Topic 2

Question 1

What is metabolism

Answer 1

sum of all chemical reactions in the body

Question 2

Job of Salivary glands and pancreas
Stomach 
Small intestine (and adaptation)
Liver 
Large intestine

Answer 2

produce enzymes to break down food

protease to break down food

Absorption of nutrients into blood
Adapted to have a large SA as it is covered in villi. Good blood supply and short diffusion to the blood vessels. This greatly increases diffusion and active transport from the small intestine to blood

produces bile
=> gall bladder
=> Neutralises acid
=> Emulsifies fat

absorbs water

Question 3

What are enzymes?

Answer 3

Biological catalysts

Made of protein

Question 4

Describe lock and Key method (3m)

Answer 4

The shape of substrate is complementary to shape of active site
=> form a enzyme-substrate complex
=> as they are specific to each other

Once bound, products released

Question 5

Factors that affect enzymes

Answer 5

Temperature:

Body is 37 degrees
Rate of reaction will increase as temp increases
=> if the temperature goes too high then it will rapidly decrease rate of reaction until it stops

=> Becomes denatured
=> substrate no longer fits in

pH:

Optimum for body is 7pH
If pH gets too high/ low => forces holding amino acids will break
=> changing shape of active site
=> denatured

Question 6

Job of:

Carbohydrase
Amylase
Protease
Lipases

Answer 6

Carbohydrases break down carbohydrates
=> to simple sugars.

Amylase is a carbohydrase which breaks down starch.

Proteases break down proteins
=> to amino acids.

Lipases break down lipids (fats)
=> to glycerol and fatty acids.

Question 7

Use of Bile and why it is useful

Answer 7

It is alkaline to neutralise HCL acid from stomach
Emulsifies fat to form droplets which increase SA

Alkaline conditions + Large SA
=> INCREASE RATE of fat broken down by lipase

Question 8

How does gaseous exchange occur (4m)

Answer 8

Air passes into lungs through the trachea
=> trachea contains rings of cartilage preventing trachea from collapsing during inhalation

Trachea splits into 2 smaller tubes called Bronchi
- Then sub divides into smaller tubes called bronchioles

At the end of bronchioles there are air sacs called alveoli

Alveoli- where gases diffuse in and out of the bloodstream (site of gas exchange)

Question 9

Adaptation of this process

Answer 9

Millions of Alveoli + spherical shape- large surface area
Thin walls so diffusion path is very short
Very good blood capillary supply

Once oxygen is diffused it is removed rapidly- ensures steep conc. gradient
We increase the rate of diffusion
Bring fresh oxygen and take away Co2
This makes conc. gradient high for gases
=> increases rate of diffusion

Question 10

How does blood pump around the body (4m)

Answer 10

Left ventricle pumps blood around the entire body (more muscular)
Right ventricle only pumps blood to the lungs (less muscular)
4 chambers (R Atrium, L, R ventricle, L)
Vena Cava- brings in deoxygenated blood from the body
Blood passes from the heart to the lungs in the pulmonary artery
Oxygenated blood passed from lungs to heart in the pulmonary artery
Oxygenated blood pumped from the heart to the body in the aorta

Question 11

Negatives of the single circulation of blood?

Answer 11

Blood looses a lot of pressure as it passed through the gills before reaching the organs
This means blood travels to the organs slowly so it cannot deliver a lot of oxygen

Question 12

Job of Coronary arteries

Answer 12

Coronary arteries- to provide oxygen to the muscle cells of the heart
=> oxygen used in respiration to provide energy for the contraction

Question 13

Where is the Pacemaker

Answer 13

(right atrium)- resting heart rate is controlled by the pacemaker

Question 14

Features of a Arteries

Answer 14

Away from heart to organs (oxygenated blood)
Very high pressure blood
Very thick muscular walls- can withstand the high pressure
Elastic fibres stretch when blood passed, then recoils in between surges (keeps blood moving)

Question 15

Features of Capillaries

Answer 15

Substance exchange
=> glucose and oxygen to cells => Co2 back into blood
Very thin walls- diffusion pathway is short - diffuse rapidly

Question 16

Features of Veins

Answer 16

Thin wall- blood pressure is low so it doesn’t need to be thick
Valves- prevent backflow

Question 17

What is coronary heart disease

Answer 17

Coronary arteries- provide oxygen to muscle cells in heart
=> then used for respiration to provide every for contraction

In disease- layers of fatty material build up inside the arteries
=> they narrow reducing blood flow
=> lack of oxygen to heart
=> heart attack (starved of oxygen)

Question 18

Ways to fix this (2 methods) and adv and dis

Answer 18

Statins- drugs which reduce the levels of cholesterol in blood
=> slows rate that fatty materials build up in arteries

