Unit B 死记烂背 Flashcards
1
Q
B1,1
3 Properties of carbon allowing chemical diversity
A
- Carbon forms covalent bonds
- Carbon forms up to 4 single bonds, or combination of bonds
- Forms straight/branched chains or single/multiple rings
2
Q
B1.1
4 Properties of monosaccharides
A
- Solubility
- Transportability
- Chemical stability
- Oxidation yields energy
3
Q
B1.1
4 Properties of glucose
A
- Solubility – dissolves in water as it is polar
- Transportability – dissolves in blood plasma
- Chemical stability – cyclic molecule with -OH in axial region
- Oxidation yields energy – respiration releases energy
4
Q
B1.1
4 Forms of storage of glucose
A
- Amylose (eg. potatoes) – linear starch chain linked by a-1,4-glycosidic bonds
- Amylopectin (main component) (eg. corn) – starch chain linked by a-1,4-glycosidic bonds, with branches joined by a-1,6-glycosidic bonds every 24-30 units
- Cellulose – linear chain linked by b-1,4-glycosidic bonds, cross-linked by H-bonds and bundled into microfibrils
- Glycogen – chain linked by a-1,4-glycosidic bonds, with branches joined by a-1,6-glycosidic bonds every 8-12 units
5
Q
B1.1
4 Functions of glycoproteins
A
- Cell-cell recognition
- Receptors
- Ligands
- Structural support
eg. ABO blood antigens
6
Q
B1.1
3 differences in properties of saturated/unsaturated lipids
A
- Solid/liquid at RTP
- High/low viscosity
- High/low melting point
7
Q
B1.1
Storage of fats in plants and endotherms
A
- Plants – unsaturated fats and oils in seeds for germination
- Endotherms – liquid droplets in adipocytes for respiration
8
Q
B1.2
7 Functions of proteins with examples
A
- structure (macro/micro) –- collagen/histone
- transport (extra/inter/intracellular) –- haemoglobin/ channel protein
- enzyme –- lysozyme
- movement –- actin / tubulin
- hormones –- insulin
- antibodies –- immunoglobulin
- storage –- albumin
9
Q
B1.2
4 examples of types of R-group
A
- Acidic – aspartic acid
- Basic – lysine
- Polar – serine
- Non-polar – alanine
10
Q
B1.2
Origins of H-bonds, S-bonds and ionic bodns in proteins
A
- H-bonds – between polar hydrophilic R-groups
- S-bonds – between cysteine residues
- ionic bonds – between NH2 or C=O charged by binding/dissociation of H+, and charged R-groups
11
Q
B1.2
Levels of Polypeptide Structure
A
Primary Structure - sequence of amino acids, linked by peptide bonds
Secondary Structure – local folding of peptides into a-helices or b-pleated sheets
Tertiary Structure - folding of polypeptide via H-/S-/ionic bonds
Quaternary Structure - arrangement and interaction of two or more polypeptide chains to form a functional protein
12
Q
B1.2
Conjugation in Haemoglobin, Insulin and Collagen
A
- Haemoglobin – tetramer with haem groups and iron
- Insulin – non-conjugated dimer
- Collagen – non-conjugated trimer
13
Q
B1.2
4 Properties of Globular Proteins
A
- Tertiary structure, often spherical in shape
- Water-soluble
- High pH/temperature sensitivity
- Function as enzymes, transporters, regulators
eg. Insulin has a hydrophilic exterior to be transported in blood plasma, but a hydrophobic core to be chemically stable
14
Q
B1.2
4 Properties of Fibrous Proteins
A
- Secondary structure, often linear or long in shape
- Water-insoluble
- Low pH/temperature senstivity
- Function as structural support and stabilisation
eg. Collagen is made of 3 twisted H-bonded polypeptides containing glycine, proline, and hydroxyproline
15
Q
B2.1
7 Point Explanation of Cholesterol Effect on Membrane Fluidity
A
- Polar group faces aqueous external environment
- Non-polar regions face interior of bilayer
- Rigid steroid structure strongly interacts with phospholipids
- Increases fluidity at low temperature by interfering with packing of fatty acid chain
- Decreases fluidity at high temperature by reducing mobility of phospholipis
