3a - exchange systems

Question 1

what does every organism need to do

Answer 1

exhcnage things with its environment

Question 2

what do cells need to do

Answer 2

take in oxygen for aerobic respiration and nutrients

Question 3

what waste products do organisms have excrete

Answer 3

carbon dioxide and urea

Question 4

why does heat need to be exchanged

Answer 4

because organisms have to stay at roughly the same temperature

Question 5

what does the ability to exchange substances depend on

Answer 5

the organisms surface area to volume ratio

Question 6

smaller animals SA:V

Answer 6

have a relatively high surface area to volume ratio

Question 7

what do multicellular organisms need

Answer 7

exchange organs and mass transport systems

Question 8

what does every one of an organisms cell need to be supplied with

Answer 8

glucose and oxygen for respiration. and be able to remove waste proucts to avoid damaging itself

Question 9

what happens with single-celled organisms

Answer 9

these substances can diffuse directly into and out of the cell across the cell-surface membrane

Question 10

rate of diffusion in single celled organisms

Answer 10

quick because of the small distances the substances have to travel

Question 11

multicellular animals diffiusion

Answer 11

rate across the outer membrane is too slow becuase
- some cells are deep within the body, big distance between them and the outside environment
- larger animals have a low SA:V ratio, making it difficult to exchange enough substances to suplly a large volume of animal through a relatively small outer surface

Question 12

why do multicellular animals need exchange organs

Answer 12

to absorb and excrete substances
- to carry substances to and from their individual cells

Question 13

what is mass transport

Answer 13

in mammals, the circulatory system which uses blood to carry glucose and oxygen around the body. it also carries hormones, antibodies and waste like CO2.
in plants involves the transport of water ad solutes in the xylem and phloem

Question 14

what is the rate of heat loss dependent on

Answer 14

its surface area

Question 15

heat loss large volume

Answer 15

• surface area is relatively small, making it harder for it to lose heat from its body.

Question 16

heat loss small volume

Answer 16

surface area is relatively large so heat is lost more easily. this means smaller orgnaisms need a relatively high metabolic rate, in order to generate enough heat to stay warm

Question 17

heat loss compact shape

Answer 17

have a small suface area relative to their volume

Question 18

heat loss less compact shape

Answer 18

have a larger surface area relative to their volume increasing heat loss from their surface

Question 18

what effects whether an animal is compact or not

Answer 18

the temperature of its environment

Question 19

what do most gas exchange surfaces have in common

Answer 19

• large surface area
• theyre thin providing a short diffusion pathway across the gas exchange surface
• maintains a steep concentration gradient of gases across the exhcnage surface

Question 20

how do single celled organisms exchange gases

Answer 20

across their body surface
- absorb and release gases by diffusion through their outer surface
- have a relatively large surface area, a thin surface ad a short diffusion pathway so theres no need for a gas exchange system

Question 21

how do fish exchange gas

Answer 21

use a counter current system

Question 22

why do fish have special adaptations to get oxygen

Answer 22

becuase there is a lower concentration of oxygen in water than in air

Question 23

where does gas exchange occur in a fish

Answer 23

1. water enters the fishs mouth and passes out through the gill

Question 24

what is each gill made from

Answer 24

lots of thin plated called gill filaments which give a big surface area for exchange of gases

Question 25

what are gill filaments covered in

Answer 25

lots of tiny structures called lamellae which increase the surface area even more

Question 26

what do lamellae have lots of

Answer 26

blood capillaries and a thin surface layer of cells to speed up diffusion

Question 27

counter current system

Answer 27

blood flows through the lamellae in one direction and water flows over in the opposite direction.

Question 28

why is a counter current system useful

Answer 28

maintaines a large concentration gradient between the water and the blood. the concentration of oxygen in the water is always higher than that in the blood, so as much oxygen as posibble diffuses from the water into the blood

Question 29

how to insects exchange gases

Answer 29

using tacheae

Question 30

tracheae

Answer 30

miscroscopic air filled pipes used for gas exchange

Question 31

spiracles

Answer 31

pores on the surface

Question 32

insects exchanging gases process

Answer 32

-1. air moves into tracheae through spiracles 2. oxygen travels down the conc. gradient towards the cells 3. trachea branch off into smaller tracheoles and go to individual cells meaning oxygen diffuses directly into respiring cells 4. co2 from cells moves down its own concentration gradient towards the spiracles to be released into the atmosphere 5. insects use rhythmic abdominal movements to move air in and out of the spiracles

Question 33

tracheoles

Answer 33

has thin permeable walls and go to individual cells

Question 34

how do dicotyledonous plants exchange gases

Answer 34

at the surface of mesophyll cells

Question 35

what do plants need for photosynthesis and what does it produce

Answer 35

Carbon dioxide which produces oxygen as a waste gas, they need oxygen for respiration which produces carbon dioxide as a waste gas

Question 36

what is the main gas exchange surface for plants

Answer 36

the surface of the mesophyll cells in the leaf as they have a large surface area

Question 37

where are mesophyll cells found

Answer 37

inside the leaf, gases move in and out through stomata

Question 38

stomata

Answer 38

special pores in the epidermis

Question 39

how does the stomata work

Answer 39

can open to allow exchange of gases and close if the plant is losing too much water. guard cells control the opening and closing of stomata

Question 40

how have insects adapted to minimise water loss

Answer 40

if they are losing to much water they close their spiracles using muscles. they also have waterproof waxy cuticle all over their body and tiny hairs around their spiracles, both of which reduce evaporation

Question 41

how have plants adapted to minimise water loss

Answer 41

stoma kept open during day to allow gaseous exchange, water enter guard cells making them turgid which opens the stomatal pore. if the plant starts to get dehydrated, the guard cells lose water and become flaccid which closes the pore

Question 42

what is a xerophytes

Answer 42

plants specifically adapted for life in warm, dry or windy habitats where water loss is a problem

Question 43

what are lungs specialised for

Answer 43

gas exchange

Question 44

what do humans need to exchange

Answer 44

oxygen into the blood for respiration, get rid of carbon dioxide.

Question 45

what happens as you breathe in

Answer 45

air enters the trachea

Question 46

what does the trachea split into

Answer 46

two bronchi - one bronchus leading to each lung

Question 47

what does eah bronchus branch of into

Answer 47

smaller tubes called bronchioles

Question 48

what do the bronchioles end in

Answer 48

small air sacs called alveoli

Question 49

which parts work together to move air in and out

Answer 49

the ribcage, intercostal muscles and diaphragm

Question 50

what in ventilation

Answer 50

inspiration (breathing in) and expiration (breathing out)

Question 51

what is ventilation controlled by

Answer 51

the movememnts of the diaphragm, internal and external intercostal muscles and ribcage