Advantages
Reduce risk of heart disease

Disadvantage
Unwanted liver problems

Treated with stents- tube inserted to artery to keep it open

Advantages
Can allow blood to flow normally through artery

Disadvantages
Will not prevent other regions of coronary artery from flowing
=> does not treat underlying causes of the disease

Question 19

Problem with Valves (adv and dis of animal and mechanical)

Answer 19

When valves do not fully open- heart has to pump extra hard to get the blood through
=> causes heart to enlarge
=> leaky valves- patient is weak and tired

Adv of Mechanical
Can last a lifetime

Dis of Mechanical
Increase risk of blood clots
Have to take anti- clotting drugs

Adv of Animal
Patient does not need to take drugs

Dis of Animal
Needs to be replaced every 12-15 years

Question 20

Artificial Heart Problems (dis of Artificial and donated)

Answer 20

Where heart cannot pump enough blood around body
=> heart failure
=> given donated heart

Disadvantage of Donated Heart
Not enough hearts to donate to everyone
Patient must take drugs to stop heart being rejected

Disadvantage of Artificial Heart
Increase risk of blood clotting
Not long-term solution

Question 21

Artificial Pacemakers and their benefits

Answer 21

If natural pacemaker stops it can beat too fast or too slow

=> too slow = not enough oxygen
=> too fast = blood not pumped properly

They send electrical signals to correct irregularities in the heart rhythm

Advantages
Very light- 20g-50g

Question 22

Features and Functions of:

Epidermal tissues
Palisade mesophyll
Spongy mesophyll
Xylem
Phloem
Meristem tissue

Answer 22

Covered with waxy cuticle
Help to reduce water loss by evaporation
=> waxy cuticle prevents water from moving out

Lots of chloroplasts
Photosynthesis can happen rapidly
Positioned at top of leaf to receive a lot of light

Lots of air spaces
Allows gases to diffuse in and out of cell

Made up of dead cells creating tube 
Strengthened by Lignin
Allows for movement of water and mineral ions
=> transpiration (single direction)
Lignin makes it strong 

Made of: Elongated cells with holes with small holes (pores) that join them together
=> end of walls are sieve plates
Cell sap can move from one phloem cell to the next through pores in the end walls.
Food (amino acids and sugar) can move up and down
Osmosis for water to go into roots
Then Transports food from sources to the sieve plates
=> active transport required
Translocation

Able to differentiate
Growth and repair

Question 23

What is translocation?

Answer 23

Translocation is the movement of food substances made in the leaves up or down the phloem, for immediate use or storage

Question 24

What is transpiration?

Answer 24

Transpiration is the loss of water vapour from leaves and stems of plant
=> it is consequence of gaseous exchange as stomata are open
=>ie for respiration , stored as starch

Question 25

Differences between Xylem and Phloem

Answer 25

Carries water and minerals vs carries food
Dead cells vs living
Cells are impermeable to water vs cells are permeable to food
Cells made of lignin vs made of cellulose

Question 26

Structure and adaptations of Hair Root Cells

Answer 26

Job- take up water by osmosis and mineral ions by active transport

Adaptations:
Large SA - increase rate of absorption
Lots of Mitochondria- release energy during respiration for active transport

Question 27

Structure and adaptations of Xylem

Answer 27

Lignin is used
=> support xylem structure and helps withstand the pressure of the water movement

Cells are hollow + join end to end to form a continuous tube
=> for water and mineral ions to travel through

Question 28

Structure and adaptation of Phloem

Answer 28

Sieve tubes- specialised for transport and have no nuclei
=> each tube has a perforated end so cytoplasm connects one cell to the next

Companion cells- transport in phloem require energy
=> companion cells attach themselves to sieve tubes, providing energy

Question 29

Factors that affect transpiration:

Answer 29

Temperature
evaporation is higher- inc rate of transpiration
Rate of photosynthesis inc
=> more stomata open for gaseous exchange- trans increases

Humidity/ dry weather
If humidity high- reduced concentration gradient of water inside and outside of leaf
=> slower rate of diffusion
=> decrease rate of trans

Windy Conditions
Good airflow removes water vapours from surrounding
=> creates conc gradient between leaf and air
=> increases water loss

Light intensity
More guard cells are responsive to light
=> when high they are turgid and stomata opens
=> water loss

Question 30

How do plants control water loss

Answer 30

When Light Intensity is high (day time)
=> stomata open
This means Co2 can diffuse into leaf- used in Photo.

Temperature high- Stomata closes to reduce water loss by transpiration
=> plant cannot photo.

Thin structure– Short distance for carbon dioxide to diffuse into leaf cells. The stomata that allow carbon dioxide to diffuse into the leaf and oxygen to diffuse out.

Wilting- protection mechanism against further water loss
=> reduces surface area available for water loss