- Broadens phase transition of freezing
- Prevents abrupt membrane fluidity changes
16
Q
B2.1
7 Point Explanation of Effect of Temperature on Fatty Acid Saturation
A
- Unsaturated tails are kinked so are less dense and have lower melting point
- At low temperature, less saturation to prevent membrane solidification
- Membrane fluidity needed for protein function
- Saturated tails are straight, so can be more tightly packed leading to higher melting point
- At high temperature, more saturation to strengthen membrane
- To maintain appropriate membrane fluidity
- Eg. cold-blooded organisms and hibernating animals
17
Q
B2.1
Example of ligand-gated channel in a neuron (3)
A
Nicotinic acetylcholine receptors
- Postsynaptic receptors have acetylcholine/nicotine binding site
- Binding causes a reversible conformational change allowing inward facilitated diffusion of 5 sodium ions
- Influx of sodium depolarises membrane, helping to generate the action potential
18
Q
B2.1
Example of voltage-gated channel in a neuron (3)
A
Sodium/Potassium channels
- Ball-and-chain mechanism controls opening of the membrane
- Voltage change causes a conformational change in the pore, causing the ball to detach allowing sodium influx/potassium efflux
- Influx of sodium depolarises membrane, potassium efflux repolarises membrane
19
Q
B2.1
Example of direct active transport (5)
A
Sodium-Potassium Pump
- Pump is open to inside of cell. Sodium ions bind to 3 binding sites
- Binding triggers ATP hydrolysis. Pi binds to pump, causing a conformational change.
- Pump is open to outside of cell. Potassium ions bind to 2 binding sites.
- Bindings triggers release of Pi from pump, causing a conformational change.
- Bidirectional active transport builds a high Na+ concentration outside and high K+ concentration inside the cell to reestablish membrane potential after hyperpolarisation.
20
Q
B2.1
4 Point Explanation of Role of Phospholipids in Plasma Membrane
A
- hydrophilic phosphate faces aqueous external environment
- hydrophobic fatty acids face each other forming core
- low permeability to large or charged species
- effective patrtial permeability
21
Q
B2.1
5 Functions of Proteins in Membranes
A
- Facilitated diffusion and Active transport
- Cell recognition
- Cell adhesion
- Chemical reception
- Enzymes
22
Q
B2.1
3 Functions of glycocalyx
A
- Cell recognition
- Cell adhesion
- Cell signalling
23
Q
B2.1
Role of aquaporins in transport of water (3)
A
- Aquaporins are tetramers of water channels with hydrophilic R-groups
- Hydrophilic R-groups attract polar H2O by hydrogen bonds
- H2O molecules bidrectionally pass through each channel in single file
24
Q
B2.1
5 Point Explanation of Function of Endocytosis and Exocytosis
A
- Endocytosis - formation of vesicles by inward pinching of membrane
- Exocytosis - fusion of vesicles with membrane
- Possible due to strength and fluidity of fluid mosaic membrane
- Energy needed in form of ATP to transport vesicles
- Eg. phagocytosis; and synaptic transmission
25
# B2.2
Advantage of separating nuclei and cytoplasm
- Separation of transcription and translation allows post-transcriptional modification, leading to more chemical diversity
26
# B2.2
3 Adaptations of mitochondria
- Double membrane with small intermembrane space
- Large surface area of cristae
- Compartmentalisation of enzymes and substrates of Krebs cycle in matrix
27
# B2.2
3 Adaptations of chloroplasts
- Small volume of fluid inside thylakoids
- Large surface area of thylakoid membrane
- Compartmentalisation of enzymes and substrates of Calvin cycle in stroma
28
# B2.2
4 Point Explanation of Significance of Compartmentalisation
* Organelles have specific function
* Compartmentalisation separates incompatible reactions
