unit 3

Question 1

Why do smaller organisms require more metabolic energy

Answer 1

Smaller organisms looser more heat to their surroundings
therefore require more metabolic energy
Consume more than larger organisms and require more oxygen per unit of body weight

Question 2

Why do multi cellular organisms require specialised gas exchange systems

Answer 2

Larger organisms have a smaller sA:V ratio
Because of this diffusion through the surface of the organism cannot work
They require specialised gas exchange systems to carry out efficient gas exchange of oxygen and carbon

Question 3

Features of good gas exchange

Answer 3

Have a high SA to volume ratio
Thin
Maintaining steep conc gradient
Permeable to gases selectively
Moist
Transport medium

Question 4

Fishes gas exchange system

Answer 4

Gills

Question 5

What do hills contain

Answer 5

Serval hill Arches with many lamellae along the Filament this provides a large surface area which allows efficient gas exchange system

Question 6

How are Llamellae adapted

Answer 6

Thin
Counter current system
Efficient blood supply
Many llamellae

Question 7

What is a counter current system

Answer 7

I’m involved two fluids moving in opposite directions there is always more oxygen in the water than there is in the blood this allows a constant diffusion gradient. It maximises gas e g singe between two fluids

Question 8

How do insects respire: spircles

Answer 8

Air moves in from pores on the isnectrs surface called spiracles

Question 9

What is the main gas exchange surface in a plant

Answer 9

Mesophyll cells

Question 10

How are mesophyll cells adapted

Answer 10

Large surface area

Question 11

How are insects adapted to efficient Gas exchange

Answer 11

Concentration gradient
Osmosis at the end of tracheoles
Abdominal pumping
Tracheols have thin permeable wall that goes to individual cells

Question 12

How do insects control water loss

Answer 12

Close spiracles using muscles
They have a waterproof waxy cuticle all over their body
Tiny hairs around spit ales which reduce evaporation

Question 13

How do plants reduce water loss

Answer 13

Water enters guard cells making them turgid which opens the stomat pore

Question 14

Xerophytes

Answer 14

Stomata sink in pits to trap water capote reducing the concentration gradient of water between the leaf and hair
Layers of hairs on the epidermis to trap water vapour
Curled leaves with the stomata inside protecting them from wind
Reduced number of stomata
Thicker waxy waterproof cuticles

Question 15

What is the heart made out of

Answer 15

Cardiac muscle

Question 16

2 key feautures of cardiac muscle

Answer 16

Myogenic- contracts and relaxes without nervous or hormone stimulation
Doesn’t fatigue- as long as it has a supply of oxygen

Question 17

What do the conorary arteries do

Answer 17

Surround the heart and supply heart with oxygenated blood
It branches off aorta

Question 18

What are the 4 chambers in the heart

Answer 18

Right left atrium
Right left ventricle

Question 19

Key features of the atrium 3

Answer 19

Thinner muscular walls
Elastic to stretch as blood moves on
Moves to ventricles

Question 20

Right ventricle

Answer 20

Thinner muscular wall because it supplies the lungs which needs lower pressure to allow time for gas exchange

Question 21

Left ventricle

Answer 21

Higher pressure as it supplies around the body
Larger contraction high pressure

Question 22

2 veins

Answer 22

Vena cava and pulmonary vein

Question 23

What does the vena cava do

Answer 23

Carried deoxygenated blood from body to right atrium

Question 24

Pulmonary vein

Answer 24

Carries oxygenated blood from lungs into left atrium

Question 25

What are the two arteries

Answer 25

PA carries deoxygenated blood from RV INTO lungs
Aorta oxygenated blood from LV to test of the body

Question 26

Valves

Answer 26

Semi lunar valve
Atrioventricular valve
Bicuspid
Tricuspid

Question 27

What do valves do

Answer 27

Alow blood to flow in one direction
Prevents back flow
Door analogy

Question 28

What breaks down carbohydrates

Answer 28

Amalayse and Maltase and memebrane bound disaccharidase

Question 29

Inspiration

Answer 29

-EICM contracts and the ribs move down and out
-IICM relax
-diaphragm contacts and flattens
-volume increases
-pressure decreases
-air moves in from atmospheric pressure into lower pressure

Question 30

Expiration

Answer 30

-EICM relax
-IICM contact and ribs move up and inwards
-diaphragm relaxes
-volume decreases
-pressure increases
-air moves from higher pressure to atmospheric pressure

Question 31

mass flow in plants

Answer 31

1) sucrose is produced in the in the source cell and by facillitated diffusion diffuses into the cell wall space of the companion cell
2. hydrogen ions are transported into the cell wall space from the cell wall space between the companion cell and sieve tube elemnet
3. by co transport the hydrogen ions move down its concentration graidient and sucrose against it
3. this lowers the water potential in the sieve tube element. water from the xylem by osmosis dissues into the sieve tube element this creates hydrostatic pressure in the sieve tube elemt
sucrose by active transport diffuses into the sink celkl
this lowers the water potential in the sink cell
water in the sieve tube elemnt diffuses into the sink cell by osmosis
this decreases the hydrostatic pressurfe in the sieze tube element this hydrostatic pressure graidient is what drives mass flow