past papers 1 Flashcards
(31 cards)
explain what occurs in the nucleus of a cell
synthesis of RNA
describe a feature of peritoneal dialysis
urea and mineral ions pass into the tissue fluid
the hormone hcg can be detected in urine
what property allows it to be detected
HCG has a molecular mass of less than 69,000
why is it more difficult for insects than mammals to control temp
-mammals and bird have thicker layer of insulation
-insects have a larger SA:VOL
-insects have greater rate of heat loss
outline the reasons why insects and other animals need well developed transport systems
-have high metabolic rate/ demand
-small SA:VOL
-diffusion distance to great / diffusion inefficient
-need large O2 supply
-to maintain concentration gradients
what must you follow to draw a scientific drawing/ diagram
-no shading
-use a sharp pencil
-use ruled label lines
-include a scale bar
-large size - use at least 50% space provided
-tittle
-state magnification
-use plain paper
what is meant by a limiting factor
-a factor that will determine the rate when at lower levels
explain why a plant leaf is described as an organ
-an organ is a collection of tissues that are adapted to a specific function
-leaves have epidermis and spongey mesophyll to carry out photosynthesis
compare the processes occurring in the proximal and distal convoluted tubules
similarities
-both use active transport
-both involve co-transport
-both involve selective reabsorption
-both involve use of sodium ions
differences
-DCT involves use of calcium ions
-DCT involves ions only
-PCT involves ions and other molecules
what is a symptom you would expect if ADH was prevented from binding
aqua porins don’t open as receptors don’t respond to ADH
-less water is reabsorbed
-always thirsty
explain why podocytes are usually unable to undergo mitosis
-are differentiated
-shape is to irregular
-in G0 phase
-cytoskeleton cannot function
-spindle fibres cannot form
what features of adult stem cells make them suitable for regeneration of tissues in the kidney
-are multipotent
-differentiate to become any cell type within kidney
-water can fill air spaces around seedlings
-this prevents oxygen from reaching root hair cell
-using your knowledge of aerobic and anaerobic respiration explain why overwatering can kill plants
- no aerobic respiration takes place
-no link reaction, kreb cycle, ETC
anaerobic respiration
-only glycolysis occurs
-alcohol fermentation occurs
-pyruvate- ethanal- ethanol
effect on plant
-ethanol is toxic
-alcohol fermentation is irreversible
-no active transport
-plant cant create water gradient - water cant remain turgid
-less/ no photosynthesis
explain why glucose is needed for the contraction of skeletal muscle
-glucose as raspatory substrate
-glucose to produce ATP
-ATP needed in muscles for breaking cross-bridges between myosin and actin
-ATP hydrolysed to ADP and PI to reset myosin head
-ATP for active transport of calcium ions back into sarcoplasmic reticulum
plan an investigation into the rate of transpiration in two species of plant that would allow valid data collection
method and planning
–movement of bubble in potometer/ mass measured
-timing distance travelled by bubble
-repeating investigation with two different plant species
-repetition to gain replicas
-statistical test- mean/ rate
name variables controlled
-temperature
-humidity
-light
-wind movement
-surface area of leaves
give features of cellulose that make it suitable as the basis of plant cell walls
-insoluble
-unreactive
-high tensile strength
-flexible
-can form h bonds with neighbouring chains
outline the processes involved in the generation of ATP through chemiosmosis
-occurs in the mitochondria on the membrane
-involves inner membrane and matrix
-involves movement of hydrogen across membrane
-use of ATP synthase
-h+ ions pumped out of matrix across membrane into intermembrane space
-proton gradient created
-ATP synthesis produces ATP from ADP and PI
-H+ ions move from high conc to low conc
outline the importance of photosynthetic pigments in photosynthesis
-pigments absorb light photons
-electrons excited by higher light level
-accessory pigments pass energy to primary pigments
-primary pigments pass electrons to ETC
-for light dependent reaction / photophosphorylation
explain how paralysis of the diaphragm can lead to suffocation
no/ little change in volume of thorax
no / little change in pressure in the thorax
-no/ little air drawn into the lungs
compare and contrast the circulatory systems of mammals and fish
similarities
-both are closed systems
-both have a heart
-both carry oxygen using haemoglobin
-both have arteries/ veins/ capillaries
differences
-fish have single circulation, mammals have double
-fish have 2 chambers and no septum in heart, humans have 4 chambers and a septum
-fish blood pressure is lower, mammals pressure is higher
-fish is less efficient, mammals is more efficient
-fulfils fish needs as lower oxygen demand, fulfils needs of mammal as have higher oxygen demands
high partial pressure of co2 reduce the affinity for oxygen of haemocyanin
suggest how co2 could reduce the affinity for oxygen of haemocyanin
-co2 forms carbonic acid
-carbonic acid dissociates into H+
-H+ causes change in tertiary structure of haemocyanin
explain why anabolic steroids are effective when applied to the surface of the skin
-muscles sit close to skin surface so short diffusion distance
-can diffuse through the skin and into blood vessels
-steroids are lipid soluble
-skin has large surface area for absorption
explain what is meant by conjugated protein
-a 4D/3D structure that involves prosthetic groups
-contains non-protein groups
properties of water that are essential for sustaining life on earth
-water less dense when freezes so whole bodies of water dont freeze as ice insulates water below - means nutrient ccle continues + fish can swim
-ice is habitat for polar bears
-h-bonds between molecules causes adhesion and cohesion allowing nutrients to be transported around a plant
-high surface tension provides habitat
medium for chemical reactions
-allows buoyancy / support for aquatic organisms
-allows for hydrostatic skeleton