* Compartmentalisation allows correct concentration of metabolites
* eg. hydrolytic enzymes in lysosomes and phagocytic vacuoles are acidic. Compartmentalisation separates the enzymes from neutral cytoplasm to prevent them from denaturing/ hydrolysing essential cellular components
29
# B2.2
3 Functions of Nuclear Membrane
* Protect DNA from reactions in cytoplasm
* Inner membrane controls transport of transcription factors through nuclear pores
* Separates transcription and translation, post-transcriptional modification creates protein variants
30
# B2.2
2 Point Explanation of Function of Nuclear Pore
1. Protein-lined channel in nuclear envelope
2. Regulate transport of folded proteins, transcription factors and ribosomal components
31
# B2.2 [Kognity]
3 components of Golgi apparatus
- cis: receive proteins from rER
- medial: modify proteins
- trans: package proteins into vesicles for transport
32
# B2.2 [exam question]
6 Adaptations of Organelles
* Nuclear pore allows mRNA to travel for translation
* Free ribosomes synthesise proteins for intracellular use
* rER ribosomes synthesise proteins for extracellular use
* Folded mitochondrial cristae surface area for oxidative phosphorylation
* Folded chloroplast membrane increases surface area for light-dependent reaction
* Range of pigments absorbs light for photosynthesis
33
# B2.2 [exam question]
3 Point Explanation for Polysome Function
1. Polysomes are ribosomes translating same mRNA
2. Polysomes simultaneously produce multiples copies of same protein
3. Cell needs multiple copies of particular protein
34
# B2.2
Role of clathrin in vesicle formation (3)
1. As the membrane invaginates, clathrin polymerises into a clathrin-coated pit
2. Brings together cytoskeleton for budding and scission of vesicles/endosomes
3. Clathrin coat is hydrolysed and reused
35
# B2.3 [exam question]
4 Point Explanation for Effect of Size on Heat Loss
* large organisms have low SA:V ratio
* limited heat loss by radiation
* small organisms have high SA:V ration
* significant heat loss by radiation
36
# B2.3
5 Properties of Stem Cells
* Undifferentiated
* Capable of self-renewal
* Found in all multicellular organisms
* Only few adult cells retain stem cell properties
* Potency: Unipotent, multipotent, pluripotent, totipotent
37
# B2.3
5 Point Explanation of Morphogen Function
* Variation in cell-signalling morphogen concentration in cells of an early embryo
* Morphogens diffuse out from the morphogen-producing cell, producing a gradient
* Developing cells regulate gene expression based on their distance from the cell
* Gene expression determines the direction and extent of growth of tissue
* Eg. length of digits, location of nose
38
# B2.2
2 Examples of stem cell niches in adults
- Bone marrow: stem cells differentiate by haematopoeisis, and are maintained by supportive cells
- Hair follicles: bulge stem cells proliferate into new hair cells
| Bulge stem cells are the name for stem cells in hair follicles
39
# B2.2
4 Adaptions to raise SA:V ratio with examples
- Small size -- prokaryotes
- Flattening -- simple squamous epithelium of PCT and alveolar membranes
- Microvilli -- enterocytes have about 600 microvilli
- Invaginations -- mitochondrial cristae, microvilli
40
# B2.3
Adaptation of Type I Pneumocytes
* **Squamous** -- reduced diffusion distance
* Tight junctions -- prevent tissue fluid leaking into alveolar air space
| You only need the bolded one, but for me it makes sense to mention both.
41
# B2.3
Adaptation of Type II Pneumocytes
- Cuboidal -- contain many organelles
- **Lamellar bodies** -- secrete surfactant, which reduces surface tension to prevent alveoli from collapsing
| You only need the bolded one, but for me it makes sense to mention both.
