Biology Component 2 June 2016 AS Paper Flashcards
Describe one adaptation of red blood cells for transport of Oxygen [1]
Biconcave/No nucleus/ Thin/ Flexible/ Contains haemoglobin
Explain how training at altitude can help improve an athlete’s performance when subsequently competing at sea level [1]
At sea level, more red blood cells meaning more oxygen can be delivered to the muscles
The physiology of delivering oxygen to muscles during exercise is linked to the
removal of carbon dioxide which is mainly transported in the form of hydrogen
carbonate ions. Explain how carbon dioxide in the plasma becomes hydrogen
carbonate ions inside red blood cells [3]
CO2 moves in RBC because there is more CO2 ouside than inside by diffusion.[1]
CO2 reacts with water to form carbonic acid H2CO3 [1]
Due to the presence of carbonic anhydrase in RBC, carbonic acid dissociates into H+ ions and HCO3- ions[1]
Describe how the production of hydrogen carbonate ions account for the Bohr effect [2]
H+ displaces oxygen from haemoglobin=2 marks
Cytochrome oxidase is an enzyme found in mitochondria. It has a quaternary structure.
The gene for one polypeptide chain in cytochrome oxidase has 1542 nucleotides. State
how many amino acids make up that chain in one molecule of cytochrome oxidase,
explaining how you reached your answer.[2]
154/(152 if justified with start and stop codons) [1]
3 neuclotides/bases code for one amino acid because of triplet code
Radioactivity and fluorescence were both detected in the sap from each individual aphid.
Explain why this observation does not support the mass flow hypothesis and name an
alternative hypothesis which could account for the observation.[3]
because mass flow is from sources to sinks/ One direction [1]
This flow is bidirectional/two ways [1]
Cytoplasmic Streaming[1]
Describe a method the group could use to randomise the positions of the quadrats.
[2]
Mark out a grid in the wood[1]
Use random number generator to pick coordinates [1]
Different plants are affected differently by coppicing.
Describe the effect coppicing has had on Dog’s Mercury and suggest an explanation for how coppicing might have caused this effect. [3]
Dog’s Mercury has been eliminated/killed off [1]
Coppicing has allowed more light/water through/coppicing results in less shade [1]
Dogs’ Mercury cannot surive in high light intensity [1]
A double circulatory system is found in mammals whereas a single system is found in fish.
Describe the difference between the systems and explain why a double system is more efficient. [2]
In single systems, there is one curcuit, in double systems there are 2 separate circuits [1]
It allows oxygenated blood to be delivered to organs under high pressure[1]
Suggest the consequences of the defects on the circulation of blood and explain the reasons why the oximeter readings would be different from a person without such defects [3]
Defects= hole in the septum
faulty valve
connection in aorta
Oximeter will detect less oxygenated blood [1]
Any two from :
• (The hole in the septum will allow) deoxygenated blood
(from right ventricle) to mix with oxygenated blood in (left ventricle)/ aorta) (1) Must not be in incorrect context
• The connection will allow deoxygenated blood into aorta/allows deoxygenated and oxygenated blood to mix (1)
• Faulty valve will allow backflow of blood into the left ventricle (1)
Rabbit cells can produce α amylase to digest starch, but cannot produce an enzyme to digest cellulose.
With reference to the structure of starch and cellulose molecules, explain why α amylase is unable to digest cellulose even though starch and cellulose are both
polymers of glucose. [3]
Any three (x1) from:
1. Reference to active site of α amylase/ lock and key
hypothesis/ ref to enzyme substrate complexes (1)
2. complementary shape only to starch (not cellulose)(1)
3. Starch contains α glucose but cellulose contains β glucose/reference to α bonds and β bonds (1)
4. Reference to {coiling in starch /straight chains in cellulose/ microfibrils in cellulose/ cross linking in cellulose / alternate
(glucose) molecules rotated by 180 in cellulose/ molecules
not rotated in starch (1)
Explain how rabbits are able to digest cellulose without their cells being able to
produce the necessary enzyme.[1]
Bacteria produce the enzyme cellulase [1]
With reference to the relative positions of the main organs of the digestive system, explain the reasons for the nutritional difference between the two types of faeces. [4]
- The small intestine comes before the caeum in the digestive system [1]
- Cellulose digestion takes place after absorption so sugar is not absorbed
- Rabbits eat the soft faeces allowing faeces to pass through alimentary canal twice
- After eating, the sugar/nutrients can then be absorbed
Describe how the gills of both bony fish and axolotls are adapted to increase the efficiency of
gas exchange
• large surface area due to presence of gill filaments/
plates/ lamellae
• permeable
• rich blood supply to maintain concentration gradient
between water and blood
• reduced diffusion distance
• ventilation mechanism
explain how structures in the heads of bony fish enable them to be highly
active even when oxygen levels are relatively low but axolotls are slower moving under these
conditions.
II • separate buccal and opercular/gill cavities
• operculum/bony plates can close gill cavity
• lowering floor of buccal cavity increases volume and
decreases pressure in buccal cavity
• mouth opens and water enters
• mouth closes floor of buccal cavity is raised
• increased pressure forces water over the gills
• water and blood flow in opposite direction –
countercurrent flow
• maintain a concentration gradient for O2 across
whole of gill surface
• O2 absorption is more efficient/ blood and water do
not reach equilibrium/more O2 is absorbed
III • Axolotls have external gills so no ventilation
mechanism/rely on water currents/whole body
movements to ventilate gills
• Reference to parallel flow
• Cannot absorb as much / less efficient at O2
absorption which is needed for aerobic respiration
