answer 14

-they are thin so that the rate of diffusion is maximized and the distance is short e.g. in the alveoli gases only diffuse through two layers the alveoli and the capillary

Question 15

how is a large concentration gradient maintained in mammals?

Answer 15

-through a transport system and a ventilating mechanism

Question 16

How are low levels of oxygen created in cells and how does this create a concentration gradient?

Answer 16

-the use of oxygen in the tissues creates low levels of oxygen in the cells therefore a concentration gradient exist that enables oxygen to diffuse from the atmosphere

Question 17

what do larger organisms have in order to maintain a diffusion gradient and why do they have this? What else is required to maintain a concentration gradient?

Answer 17

-they have specialized exchange surfaces, unaided diffusion usually isn’t enough to remove or deliver respiratory gases
-in these organisms a ventilating system is required to maintain a concentration gradient e.g. breathing in mammals

Question 18

What is exchanged and transported across the membrane of a root hair cell?

Answer 18

-root hair cells do not contain chloroplasts and so do not photosynthesize but the do respire
-meaning they take in oxygen and give out carbon dioxide
-O2 is needed for respiration in the mitochondria to produce ATP energy, O2 is found in the air spaces in the soil

Question 19

how is a high rate of respiration obtained in the root hair cells?

Answer 19

-in aerated soil there is a high rate of respiration
-in water logged soils there is less oxygen available and so there is a reduced rate of active uptake.

Question 20

how is a concentration gradient maintained in a root hair cell? Where does the water go?

Answer 20

-water moves from soil water where there is a high concentration to the vacuole and cytoplasm where there is a low concentration

Question 21

what are the names of the mineral ions that are transported across the cell membrane?

Answer 21

potassium, magnesium, calcium, nitrogen, phosphite and sulfate

Question 22

what are the three things a membrane must be in order to let mineral ions through?

Answer 22

-must be permeable, thin and moist

Question 23

what are the names of the two types of vessels in the vascular bundle and what do they transport?

Answer 23

• the xylem transports water and minerals
  the phloem also transports minerals

Question 24

what is the main feature of the root hair cells ?

Answer 24

-their extensions which increases their surface area for absorption and exchange

Question 25

describe the structure of the leaf and what each layer does briefly

Answer 25

-flattened which ensures short diffusion distance
-tightly packed upper palisade mesophyll layer which traps light
- loose packed lower spongy mesophyll layer provides air space which creates huge surface area for gas exchange

Question 26

what is the blood capillaries made of and why

Answer 26

• made of squamous endothelium which makes it thin, permeable, moist and provides a short distance for gas exchange

Question 27

what are 6 adaptations that blood capillaries have for gas exchange

Answer 27

-one cell thick and made up of squamous endothelium and is permeable to H2O, CO2 and O2
-large surface area for diffusion
-close to body cells
-blood flows slowly giving time for diffusion
-high metabolic/ respiration rate
-always found in a network

Question 28

how do blood capillaries maintain a concentration gradient ?

Answer 28

-blood entering the capillaries is under high pressure which forces water, glucose, amino acids and oxygen out through the capillary walls
- it is the transport of oxygenated blood to the capillaries and deoxygenated blood away from the capillaries that maintain the concentration gradient

Question 29

what is the function of the red blood cells?

Answer 29

• transport respiratory gases
• hemoglobin helps to do this

Question 30

what are 6 adaptations of red blood cells

Answer 30

-large surface area to volume ratio
-large amounts of hemoglobin and because the cell is small all hemoglobin is close to the cell membranes
- no nucleus
-no mitochondria, gases are exchanged by diffusion which is a passive process and doesn’t need energy
-cell membrane is permeable to CO2 and O2
because of its shape it has more resistance to osmotic effect

Question 31

what are 5 characteristics of the alveoli ?

Answer 31

-large surface area
-thin respiratory membrane both capillary and alveoli are made of squamous endothelium creating a short diffusion pathway
-moist outer surface
-surfactant in outer layer which stops alveoli from collapsing
-rich blood supply and ventilation system helps maintain diffusion gradient ( high O2 in alveoli and high CO2 in blood)