42
# B2.3
4 Adaptations of Cardiac Muscle
* Contractile myofibrils/sarcomeres -- allows contraction
* Branching (by gap junctions at intercalated discs) -- synchronisation of cardiomyocytes as the electrical impulse passes through efficiently
* Single nucleus -- synchronisation of cardiomyoctes
* Many mitochondria -- respiration for energy
43
# B2.3
4 Adaptations of Skeletal Muscle
- Many contractile myofibrils/sarcomeres -- allow large extent of voluntary movement
- Unbranched -- enables precise control of voluntary movement
- Multinucleated syncitia -- more protein synthesis and repair
- Many mitochondria - respiration for energy
44
# B2.3
3 Adaptaions of Ova
* Large cytoplasm - nutrition for zygote development
* Cortical granules - prevent polyspermy via cortical reaction
* Moved by cilia in fallopian tube instead of independently - conserve energy
45
# B2.3
3 Adaptations of Sperm
* Middle piece with mitochondria - energy to travel
* Acrosome - digestive enzymes facilitate acrosomal reaction
* Streamlined + flagellum - swim through fluid
46
# B3.1
5 Properties of Gas Exchange Surfaces
- high surface area
- permeability
- thin tissue layer
- moist surfaces dissolve gas
- maintains steep concentration gradient.
47
# B3.1
3 Adaptations of Alveoli
Alveolar fluid - moistens alveolar walls for gas diffusion
Surfactant - prevent collapse of alveolar walls during exhalation
Many small alveoli next to capillaries - short diffusion distance
48
# B3.1
6 Step Process of Inspiration
1. Diaphragm contracts
2. External intercostal muscles contract, internal muscles relax
3. Ribcage moves up and out
4. Increased thoracic volume
5. Decreased thoracic pressure
6. Air moves into the lungs
49
# B3.1
6 Step Process of Expiration
1. Diaphragm relaxes
2. External intercostal muscles relax, internal muscles contract
3. Ribcage moves down and in
4. Decreased thoracic volume
5. Increased thoracic pressure
6. Air moves out of the lungs
50
# B3.1
3 Plant Adaptations for Gas Exchange
- Thin and flat leaves - large surface area for gas diffusion and for light
- Hydrophobic waxy cuticle - reduces water loss
- Air pockets in spongy mesophyll- maintain concentration gradient for CO2 and O2
51
# B3.1
5 Regions of Spirometry Graph
- Inspiratory Reserve Volume = maximum additional volume of air that can be inhaled
- Tidal Volume = fluctuation in volume of normal breathing
- Expiratory Reserve Volume = maximum additional volume of air that can be exhaled
- Forced Vital Capacity = total air that can be exhaled
- Residual Volume = volume of air in lung which cannot be exhaled
52
# B3.1
3 Point Explanation for Foetal Oxygen Supply
* HbF has gamma peptides, HbA has beta peptides
* HbF has higher oxygen affinity than HbA (comparative Bohr shift)
* Foetus obtains oxygen through placenta
53
# B3.1
4 Point Explanation for Haemoglobin Oxygen Carrying Capacity
* At low partial pressure, there are few successful collision of O2 with haem binding sties
* When one oxygen binds, conformational changes assist binding of second and third oxygen
* At high partial pressure, haemoglobin is highly saturated, there are few successful collisions
* Haemoglobin loads oxygen from cells with high partial pressures and unloads into cells with low partial pressure
54
# B3.2
5 Step Process of Interstital Fluid Formation
1. On the arteriole end, hydrostatic pressure is greater than osmotic pressure.
2. Water and glucose move out by ultrafiltration into the space between cells, forming interstitial fluid and moves into cells.
3. Metabolic waste products, CO2 and urea, move out of cells through the interstitial fluid.
4. On the venous end, osmotic pressure is greater than hydrostatic pressure due to the high solute concentration in the plasma.
