Exchange of materials

Question 0

What is active transport?

Answer 0

movement of particles from an area of low concentration to an area of high concentration, against a concentration gradient, using energy released from mitochondria in respiration

Question 1

What must cells be able to do?

Answer 1

transport substances in and out

Question 2

Give examples of active transport

Answer 2

Ions into root hair cells

glucose into kidney tubules

Question 3

What is osmosis?

Answer 3

movement of water molecules from a dilute solution to a more concentrated solution across a semi permeable membrane

Question 4

Why is osmosis across a semi permeable membrane?

Answer 4

on small molecules can fit through pores

Question 5

When do molecules stop moving to high concentrated solution?

Answer 5

when equilibrium is reached, resulting in no overall net movement

Question 6

What happens when animal cell is placed in dilute solution?

Answer 6

water molecules move into animal cell and membrane can’t stand those levels of high pressure so it bursts

Question 7

What happens when a plant cell is placed in a dilute solution?

Answer 7

cell swells and cytoplasm and membrane push against cell wall. Cell wall resists further expansion and become turgid.

Question 8

What happens when an animal cell is placed in concentrated solution?

Answer 8

Water moves out of animal cell, causing it to shrivel up

Question 9

What happens when a plant cell is placed in a concentrated solution?

Answer 9

membrane and cytoplasm shrink away from cell wall, causing it to become flaccid.

Question 10

What must the concentration of water outside cells be?

Answer 10

constant

Question 11

What happens during exercise?

Answer 11

Reduction of glucose which is needed for respiration to provide energy

Sweat - lose water and mineral ions (electrolytes) so cells work inefficiently

Question 12

What do sports drinks do?

Answer 12

Replace water
Replace electrolytes
Replace sugar

Question 13

What factors make exchange surfaces more effective?

Answer 13

Large surface area
thin (short diffusion path)
efficient blood supply - extensive capillary network in exchange organs
ventilated

Question 14

How are lungs adapted to exchange O2 and CO2?

Answer 14

Alveoli:
good blood supply 
large surface area
thin - O2 can diffuse in quicker and CO2 out
Ventilated - breathe in and out

Question 15

How are small intestines adapted to exchange substances?

Answer 15

Inside surface: Villi and microvilli which increase surface area

efficient blood supply - dense network of capillaries
thin
many mitochondria - provide energy for active transport

Question 16

What happens when we breathe in?

Answer 16

intercostal muscles contract
ribcage moves up and out
diaphragm contracts, pulling downwards
lung volume increases and air pressure inside decreases

Question 17

What happens when we breathe out?

Answer 17

Intercostal muscles relax
Ribcage moves down and in 
diaphragm relaxes, moving up
lung volume decreased and air pressure inside increases 
air pushed out of lungs

Question 18

What is a negative pressure aid to breathing and how does it work?

Answer 18

Iron lung:

Person aced in giant metal container, sealed tightly at neck so no air can leak
Air pumped out of iron chamber, lowering pressure
higher air pressure outside so air drawn into lungs
Reverse this so that air rushes back in and lungs deflate and push air back out again

Question 19

Give positive evaluation points of iron lung

Answer 19

keeps patient alive

breathes for patient

Question 20

give negative evaluation points of iron lung

Answer 20

Patient has to lie inside large machine

Doesn’t work as well as positive pressure breathing system

Question 21

What is a positive pressure system and how does it work?

Answer 21

Large inflatable bag controlled by doctor
controls amount of air that goes in through mask
con be controlled by machine which regulates breathing

Question 22

What are the advantages of positive pressure breathing systems?

Answer 22

Quick and easy to use

Machine based systems can be portable and used for long periods

Question 23

What are the disadvantages of positive pressure breathing systems?

Answer 23

They are only temporary

Question 24

How does CO2 get into leaf? What is it required for?

Answer 24

via diffusion.

Required for photosynthesis and is waste product of respiration

Question 25

How to O2 exit leaf?

Answer 25

Via diffusion
required for respiration
waste product of photosynthesis

Question 26

What enter via roots?

Answer 26

water and mineral ions

Question 27

What is the function of root hair cells?

Answer 27

increase surface area for water and mineral ions

Question 28

How are leaves adapted to exchange materials?

Answer 28

flat with internal air spaces
thin so short diffusion path
stomata which are controlled by guard cells and open and close to allow O2 and CO2 out and in
spongy Mesophyll which increases surface area

Question 29

what is lost through stomata and why?

Answer 29

water vapour because of evaporation in leaves

Question 30

When do stomata close and why?

Answer 30

if plants lose water faster than its replaced by roots then stomata close to prevent wilting

Question 31

When is evaporation more rapid?

Answer 31

hot, dry and windy conditions