5. Tissue fluid is returned to the circulation of lymphatic system.
55
# B3.2
4 Step Process of Heart Systole
1. SA nodes initiate contraction.
2. Atrial systole.
3. Electrical impulses travel through Bundle of His and to Purkinje fibres.
4. Ventricular systole.
56
# B3.2
3 Point Explanation of Evapotranspiration
1. Evaporation of water vapour from stomata in leaves generates a negative pressure, drawing water upwards.
2. Due to the hydrogen bonding between polar H2O molecules, water moves up in a continuous column.
3. Adhesion of water to the xylem lignin walls also maintains the continuous stream. Adhesion additionally narrows the xylem diameter to assist with maintaining water transport.
57
# B3.2
4 Step Process of Root Pressure Generation
1. Abiotic factors do not favour evapotranspiration
2. Active transport of mineral ions into root hair cells
3. Increases solute concentration reduces water potential, causing water to move in by osmosis.
4. Movement of water into the xylem generates positive hydrostatic pressure potential.
58
# B3.2
3 Adaptation of Xylems
* Lignin - strength and waterproofness
* Pit cells - movement of water between adjacent cells in xylem
* Lumen has no cytoplasm - maximise water transport capacity
59
# B3.2
8 Step Process of Translocation
1. Bidirectional movement from source to sink
2. Sucrose is produced in leaves by photosynthesis
3. Sucrose is actively transported by the apoplast route
4. Surcrose is loaded into companion cells
5. High concentrations of solutes at the source cause uptake of water by osmosis
6 Water provides hydrostatic pressure for mass flow
7. Sucrose is unloaded / stored / used at sink
8. lowers pressure at sink / creates pressure differential / water re-entry to xylem
60
# B3.2
4 Adaptations of Phloem
- Perforation in sieve plates - sap flows freely
- Anucleate sieve tube elements - maximise phloem sap capacity
- Mitochondria in companion cells - active transport out of sources and into sinks
- Plasmodesmata - allows transport between siee tube elments and companion cells
61
# B3.3
5 Regions of Sarcomeres
M line - organises myosin
Z disc - organises actin
H zone - myosin only
I band - actin only
A band - myosin and actin present
62
# B3.3
10 Step Process of Sliding Filament Model
1. Action potential travels across rough sacroplasmic reticulum
2. Voltage gated Ca channels open, Ca efflux
3. Ca binding to troponin causes conformational change
4. Leaving of troponin removes tropomyosin
5. ATP hydrolysis causes myosin head to change angle, storing chemical energy as potential energy
6. Myosin forms cross-bridge with actin
7. ATP and Pi release causes power stroke towards M-line
8. Sarcomere contracts (8-10 nm)
9. ATP attaches to myosin, cross-bridge breaks
10. Repeated ATP hydrolysis supplies energy for repeated sarcomere contraction
63
# B3,3
4 Functions of Titin
- helps the sarcomere return to its original length
- adds to force of contraction
- prevents overstretching, provides passive resistance to maintain structural integrity and health of muscle
- holds each myosin filament in the correct position between 6 actin filaments
64
# B3.3
5 Components of Synovial Joints
* Synovial Fluid - reduces friction, nourishes articular hyaline cartilage
* Joint Capsule - seals synovial fluid, prevents disolocation
* Articular Cartilage - reduce friction, absorb shock
* Ligaments - prevents dislocation
* Tendons - medium between muscle and bone
65
# B3.3
4 Reasons for Locomotion
* Foraging
* Escaping danger
* Mate selection
* Migration
66
# B3.3
10 Adaptation of Dolphins
* Streamlined body shape, flippers, flukes, dorsal fin, smooth skin, even distribution of blubber - reduce drag
* Blubber around organs, low SA:V ratio - reduce heat loss
* Flippers - steering
* Fluke - propel dolphin
* Dorsal fin - prevents rolling over
* Low density blubber - buoyancy
* Blowhole - periodic breathing
* Separated mouth and lungs - prevent water entering lungs
* Large lungs, high alveoli capillary exposure, high myoglobin, high blood volume, high erythrocyte count, high haemoglobin concentration - oxygen storage and gas exchange
* Blowhole - whistles and clicks as communication
67
# B4.1
6 Adaptations of Marram Grass
* Rolled leaves with hairs
* Stomata are located on the inside of the leaf
* Stomata are surrounded by hairs
* The inner epidermis is highly folded
* Deep root system
* Rhizomes
68
# B4.1
3 Adaptations of Mangrove Plants
* Pneumatophores (aerial roots)
* Stilt roots
* Propagation
69
# B4.1
Adaptations of 5 Plants to Abiotic Conditions
* Ferns grow large, thin leaves with high chlorophyll content.
* Cacti have a thick waxy epidermis to reflect sunlight and reduce transpiration.
* Tomatoes have heat shock proteins to protect against high temperatures.
* Rice plants can close the stomata during droughts to reduce water loss.
* Legumes have symbiotic relationships nitrogen-fixing bacteria.
70
# B4.1
Adaptations of 5 Animals to Abiotic Conditions
* Polar bears and penguins have thick fur for insulation.
* Camels and kangaroo rats store water in the body.
* Nocturnal animals (eg. bats, owls) avoid diurnal predators.
* Herbivores have specialized teeth to digest plant tissue.
* Bats and ground squirrels hibernate to conserve energy.
71
# B4.1
3 Limiting Factors of Coral Reef Growth
Temperature 23 - 29 C
pH 8.0 - 8.4
Water clarity
72
# B4.1
3 Adaptations of Camels
- Thick skin and osmotic cells
- Fluctuating internal body temperature
- Fat-storing humps
73
# B4.1
5 Adaptations of Cacti
- Thick waxy cuticle and epidermis
- Spikes
- Deep stoma, only opens at night
- Large stems
- Shallow roots
74
# B4.1
4 Adaptations of Scorpions
- Slow metabolism
- Water-absorbing exoskeleton
- Venom and hard exoskeleton
- Excretion system produces semi-solid guanine
75
# B4.1
3 Adaptations of Kangaroo Rats
- Seed diet
- Large hind legs
- Nasal passage specializes in water reabsorption
76
# B4.1
3 Adaptations of Pitcher Plants
- Bright colours and scents
- Waxy internal rim
- Large superior lip
77
# B4.1
2 Adaptations of Flying Lizards
- Streamlined limbs
- Patagium (elongation of thoracic limbs)
78
# B4.1
3 Adaptations of Gibbons
- Hook-shaped hands, long arms
- Long legs
- Wide shoulder joints
79
# B4.1
Adaptation of Orchid Mantis
- Camouflage against orchids
80
# B4.2
6 Adaptations of Plants
* Phytochemicals
* Thick, rigid leaves with thorns and trichomes.
* Aerial roots
* Epiphyte behaviour (eg. orchids, strangler figs)
* Large leaf surface area (shrub layer)
* Camouflage
81
# B4.2
2 Adaptations of Herbivores
* Strong mandibles, large teeth with thick enamel layer and tooth growth. Diastema.
* Insect stylets (proboscis in aphids)
82
# B4.2
4 Adaptations of Prey
* Large field of view, small area of binocular vision, large ears
* Camouflage
* Defence mechanisms
* Collaborative grouping behaviour
83
# B4.2
4 Adaptations of Predators
* Sharp teeth (esp. canines) and claws.
* Aggressive mimicry
* Sensitive hearing and olfactory organs, night vision
* Toxins or venoms.
84
# B4.2
4 Properties of Herbivore Teeth
Incisor - Long, flat
Diastema
Pre-molar - Large, flat
Molar - Large, flat
85
# B4.2
4 Properties of Omnivore Teeth
Incisor - Sharp
Canine - Pointed
Pre-molar - Large, flat
Molar - Large, flat
86
# B4.2
4 Properties of Carnivore Teeth
Incisor - Sharp
Canine - Long, sharp
Pre-molar - Sharp
Molar - Large, flat
